MANUFACTURING HEAT TREAT TECH Archives

Decarburized Layer in Steel: Understanding, Evaluation, and Control

Hardness results that fall below specification are not always caused by heat treatment errors. In this Technical Tuesday installment, Ana Laura Hernández, founder of Consultoría Carnegie, examines how decarburization develops, how it affects hardness and surface properties, and the practical methods heat treaters can use to evaluate, control, and prevent it through metallurgical analysis and process discipline.

This informative piece was first released in Heat Treat Today’s July 2026 Annual Super Brands Issue print edition.

If you have any comments or queries, on this article, let us know at editor@heattreattoday.com.

Para leer el artículo en español, haga clic aquí.

Introduction: When Results Do Not Match Theory

In heat treatment operations, hardness results outside of specification are often attributed to deviations in process parameters, operational errors, or variations in the chemical composition of the material. However, there are cases where the root cause is related to metallurgical phenomena that directly affect the surface of the material.

A representative case involved a batch of ten forged components weighing more than 5 tons each, manufactured from AISI 4340 steel. The applied heat treatment process was known and previously validated: normalizing, quenching, followed by tempering in a range of 600–610°C (1112–1130°F), with the objective of meeting the required mechanical properties. After completing the heat treatment, the inspection team reported hardness values approximately 20–30 HB below specification. This result was unexpected, considering that AISI 4340 steel, due to its alloying elements, maintains relatively high hardness values even at relatively high tempering temperatures. A hardness reevaluation was requested, increasing the surface preparation depth up to 5 mm. However, the hardness values only increased slightly (~5 HB), without reaching the required levels.

Under pressure due to delivery timelines, it was decided to reprocess the components. The complete heat treatment cycle was applied again, adjusting the tempering temperature to 580°C (1076°F), which, from a metallurgical standpoint, should increase hardness. Nevertheless, the results remained practically unchanged. The chemical composition was verified using PMI, confirming that the material was indeed AISI 4340 steel. Additionally, the evaluation piece “Qualification Test Coupon” (QTC) indicated high hardness values, consistent with the expected behavior of the material.

Given the inconsistency between experimental results, metallurgical fundamentals, and prior experience, a deeper analysis of the process history was conducted, correlating variables from each stage of processing. This is where the key to a proper failure analysis lies: thoroughly understanding the history of the component.

It was identified that, prior to heat treatment, the components had remained inside a furnace within a temperature range of 800–900°C (1472–1652°F) for approximately three days, due to delays in the rolling process caused by maintenance issues. As a result of prolonged exposure and poor communication between shift operators, the components remained inside the furnace at “lower temperatures” while waiting to complete the final rolling step. Although not at rolling temperatures, this prolonged exposure in a non-controlled atmosphere promoted decarburization of the material.

To validate this hypothesis, a longitudinal cut was performed on one of the components, and hardness measurements were carried out in the core. The results confirmed that the material exhibited significantly higher values in the interior, revealing a decarburized surface layer. This case demonstrates the importance of: Analyzing the full material and process history before concluding a non-conformance.

What Is Decarburization?

Figure 1. Representative schematic of the decarburization and oxidation process. | Image credit: Consultoría Carnegie

Steel is a solid solution based on iron and carbon, where mechanical properties depend directly on the carbon content and the alloying elements present. Decarburization is a metallurgical phenomenon consisting of the loss of carbon from the surface of steel when it is exposed to high temperatures in atmospheres with oxidizing potential or low carbon potential (Figure 1). This phenomenon commonly occurs during forging, hot rolling, normalizing, annealing, and heat treatment in conventional furnaces without atmosphere control.

From a thermodynamic perspective, decarburization occurs when the chemical potential of carbon in the steel is higher than that of the surrounding environment, which drives carbon diffusion toward the surface. In the presence of oxidizing gases, carbon reacts to form gaseous species:

It can also react with water vapor or carbon dioxide, accelerating the process. As a result, a carbon gradient is generated (surface vs. core), the microstructure is altered, and mechanical properties are degraded, especially at the surface.

Oxidation and Its Relationship with Decarburization

Decarburization is closely related to oxidation processes. Oxidation occurs when oxygen reacts with the metal, forming oxides on the surface. This process depends on the thermodynamic equilibrium between the partial pressures of the gases present, which can be analyzed using diagrams such as the Ellingham-Richardson.

An increase in temperature accelerates both oxidation and decarburization, which is why the use of controlled atmosphere furnaces is essential to prevent these phenomena.

Process Kinetics: Carbon Diffusion

Decarburization is a diffusion-controlled process. When steel is at high temperatures, atoms gain higher mobility and carbon diffuses from regions of high concentration (core) to regions of lower concentration (surface). This process intensifies when the material is fully in the austenitic phase (above Ac₃), where carbon diffusivity is significantly higher.

The depth of the decarburized layer depends on temperature, exposure time, steel composition and furnace atmosphere conditions. This phenomenon is critical because the reduction of carbon content at the surface directly affects wear resistance and fatigue performance of the material.

Methods for Determining Decarburized Layer and Oxides

Prediction of Oxides Using Computational Tools

The use of tools like Thermo-Calc software allows the prediction of stable phases as a function of temperature and oxygen partial pressure. These diagrams enable identification of which oxides will form at the surface, evaluation of whether these oxides act as a barrier or facilitate carbon loss, and optimization of heat treatment conditions.

Figure 2. Thermodynamically stable phases formed during high-temperature oxidation as a function of oxygen activity for H11 steel at 600°C (1112°F) (Balaško, et al. 2021)

For example, in steels such as H11, phase stability diagrams allow visualization of how oxide formation varies as a function of temperature and oxygen activity (Figure 2). Understanding these relationships is key to preventing decarburization, designing controlled atmospheres, and avoiding undesirable mechanical property outcomes.

Determination of Decarburized Layer Depth

The ASTM E1077 standard establishes different methods to evaluate the depth of the decarburized layer, including microscopic methods, microhardness, and chemical analysis. These methods determine whether a component meets specifications and define the proper preparation required for hardness measurement. The following sections present an example of the use of these methods. The objective of this analysis was to determine the depth of this layer to generate internal instructions for proper sample preparation through grinding, ensuring accurate hardness measurements.

Experimental Methodology

Figure 3. QTC preparation for sample extraction. | Image credit: Consultoría Carnegie

A QTC sample of AISI 4340 steel in forged condition was selected and subjected to normalizing, quenching, and tempering. Samples were obtained through cross-sectional cutting to perform hardness testing, optical microscopy, and carbon chemical analysis (by LECO, Figure 3).

Results

Hardness Profile

Measurements were taken at 1 mm intervals from the surface toward the interior. The results showed 0–3 mm low hardness values (~30 HRC) and an increase up to 35–36 HRC at 5 mm, remaining constant (Figure 4). This indicates that the surface region does not represent the actual properties of the material.

Figure 5. a) Hardness evaluation zones every 1 mm, b) hardness results shown as a color map (blue represents the softer surface region and red represents the harder region at 5 mm depth). | Image credit: Consultoría Carnegie and Mikra QATM

One of the challenges in this method is the precision of hardness indentations. It can be observed in Figure 4b that a fine marker was used to define the measurement zones; however, nowadays the use of advanced equipment allows automated programming of measurement locations (Figure 5).

Chemical Analysis (LECO)

Figure 6. a) Carbon analysis results using a LECO system, b) sample used for carbon analysis. | Image credit: Consultoría Carnegie

The LECO analysis showed an increase in carbon percentage starting at approximately 5 mm depth, confirming the presence of a decarburized layer (Figure 6).

Optical Microscopy

The optical microscopy analysis allowed observing microstructural changes between the surface and the core associated with carbon loss (Figure 7).

Practical Application: Shop Floor Control

Table A. Work Instruction in the Hardness Testing Area

Based on the results, work instructions were established to ensure reliable hardness measurements (Table A).

Operational Implementation

It is essential to involve operational personnel in understanding these phenomena, explaining why proper surface preparation is critical, how it impacts hardness measurement, and how this helps prevent rework. Additionally, it must be considered whether the dimensions of the components allow such preparation. Otherwise, it is necessary to communicate possible deviations or limitations to the client.

This analysis should be conducted for different steel grades, as well as at different temperatures and processing times, in order to estimate the effect on decarburization depth. This will facilitate the implementation of preventive actions for the operational team, instructing them to avoid overheating the parts or exposing them in the furnace for prolonged periods.

Conclusion

It is highly recommended that heat treatment companies conduct this type of metallurgical study, since it allows a deeper understanding of the real behavior of their processes. As previously mentioned, the depth of the decarburized layer is influenced by multiple variables, which may impact each company differently depending on factors such as steel type, furnace type, and processing time, among others.

Based on the results, it is possible to establish clear guidelines for operators, specifically regarding the depth at which samples must be prepared or ground to ensure that hardness values reported to the client are accurate and representative. Likewise, these analyses can be extended to different steel grades, allowing the development of specific work instructions indicating the required grinding depth depending on the material and processing conditions.

Decarburization is a critical phenomenon in heat treatment processes that can lead to incorrect interpretation of hardness results. A comprehensive analysis combining metallurgical fundamentals, standard methodologies, computational tools, and process history allows avoiding unnecessary rejection, improving process control, and ensuring final product quality.

References

Balaško, T., Vončina, M., Burja, J., Šetina Batič, B., & Medved, J. 2021. High-Temperature Oxidation Behaviour of AISI H11 Tool Steel. Metals, 11(5), 758. https://doi.org/10.3390/met11050758.

Herring, Daniel H. 2014. Atmosphere Heat Treatment: Atmospheres, Quenching, Testing. Vol. 2. Troy, MI: BNP Media.

Juan Hou, Fen-Fen Han, Xiang-Xi Ye, Bin Leng, Min Liu, Yan-Ling Lu, Xing-Tai Zhou. 2019. Effect of Surface Decarburization on Corrosion Behavior of GH3535 Alloy in Molten Fluoride Salts[J]. Acta Metallurgica Sinica (English Letters). 32(3): 401-412. https://doi.org/10.1007/s40195-018-0814-5.

Krauss, George. 2015. Steels: Processing, Structure, and Performance. 2nd ed. Materials Park, OH: ASM International.

About The Author:

Ana Laura Hernández Sustaita
Founder
Consultoría Carnegie

Ana Laura Hernández Sustaita holds a Master’s degree in Materials Science and engineering. She is the founder of Consultoría Carnegie, a technical consulting and training firm specializing in steel heat treatment in Mexico. Additionally, she works as a technical support engineer at Thermo-Calc Software, providing assistance to clients across México, Canada, and United States of America. Ana actively promotes metallurgical education throughout Latin America and advocates for the integration of computational tools into industrial heat treatment practice.

For more information: Contact Ana Hernández at anahdz@consultoriacarnegie.com.

Decarburized Layer in Steel: Understanding, Evaluation, and Control Read More »

Capa descarburada en aceros: comprensión, evaluación y control

September 1, 2026 / HARDENING TECHNICAL CONTENT, HARDNESS TESTERS TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH

Los resultados de dureza inferiores a las especificaciones no siempre se deben a errores en el tratamiento térmico. En esta entrega de Technical Tuesday, Ana Laura Hernández Sustaita, fundadora de Consultoría Carnegie, analiza cómo se desarrolla la descarburización, cómo afecta a la dureza y a las propiedades superficiales, y los métodos prácticos que los técnicos de tratamiento térmico pueden utilizar para evaluarla, controlarla y prevenirla mediante análisis metalúrgicos y una estricta disciplina en el proceso.

Este artículo informativo se publicó por primera vez en Heat Treat Today’s July 2026 Annual Super Brands Issue print edition.

Si tiene comentarios o preguntas sobre este artículo, háganoslo saber en: editor@heattreattoday.com.

To read this article in English, click here.

Introducción: cuando los resultados no coinciden con la teoría

En operaciones de tratamiento térmico, los resultados de dureza fuera de especificación suelen atribuirse a desviaciones en los parámetros del proceso, errores operativos o variaciones en la composición química del material. Sin embargo, existen casos donde la causa raíz está relacionada con fenómenos metalúrgicos que afectan directamente la superficie del material.

Un caso representativo involucró una carga de diez piezas forjadas de más de 5 toneladas cada una, fabricadas en acero AISI 4340. El proceso térmico aplicado era conocido y previamente validado: normalizado, temple seguido de revenido en un rango de 600-610°C (1112–1130°F), con el objetivo de cumplir con las propiedades mecánicas requeridas por el cliente. Tras finalizar el tratamiento térmico, el equipo de inspección reportó valores de dureza de las piezas aproximadamente 20-30 HB por debajo de la especificación. Este resultado fue inesperado, considerando que el acero 4340, debido a su contenido de elementos aleantes, mantiene valores elevados de dureza incluso a temperaturas relativamente altas de revenido. Se solicitó una reevaluación de dureza, incrementando la profundidad de preparación de la superficie hasta 5 mm. Sin embargo, los valores de dureza únicamente aumentaron ligeramente (~5 HB), sin alcanzar los niveles requeridos.

Ante la presión por los tiempos de entrega, se decidió reprocesar las piezas. Se aplicó nuevamente el ciclo completo de tratamiento térmico, ajustando la temperatura de revenido a 580°C (1076°F), lo cual, desde el punto de vista metalúrgico, debería incrementar la dureza. No obstante, los resultados permanecieron prácticamente sin cambios. Se procedió a verificar la composición química mediante PMI, confirmando que el material correspondía efectivamente a un acero 4340. Adicionalmente, la pieza de evaluación “Qualification Test Cupon” (QTC) indicaba valores de dureza elevados, consistentes con el comportamiento esperado del material.

Ante la inconsistencia entre resultados experimentales, fundamentos metalúrgicos y la previa experiencia personal, se decidió profundizar en el análisis del historial del proceso y correlacionar las variables de cada uno de los procesos. Y aquí es donde se encuentra la clave de un buen análisis de fallas, el detallar el historial de la pieza con la que se está trabajando.

Se identificó que, previo al tratamiento térmico, las piezas habían permanecido dentro de un horno en un rango de 800-900°C (1472–1652°F) durante aproximadamente tres días, debido al retraso que el equipo de mantenimiento tenía en la máquina de rolado, debido a esto y a una falta de comunicación entre los operadores de turno, la pieza continuaba en espera en el horno de calentamiento a “baja temperaturas” para concluir su último paso. Aunque no fue a temperaturas de rolado, esta exposición prolongada en una atmósfera no controlada promovió la descarburización del material.

Para validar esta hipótesis, se realizó un corte longitudinal en una de las piezas y se llevaron a cabo mediciones de dureza en el núcleo. Los resultados confirmaron que el material presentaba valores significativamente mayores en el interior, evidenciando una capa superficial descarburada. Este caso demuestra la importancia de: Analizar integralmente la historia del material y del proceso antes de concluir con una no conformidad.

¿Qué es la descarburización?

Figura 1. Esquema representativo del proceso de descarburización y oxidación. | Referencia: Consultoría Carnegie

El acero es una solución sólida basada en hierro y carbono, donde las propiedades mecánicas dependen directamente del contenido de carbono y los elementos aleantes presentes. La descarburización es un fenómeno metalúrgico que consiste en la pérdida de carbono desde la superficie del acero cuando este es expuesto a altas temperaturas en atmósferas con potencial oxidante o bajo potencial de carbono (Figura 1). Este fenómeno ocurre comúnmente durante: forja, laminación en caliente, normalizado, recocido y tratamientos térmicos en hornos convencionales sin control de atmósfera.

Desde el punto de vista termodinámico, la descarburización ocurre cuando el potencial químico del carbono en el acero es mayor que el del ambiente circundante, lo que impulsa la difusión del carbono hacia la superficie. En presencia de gases oxidantes, el carbono reacciona formando especies gaseosas:

También puede reaccionar con vapor de agua o dióxido de carbono, lo que acelera el proceso. Como consecuencia: se genera un gradiente de carbono (superficie vs núcleo), se altera la microestructura, se degradan propiedades mecánicas, especialmente en la superficie.

Oxidación y su relación con la descarburización

La descarburización está estrechamente relacionada con los procesos de oxidación. La oxidación ocurre cuando el oxígeno reacciona con el metal formando óxidos en la superficie. Este proceso depende del equilibrio termodinámico entre las presiones parciales de los gases presentes, lo cual puede analizarse mediante diagramas como el de Ellingham-Richardson.

El incremento de la temperatura acelera tanto la oxidación como la descarburización, por lo que el uso de hornos con atmósfera controlada es fundamental para prevenir estos fenómenos.

Cinética del proceso: difusión del carbono

La descarburización es un proceso gobernado por difusión. Cuando el acero se encuentra a altas temperaturas los átomos adquieren mayor movilidad y el carbono difunde desde regiones de alta concentración (interior) hacia regiones de menor concentración (superficie). Este proceso se intensifica cuando el material se encuentra completamente en fase austenítica (por encima de Ac3), donde la difusividad del carbono es significativamente mayor.

La profundidad de la capa descarburada depende de: temperatura, tiempo de exposición, composición del acero y condiciones de la atmósfera del horno. Este fenómeno es crítico, ya que la reducción del contenido de carbono en la superficie afecta directamente la resistencia al desgaste y fatiga del material.

Métodos para la determinación de la capa descarburada y óxidos

Predicción de óxidos mediante herramientas computacionales

El uso de herramientas como Thermo-Calc software, permite predecir las fases estables en función de la temperatura y la presión parcial del oxígeno. Estos diagramas permiten identificar que óxidos se formarán en la superficie, evaluar si los óxidos actúan como barrera o facilitan la salida del carbono y optimizar las condiciones del proceso térmico.

Figura 2. Fases termodinámicamente estables formadas durante la oxidación a alta temperatura (600°C [1112°F]) en función de la actividad del oxígeno para el acero H11 (Balaško, et al. 2021)

Por ejemplo, en aceros como H11, los diagramas de estabilidad de fases permiten visualizar cómo varían los óxidos formados en función de la temperatura y la actividad de oxígeno (Figura 2). Comprender estas relaciones es clave para prevenir la descarburización, diseñar atmósferas controladas y evitar resultados no deseados en propiedades mecánicas.

Determinación de la profundidad de capa descarburada

La norma ASTM E1077 establece diferentes métodos para evaluar la profundidad de la capa descarburada, incluyendo: métodos microscópicos, microdureza y análisis químico. Estos métodos permiten determinar si una pieza cumple con las especificaciones y definir la preparación adecuada para medición de dureza. A continuación, se muestra un ejemplo del uso de los métodos. El objetivo de este análisis fue determinar la profundidad de esta capa para generar instrucciones internas para la preparación adecuada mediante del pulido de las piezas para la medición correcta de dureza.

Metodología experimental

Figura 3. Preparación de QTC para extracción de muestras para análisis. | Referencia: Consultoría Carnegie

Se seleccionó un QTC de acero AISI 4340 en condición forja, sometido a un ciclo de normalizado, temple y revenido. Las muestras se obtuvieron de un corte transversal para realizar el análisis de dureza, microscopía óptica y análisis químico de carbono (LECO, Figura 3).

Resultados

Perfil de dureza

Se realizaron mediciones a intervalos de 1 mm desde la superficie hacia el interior. Los resultados mostraron: 0–3mm valores bajos de dureza (~30 HRC), a 5 mm: incremento hasta 35–36 HRC, manteniéndose constante (Figura 4). Esto indica que la zona superficial no representa las propiedades reales del material.

Uno de los retos en este método es la precisión de las huellas de dureza, se puede observar como la muestra Figura 4b, se usó un marcador fino para determinar las zonas a medir, sin embargo, hoy en día el uso de equipos sofisticados nos permite realizar una programación automática de las zonas a evaluar (Figura 5).

Análisis químico (LECO)

Figura 6. a) Resultados de análisis de %C en un equipo LECO, b) muestra utilizada para análisis de %C. | Referencia: Consultoría Carnegie

El análisis mostró un incremento en el porcentaje de carbono a partir de aproximadamente 5 mm de profundidad, confirmando la existencia de una capa descarburada (Figura 6).

Microscopía óptica

Este análisis permitió observar cambios microestructurales entre la superficie y el núcleo, asociados a la pérdida de carbono (Figura 7).

Aplicación práctica: control en planta

Tabla A. Instrucción de trabajo en área de pruebas de Dureza

Con base en los resultados, se establecieron instrucciones de trabajo para asegurar mediciones confiables de dureza (Tabla A).

Implementación operativa

Es fundamental involucrar al personal operativo en la comprensión de estos fenómenos, explicando por qué es crítico el pulido adecuado, cómo impacta en la medición de dureza y cómo esto evitará retrabajos. Así mismo, se debe considerar si las dimensiones de las piezas permiten dicha preparación. En caso contrario es necesario comunicar al cliente posibles desviaciones o limitaciones en la medición.

Se recomienda llevar a cabo este análisis para los diferentes grados de aceros, temperaturas y tiempos de procesamiento, que ayude a estimar el efecto sobre la profundidad de capa descarburizada y con esto implementar acciones preventivas al equipo operativo sobre evitar un sobrecalentamiento o someter las piezas a periodos prolongados de tiempo en un horno.

Conclusión

Es altamente recomendable que las empresas dedicadas al tratamiento térmico lleven a cabo este tipo de estudios metalúrgicos, ya que estos permiten comprender con mayor profundidad el comportamiento real de sus procesos. Como se mencionó previamente, la profundidad de la capa descarburada está influenciada por múltiples variables, las cuales pueden impactar de manera distinta en cada empresa, dependiendo de factores como el tipo de acero, el tipo de horno utilizado, los tiempos de tratamiento entre otros.

A partir de los resultados obtenidos, es posible establecer lineamientos claros para los operadores, específicamente en relación con la profundidad a la que deben preparar o pulir las muestras, con el objetivo de asegurar que los valores de dureza reportados al cliente sean representativos y correctos. Así mismo estos análisis pueden desarrollarse para distintos grados de acero, permitiendo la generación de fichas o instrucciones de trabajo específicas para cada caso donde se indique de manera precisa la profundidad de pulido requerida en función del material y las condiciones de proceso.

La descarburización es un fenómeno crítico en procesos de tratamiento térmico que puede llevar a interpretaciones incorrectas de los resultados de dureza. El análisis integral que combine: Fundamentos metalúrgicos, normativas estándar, herramientas computacionales, historial del proceso, permite: evitar rechazos innecesarios, mejorar el control del proceso y asegurar la calidad del producto final.

Referencias

Balaško, T., Vončina, M., Burja, J., Šetina Batič, B., & Medved, J. 2021. High-Temperature Oxidation Behaviour of AISI H11 Tool Steel. Metals, 11(5), 758. https://doi.org/10.3390/met11050758.

Herring, Daniel H. 2014. Atmosphere Heat Treatment: Atmospheres, Quenching, Testing. Vol. 2. Troy, MI: BNP Media.

Krauss, George. 2015. Steels: Processing, Structure, and Performance. 2nd ed. Materials Park, OH: ASM International.

Acerca de la autora:

**Ana Lau**ra Hernández Sustaita
Fundadora
Consultoría Carnegie

Ana Laura Hernández Sustaita cuenta con Maestría en Ciencia e Ingeniería de los Materiales, Es fundadora de Consultoría Carnegie, una firma de consultoría y capacitación técnica especializada en el tratamiento térmico de aceros en México. Asimismo, se desempeña como Ingeniera de Soporte Técnico en Thermo-Calc Software, brindando asistencia a clientes en México, Canada y Estados Unidos de América. Ana promueve activamente la educación metalúrgica en Latinoamérica y fomenta la integración de herramientas computacionales en la práctica industrial del tratamiento térmico.

Para más información: Contacte con Ana Hernández en anahdz@consultoriacarnegie.com.

Capa descarburada en aceros: comprensión, evaluación y control Read More »

Answers in the Atmosphere: Industrial Gas Supplier Tech Support Part 2

August 26, 2026 / BULK GASES & SYSTEMS TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH, SINTERING POWDER/METAL TECHNICAL CONTENT

In this installment of Answers in the Atmosphere, David (Dave) Wolff, an independent expert focusing on industrial atmospheres for heat treat applications, examines what furnace owners should expect when their gas supplier conducts a technical assessment. Drawing on insights from Messer LLC, Wolff walks through the step-by-step process suppliers use to diagnose furnace atmosphere issues, from verifying process parameters to running detailed diagnostic surveys, and outlines the standards of technical competence, communication, and accountability that furnace owners should hold their industrial gas partners to.

This informative piece was first released in Heat Treat Today’s August 2026 Annual Automotive Heat Treating print edition.

This column picks up the conversation leveraging the technological know-how of your gas supplier. If you missed it, read Part 1 in the Heat Treat Super Brands (July 2026) print edition. What follows are the insights and best practices that Messer LLC shared with me on what you need to prepare for a technical assessment with your supplier.

Technical Assessment

First, since business models vary throughout the industry, be sure you understand whether or not technical support will entail a specific fee. When establishing your gas supply contract, furnace owners should seek out suppliers who provide a flexible approach that will be aligned with their needs.

A supplier will often follow these steps when providing technical support to identify, prevent, or correct issues in your heat treat furnace:

Define and verify the problem to determine whether it originates from heat treatment, material handling, or operator error.
Verify incoming material to ensure the issue is not caused by raw material condition or pre-processing steps.
Check heat treatment process control parameters.
Verify furnace atmosphere integrity, inspecting gas supply lines, furnace connections, piping leaks, deliveries, and any repairs.
Evaluate furnace component, identify any changes in furnace structure or maintenance activities.
Review process parameters to confirm whether temperature, time, gas composition, or gas purity have changed.
Inspect exhaust systems, doors, and airflow, as disturbances can impact furnace performance.

After reviewing initial process data, a furnace atmosphere survey or targeted spot check may be conducted. This step may include:

Establishing furnace baseline conditions
Running furnace temperature profile tests
Measuring oxygen, CO, CO₂, hydrogen content, and dew point
Conducting detailed modeling based on gas flows, heat transfer, or mass balances

Your provider may use advanced tools, such as Computational Fluid Dynamics (CFD) modeling, to analyze and resolve complex furnace atmosphere issues.

What to Expect: Evaluating Supplier Capabilities

Not all technical support delivers the same value. While many suppliers have strong technical capabilities, access can vary based on internal structures or business models. Some suppliers provide expanded support.

Furnace owners should expect their industrial gas partner to:

Demonstrate strong technical competence and ability to identify root causes
Communicate clearly in practical terms familiar to operations teams
Deliver recommendations with a complete implementation plan including safety, training, costs, timelines, risks, and benefits
Clearly define responsibilities between the furnace owner and gas provider

Final Thoughts

For furnace owners, the industrial gas supply space can seem like a lot of the same offerings, but a closer look at how technical support varies from one supplier to the next can significantly fine tune your operation’s ability to adapt and respond to your furnace needs. The key is to be honest about what your own operations can accomplish on its own before reviewing industrial gas contracts (more on contracts in the June 2026 “Answers in the Atmosphere” installment) and committing to a too low or too flexible plan for technical support.

About The Author:

David (Dave) Wolff
Industrial Gas Professional
Wolff Engineering

Dave Wolff has over 40 years of project engineering, industrial gas generation and application engineering, marketing, and sales experience. Dave holds a degree in engineering science from Dartmouth College. Currently, he consults in the areas of industrial gas and chemical new product development and commercial introduction, as well as market development and selling practices.

For more information: Contact Dave Wolff at Wolff-eng@icloud.com.

Main image shows piston rings being heat treated in a furnace using Messer’s HYDROPYR^TM technology for sintering. | Image Credit: Messer USA

Answers in the Atmosphere: Industrial Gas Supplier Tech Support Part 2 Read More »

Hidden Water, Hidden Risk: Preventing Quench Tank Fires

August 25, 2026 / ATMOSPHERE AIR FURNACES TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH, QUENCHING TECHNICAL CONTENT

A small amount of hidden water at the bottom of a quench tank can rapidly escalate into a violent fire hazard. In this Technical Tuesday installment, Bruno Scomazzon, general manager of Precision Heat Treat Ltd., discusses how free water develops, why conventional testing can miss it, and the practical steps heat treaters can take to detect and eliminate the risk.

This informative piece was first released in Heat Treat Today’s July 2026 Annual Super Brands Issue print edition.

Most heat treat shops never see the danger building beneath the surface of their quench oil. Drop by drop, water stratifies, tipping the balance and awakening the dragon.

In an integral quench furnace, quenching is a controlled process. When a hot load is submerged, vapor is generated below the surface, rising and mixing with the furnace atmosphere. Oil temperature, atmosphere, and vapor generation are managed so that any combustion remains contained, with gases and vapor generated and relieved in a controlled manner. Under normal conditions, the process is stable and predictable.

AI-generated illustration based on a potential quench fire scenario. No actual integral quench furnaces were harmed in the making of this article. | Image Credit: Precision Heat Treat Ltd.

Add water, and you introduce a completely different hazard. It can turn violent before you understand or can react to what you are seeing. In this scenario, when the hot load is submerged, water at the bottom of the tank flashes instantly to steam, expanding roughly 1,600 times in volume. That expansion happens almost instantly, and the resulting increase in volume overwhelms the system.

As the steam rises, each bubble becomes coated with oil. Rapid expansion displaces oil and generates a large volume of vapor in a very short period of time. In a confined quench chamber, that surge carries oil and vapor together toward the burn-off vent and the doors.

There are typically two doors in the system, and they behave very differently. The inner door separates the hot zone from the quench tank. During quenching, the hot zone is typically operating around 1550°F. If oil is forced into the hot zone, it will vaporize and burn, generating products of combustion that can lead to a more severe internal event. However, this is not where the external fire develops. The outer door separates the quench chamber from the outside. During a surge, oil and vapor push upon this door and can be forced out. When the flammable oil vapor and furnace atmosphere reach an ignition source such as the flame curtain pilot, it will ignite violently.

At that point, the fire is no longer confined or controlled. Oil that reaches the exterior can spread along the floor and around the base of the furnace. Once outside the chamber, any oil present becomes fuel, and the fire can spread quickly.

How Water and Oil Interact

Two different conditions exist: dissolved water and free water. Dissolved water is moisture within the oil, typically when the oil is hot. It is part of normal operation and must be monitored. Elevated dissolved water levels are mainly a performance and control problem, not the immediate hazard. But if it continues to rise, it leads to free water, which is the hazard. Free water is water that has separated from the oil and settled to the bottom of the tank.

As a general guideline for dissolved water:

Below 100 ppm (0.01%): very good
100–200 ppm (0.01–0.02%): acceptable
200–500 ppm (0.02–0.05%): caution range
Above 500 ppm (0.05%): corrective action required

These values apply to dissolved water in the oil — not the free water condition at the bottom of the tank, which is the condition of greatest concern. As the oil cools, its ability to hold moisture decreases. Excess water comes out of solution, forms small droplets, and over time settles to the bottom. This creates stratification — the formation of distinct layers. Oil floats above, leaving a layer of free water at the bottom. That bottom layer is the dangerous condition, the same condition that drives the surge event described earlier.

Water Does Not Just Appear — It Gets Introduced

Common water sources include condensation during shutdowns and startups, along with operator or maintenance oversights that allow water or contaminated oil to enter the system. On older units, water-cooled components can develop leaks over time, allowing water to enter the oil slowly and go unnoticed. Leaking roof components or failed hood caps can also allow water to reach the furnace and make its way into the tank.

Water does not always find its way into a quench tank through a leaking cooler, heat exchanger, or outside source. During extended shutdowns, particularly during cooler months or periods of high humidity, moisture can condense on the ceiling and sidewalls of the quench vestibule and tank area. As the furnace heats up and the colder oil tank lags behind, water droplets can form and eventually fall into the oil. | Image Credit: Precision Heat Treat Ltd.

Because this develops gradually and often out of sight, everyone in the shop needs to stay alert. If something does not look right, or behave abnormally, report it immediately.

Detecting Water: What the Operator Sees First

Detecting free water in a quench tank is not as straightforward as it sounds. In many cases, the first indication is not a test result but a change in furnace behavior.

Changes in burn-off flame height, flame recovery time, unusual oil discharge (“burping”), or abnormal sounds during quenching are often early warning signs that something in the system has changed. All furnace operators should be trained to recognize these changes and treat them as indicators that the condition of the quench may no longer be normal.

Confirming with Sampling and Testing

Most monitoring systems measure dissolved water in circulating oil — not free water at the bottom. That distinction matters. Water that is mixed in the oil can be measured and trended. Water that has separated and settled to the bottom may not be detected by standard sampling methods. A sample taken from a circulating line or mid-depth in the tank can show acceptable results while free water remains undetected. These values are typically determined through lab analysis or in-shop test kits that measure dissolved water in quench oil. Standard tank sampling does not distinguish between dissolved and free water. That is why where you take the sample matters as much as how you test it.

Bottom sampling is critical. Pulling oil from the lowest point in the tank after the furnace has been idle, such as over a weekend, is often the best way to identify free water. If you do not already have a way to sample from the bottom of your tank, you should plan to install a dedicated drain or sample port. A bottom sample should be part of your weekly oil monitoring.

In the absence of a dedicated bottom drain, a simple method can still be used. Tubing can be inserted down through the fill or access point until it reaches the bottom. By sealing the top of the tube, the oil column inside is held in place as it is withdrawn, allowing a sample from the lowest point in the tank. The sample must be taken before any agitation or circulation begins. If the oil has been disturbed, the water can be temporarily mixed and the true condition at the bottom may not be seen.

The sample is placed in a clear glass beaker and allowed to stand. If water is present in any significant amount, it will usually be obvious, especially when compared to a sample taken from mid-depth or circulating oil. If it is not obvious, a crackle test can be used as a quick field check. A small sample of oil is placed on a hot surface, typically around 300–350°F. If free water is present, it flashes to steam and produces visible bubbling or crackling.

In practice, the severity of the reaction gives a clear visual indication of the condition:

No reaction: acceptable, continue to run
Light fizz or fine bubbles: trace water present, monitor
Moderate crackle or popping: plan corrective action
Strong crackle or aggressive bubbling: correct the condition before continuing

A consistent reaction across samples is the key indicator. This is not a precise measurement, but it is a reliable field guide. If it is reacting hard, you are already past where you want to be.

Sending samples for quarterly lab analysis provides a more complete picture of oil condition, including water content, oxidation, viscosity, contamination, and quench performance. This helps track dissolved water levels and overall oil health. In-shop test kits and commercial monitoring systems are also available, but none replace the need to understand what is happening at the bottom of the tank.

Removing Free Water from the Quench Tank

When free water is present at the bottom of the tank, it must be removed. This is an immediate hazard. In practice, removing oil from the top-down is often the most controlled approach. Oil is siphoned from the surface, working downward and stopping about a foot above the bottom to avoid disturbing the settled water layer.

This allows clean oil to be removed first while leaving the water undisturbed. Attempting to remove water directly through a bottom drain is not always effective, particularly in larger tanks, as it can pull both water and usable oil and disturb the interface between the two.

Left: Accumulated oil sludge, soot, and scale deposits inside a quench tank. Right: The same area after cleaning. These deposits can build up over time and provide fuel for a fire. Regular tank cleaning is an often-overlooked part of quench oil stewardship and fire prevention. | Image Credit: Precision Heat Treat Ltd.

The removed oil can be placed into totes and allowed to sit undisturbed for several days so any remaining water can separate and settle. Clean oil can then be recovered from the top. The remaining oil and water mixture in both the tank and tote should be recycled. Other methods, such as vacuum dehydration or oil reclamation systems, can be used where available and are often more effective at removing both free and dissolved water, but are not always practical in every shop.

With the oil removed, this is an ideal time to carry out thorough tank cleaning. Over time, quench oils form sludge, a combination of oxidation byproducts, degraded oil, carbon, scale, and fines from processed parts. This material settles to the bottom, can trap and hold water, and hide it from normal sampling. As it builds up, it interferes with oil flow and agitation, affecting quench performance.

Tanks require periodic cleaning, typically every 12 to 18 months, depending on usage and condition. This is the time to remove sludge and clean deposits from the walls and ceiling.

It is also an opportunity to inspect agitation systems, elevators, rollers, and other components, and carry out preventative maintenance. Proper lockout procedures and confined space protocols must be followed.

The Bottom Line

Free water is an immediate hazard. If allowed to accumulate, it can trigger a rapid pressure event and an uncontrolled fire. Once it starts, it escalates quickly and is difficult to contain, putting personnel and the entire operation at risk.

Regular bottom sampling for free water must be part of your quality control.

Acknowledgements

The author would like to thank Daniel H. Herring, “The Heat Treat Doctor®” at The HERRING GROUP, Inc.

About The Author:

Bruno Scomazzon
General Manager
Precision Heat Treat Ltd.

Bruno Scomazzon is the general manager of Precision Heat Treat Ltd. in Surrey, British Columbia, Canada, with over 40 years of experience in metallurgical processes and heat treating operations.

For more information: Contact Bruno Scomazzon at bruno@precisionheattreat.com.

Hidden Water, Hidden Risk: Preventing Quench Tank Fires Read More »

Heat Transfer 101: The Basics

August 20, 2026 / BURNERS & COMBUSTION SYSTEMS TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH, OP-ED

Jim Roberts of U.S. Ignition engages readers in a Combustion Corner column about the basics of heat transfer — breaking down the First Law of Thermodynamics into practical terms for heat treaters, then using a real-world example to show how ambient load temperature can meaningfully shift BTU energy requirements and furnace performance.

This column was first released in Heat Treat Today’s July 2026 Annual Super Brands Issue print edition.

A furnace guy walks into a heat treat plant and says to the group of operators, “I just transferred here.” One of the furnace operators says, “Perfect, it’s what we do best.” Huh…? Well, of course they transfer heat. That’s what heat treaters do better than anyone else — we transfer heat. And the science of this transfer is called thermodynamics.

In the world of physics, there are four laws of thermodynamics, which are centered on the movement and flow of heat between objects. We’ll start with the concept of heat transfer, based on the First Law of Thermodynamics.

The concept of thermal conservation states that energy cannot be created or destroyed; it can only be transferred or transformed. In other words, whatever we put into the furnace in the form of heat will be the same amount that comes out or is absorbed. Additionally, the part we want to heat treat has thermal mass and therefore has heat as well. We say that the load is “cold,” but really, it’s normally coming into the process at room temperature, which means there is energy there that gives us a head start in heating it up.

Then, we know that the heat we feel from the shell of the furnace was not absorbed by the load but is part of the energy that we put into the furnace, it just wasn’t absorbed by the load. So, the heat exits the furnace into the room to be absorbed by other items that are not in equilibrium. The energy is always there, continuing on. It’s a wild concept, isn’t it?

Figure 1. The First Law of Thermodynamics | Image Credit: Jim Roberts

As shown in Figure 1, heat enters the furnace (designation “Q”). Heat then enters the work, which is designation “W” (e.g., load, furnace). Work absorbs most of the heat, but it also releases energy since it is starting to go towards a state of equilibrium, meaning heat in and heat released are equal. Then, the work releases energy into the area where it is not as hot and tries to heat it up and gain equilibrium. That’s the furnace guy standing there, the room, the building, etc. All of these things become the next stage of “work.”

So, when we get to the point of calculating the input (energy usage), we generally use BTU or KW ratings. We also must consider ambient temperature of the work because that Delta T, or temperature variance, is what we are having to account for. If that load is sitting at 70°F, it has value as a heat source, so we need to account for that. You will recall that the formula that is commonly used for calculating heat load is:

This will give you BTU requirements after you then apply an efficiency. Sometimes that’s an estimated efficiency. Let’s show the difference in that energy requirement that needs to be provided when the latent heat in the load is different.

Let’s suppose we are a heat treater in central Michigan. It’s December. We have been accustomed to staging our bulk parts for heat treating out on our open loading dock. The furnace is suddenly not performing like it did earlier in the year. It’s the same 1,000 lb load. Earlier in the year, our formula accounted for the 70°F load temperature coming in. Our equation would be:

In this example, if we bring the work in from the frozen loading dock at 20°F, the heat required jumps to 401,231 BTU energy required per hour. It’s not a lot, but the furnace will notice and not perform as well since the burners tend to run at a fixed setting.

Even slight variations can make a big difference in cost and performance. Simple and yet slightly confusing science is behind it all.

About The Author:

Jim Roberts president at U.S. Ignition, began his 45-year career in the burner and heat recovery industry focused on heat treating specifically in 1979. He worked for and helped start up WB Combustion in Hales Corners, Wisconsin. In 1985 he joined Eclipse Engineering in Rockford, IL, specializing in heat treating-related combustion equipment/burners. Inducted into the American Gas Association’s Hall of Flame for service in training gas company field managers, Jim is a former president of MTI and has contributed to countless seminars on fuel reduction and combustion-related practices.

For more information: Contact Jim Roberts at jim@usignition.com.

Heat Transfer 101: The Basics Read More »

Nitriding Selection Guide: Gas, Plasma, or Salt Bath?

August 11, 2026 / MANUFACTURING HEAT TREAT TECH, NITRIDING TECHNICAL CONTENT

Nitriding offers a unique combination of surface hardness, wear resistance, fatigue performance, and dimensional stability, making it a preferred thermochemical treatment for a wide range of industrial components. Readers will learn about the key benefits of nitriding, as well as the strengths and limitations of gas, plasma, and salt bath processes. In this Technical Tuesday installment, the aim of this guide by Daniel H. Herring, aka The Heat Treat Doctor®, and Dr. Edward Roliński, a senior scientist and recognized authority on plasma and ion nitriding, is to help engineers and heat treaters evaluate which nitriding technology best aligns with material requirements, case depth targets, and performance objectives.

This informative piece was first released in Heat Treat Today’s August 2026 Annual Automotive Heat Treating print edition.

Why Choose Nitriding?

Nitriding is a unique process that offers design engineers the ability to both predict and control the outcome of the heat treating process. The key advantage is that it significantly increases surface hardness, wear resistance, and fatigue life of component parts while minimizing dimensional change due to the low temperature nature of the process.

#1 Minimal Post-Processing

Nitriding can be used on a variety of component parts and metal forming tools made of steel or cast irons for applications in which wear, fatigue, or corrosion resistance is an important consideration. Steels, stainless steels, tool steels, powder metallurgy parts, and many other materials can be nitrided.

Table A. Recommended Ranges of Nitriding Potential (SAE International Aerospace Material Standard AMS 2759/10), latest revision
Notes:
1. Class 0: No white layer permitted on the surface of a nitrided part.
2. Class 1: 0.0127 mm (0.0005 inches) maximum white layer, 15% porosity or less.
3. Class 2: 0.0254 mm (0.001 inches) maximum white layer, 10%–50% porosity of the thickness of the white layer.

Dimensional change in nitriding is primarily governed by composition, tempering temperatures, time/temperature of nitriding, relative thickness of case/core, shape of the part, and areas masked off to prevent nitriding. The amount of growth is typically constant for identical parts nitrided in different batches by a fixed processing cycle. Most parts are nitrided in a two- or three-stage process and not ground after nitriding (Table A). This affords them excellent dimensional stability (Herring 2011). Once the amount of growth for a particular part has been established, allowances can be made during final machining (prior to nitriding) to ensure repeatable results.

By contrast, heat treating processes such as hardening or carburizing are performed at higher temperatures and result in dimensional and/or shape changes often requiring post-heat treat manufacturing steps (Roliński 2014). As such, the nitriding process has become an ever more popular choice.

#2 Case Depth Control

Nitriding as a thermochemical process is capable of producing a variety of case depths, an attribute affected by temperature, time, and nitriding potential (if there is not a compound zone formed). Caution should be used when stating a required case depth since a number of definitions for total case depth are in use. For this article, authors will use Table B to show how case depths are typically total case depths (core hardness + 50 HV0.5) that vary by material.

Table B. Typical Case Depths and Case Depth Ranges for Steels

For example, on an M2 tool steel, the case depth might vary between 25–100 µm (0.001”–0.004”). By contrast, 4140 or Nitralloy® can produce case depths in ranging from 100–500 µm (0.004–0.020”), with 305–380 µm (0.012–0.015”) being typical. For low/medium carbon steels and powder metal, white layer thickness may vary from 5µm–25 µm (0.0002”–0.001”) and is the overriding consideration.

#3 Enhancing Tribological Properties

Nitriding enhances various key tribological properties related to friction, wear resistance, lubrication interaction, and texture. These include improvement in sliding motion and reduced energy losses; wear characteristics involving resistance to adhesion, abrasion, fatigue, and corrosion; and lubrication, especially as it relates to load-carrying capacity, surface roughness, and surface texture/hardness.

#4 Nitriding Applications

The nitriding process can be used for surface hardening of both very small and very large parts (see lead image above and Figure 1). Typical examples are gears and shafts, stamping dies, piston rods, springs, pump housings, and welding tables. Dies are typically made of cast iron or tool steels, while gears and other powertrain components are made of alloy steels. All applications require precise control of the compound zone (i.e., white layer) thickness. If selective nitriding is required, areas are masked using a stop-off paint, or in plasma processes, mechanical masking is an option.

Figure 1. (a) A Bluco DD2040 modular welding table (double density hole pattern, 2m x 4m x 0.2m) after completion of gas nitriding heat treat cycle and post-processing; (b) A Bluco HD2040 modular welding table (high density hole pattern, 2m x 4m x 0.2m) being removed fro ma pit furnace following a gas nitriding heat treat cycle | Image Credit: Bluco

Figure 2. Typical nitrided surface appearance | Image Credit: Heat Treat Doctor®

Once finished, nitrided surfaces are typically smooth and grayish in appearance (Figure 2). If a “shiny” or “bright” surface or one of extremely low roughness is required, polishing methods can be used (e.g., superfinishing). The surface has high hardness, and is under residual compressive stress, which is critical in increasing bending fatigue and rolling contact fatigue (RCF) properties.

Gas, Plasma, Salt Bath

Table C. Comparison of Gas, Plasma/Ion, and Salt Bath Processes (Hemsath 2019)

There are three types of nitriding, each with their own strengths and limitations: gas, plasma/ion, and salt bath. Table C highlights these differences for immediate comparison. For a further breakdown of each process’s strengths, the authors have written unique articles exploring the three processes in greater depth, available on www.heattreattoday.com under each of the names:

Conclusion

Nitriding is a key technology to achieve heat treated results that modern manufacturing expects. But between gas, plasma, and salt bath, there are pros and cons to whichever method is chosen. Engineers need to assess what material needs and process outcomes are most significant to the outcome in order to select the right technology.

References

Boßlet, Jochim. n.d. Melonite®/QPQ Process Brochure. HEF Durferrit.

Hemsath, Mark K., and Daniel H. Herring. 2019. “Nitriding—Growth and Tribological Benefits for Surface Engineering.” In Heat Treating Progress 2019 Conference Proceedings. Materials Park, OH: ASM International.

Herring, Daniel H. 2011. “Principles of Gas Nitriding, Parts 1–4.” Industrial Heating, April–May.

Herring, Daniel H. 2013. “Masking Techniques, Part One.” Industrial Heating, April.

Herring, Daniel H. 2020. “An Overview of Nitriding—Technology and Tribological Benefits.” Industrial Heating, March.

Mittemeijer, Eric J., and Marcel A. J. Somers, eds. 2026. Thermochemical Surface Engineering of Steels. Elsevier.

Pye, David. 2003. Practical Nitriding and Ferritic Nitrocarburizing. Materials Park, OH: ASM International.

Resnick, Michael. n.d. “Private Correspondence.” HEF Durferrit USA. https://www.hefusa.net/salt_bath_nitriding_liquid_nitriding/overview.html

Roliński, E. 1987. “Effect of Plasma Nitriding Temperature on Surface Properties of Stainless Steel.” Surface Engineering 3: 35–40.

Roliński, E. 2004. “Ion Nitriding and Nitrocarburizing of Sintered PM Parts.” Industrial Heating, October: 33–35.

Roliński, E. 2005. “When and Why Ion Nitriding/Nitrocarburizing Makes Good Sense.” Industrial Heating, August: 67–72.

Roliński, E. 2005. “Negative Effects of Reactive Sputtering in Industrial Plasma Nitriding.” Journal of Materials Engineering and Performance 14 (3): 343–350.

Roliński, E. 2006. “Plasma Nitriding Automotive Stamping Dies.” Heat Treating Progress 6 (5): 19–23.

Roliński, E. 2014. “Plasma Assisted Nitriding and Nitrocarburizing of Steel and Other Ferrous Alloys.” In Thermochemical Surface Engineering of Steels, chap. 11, edited by E. J. Mittemeijer and M. A. J. Somers, 413–449. Cambridge, UK: Woodhead Publishing.

Roliński, Edward. 2024. “Practical Aspects of Sputtering and Its Role in Industrial Plasma Nitriding.” ASM Handbook Online Update, Vol. 5: Surface Engineering. Materials Park, OH: ASM International.

Roliński, E., J. Arner, and G. Sharp. 2005. “Negative Effects of Reactive Sputtering in Industrial Plasma Nitriding.” Journal of Materials Engineering and Performance 14 (3): 343–350.

Roliński, E., G. Sharp, and A. Konieczny. 2006. “Plasma Nitriding Automotive Stamping Dies.” Heat Treating Progress 6 (5): 19–23.

Roliński, E., and G. Sharp. 2004. “Ion Nitriding and Nitrocarburizing of Sintered PM Parts.” Industrial Heating, October: 33–35.

Roliński, E., and G. Sharp. 2005. “When and Why Ion Nitriding/Nitrocarburizing Makes Good Sense.” Industrial Heating, August: 67–72.

Roliński, E., and G. Sharp. 2017. “Controlling Plasma Nitriding.” Materials Performance and Characterization 6 (4): 698–716.

Roliński, E., J. Ludeman, J. McCain, V. Popovski, and M. Woods. 2021. “Nitriding Mechanisms of Ferrous Powder Metal Products in Gas, Salt, and Plasma Methods.” In Proceedings of PowderMet2021/AMPM2021/Tungsten2021, 330–337.

SAE International. n.d. AMS 2759/10 Aerospace Material Standard (latest revision).

Senatorski, J., J. Tacikowski, E. Roliński, and S. Lampman. 2017. “Tribology of Nitrided and Nitrocarburized Steels.” In ASM Handbook, Vol. 18: Friction, Lubrication, and Wear Technology, edited by George E. Totten, 638–652. Materials Park, OH: ASM International.

Spies, H. J., and A. Dalke. 2014. “Case Structure and Properties of Nitrided Steels.” In Comprehensive Materials Processing, edited by G. Krauss, Vol. 12, 439–488. Oxford, UK: Elsevier.

Winter, K. M., and J. Kalucki. 2013. “Gas Nitriding and Gas Nitrocarburizing of Steels.” In ASM Handbook, Vol. 4A: Steel Treating—Fundamentals and Processes, edited by Jon I. Dossett and George E. Totten, 647–679. Materials Park, OH: ASM International.

About The Authors

Dan Herring
(The Heat Treat Doctor®)
The HERRING GROUP, Inc.

Dan Herring, who is most well known as The Heat Treat Doctor^®, has been in the industry for over 50 years. He spent the first 25 years in heat treating prior to launching his consulting business, The HERRING GROUP in 1995. His vast experience in the field includes materials science, engineering, metallurgy, equipment design, process and application specialist, and new product research. He is the author of six books and over 1000 technical articles.

Dr. Edward Rolinski, affectionately known as “Doctor Glow,” is a distinguished senior scientist having spearheaded research on plasma/ion nitriding since the 1970s. He holds advanced degrees in manufacturing technology and metallurgy, including a PhD and Doctor of Science. His focus has been on plasma nitriding processes, especially involving titanium alloys and powder metallurgy. Over his career, Dr. Rolinski authored numerous influential technical chapters and articles, including for ASTM International and the ASM Handbook, and is a prolific contributor to industry publications. After decades of leadership and innovation in surface engineering and heat treating, he is now a consultant in the heat treating industry.

For more information: Contact Dan at dherring@heat-treat-doctor.com.

Nitriding Selection Guide: Gas, Plasma, or Salt Bath? Read More »

Why Choose Gas Nitriding?

August 10, 2026 / MANUFACTURING HEAT TREAT TECH, NITRIDING TECHNICAL CONTENT

Among today’s nitriding technologies, gas nitriding remains the most widely used process for enhancing surface hardness, wear resistance, and fatigue performance while preserving dimensional stability. In this Technical Tuesday installment, Daniel H. Herring, aka “The Heat Treat Doctor®,” and Dr. Edward Rolinski, a senior scientist and recognized authority on plasma and ion nitriding, explain where gas nitriding excels, its process advantages and limitations, and the applications best suited for the technology.

If you’re looking for a broader introduction, watch for the upcoming print feature, “Nitriding Selection Guide: Gas, Plasma, or Salt Bath?” for an overview of nitriding, its key benefits, and a side-by-side of the three primary nitriding processes.

Gas nitriding represents 60–70% of all nitriding processes. The main benefit of gas nitriding, specifically when compared to plasma nitriding, is its ability to harden the entire surface of the component. Masking can be done by copper plating or painting with a nitriding-specific stop-off paint (Figure 1). Modern gas nitriding processes also allow treating of stainless steel, where PVC and other chemicals are used for surface pre-activation. Maintenance increases when these activating agents are used.

Figure 1. Large steel pinions being prepared for nitriding | Image Credit: Nitrex

Figure 2. Typical small parts and loading arrangements for gas nitriding (Herring 2011)

Case depths are typically total case depths (core hardness + 50 HV0.5) and vary by material (see Table B in Herring et al. 2026). Caution should be used when stating a required case depth as a number of definitions for total case depth are in use.

Another benefit of using gas nitriding is its ability to form a thick compound zone up to 0.025 mm (0.001 inches). The process can enhance the corrosion resistance of steels, particularly combined with post-oxidation. Also, gas nitriding is an excellent way to improve tribological properties of the treated components (Senatorski et al. 2017). Modern controls allow for automatic process adjustment over the length of the cycle and control of the nitriding atmosphere based on nitriding potential (Kn value) or ammonia dissociation rate (Herring 2020; Winter and Kalucki 2013). This allows for precise growth of the compound zone type and thickness, tight case depth ranges, and repeatability.

Dimensional change in nitrided parts, typically very small, is governed largely by composition, tempering temperatures, time/temperature of nitriding, relative thickness of case/core, shape of the part, and areas masked off to prevent nitriding. The amount of growth is usually constant for identical parts nitrided in different batches by a fixed processing cycle. After the amount of growth for a particular part has been determined experimentally, allowance for it can be made prior to nitriding during final machining prior to nitriding.

Table A. Single Stage Gas Nitriding Case Depth Time at 525°C (975°F) (Herring 2011)

Sharp corners or edges should be avoided on parts to be nitrided, because the projections formed at sharp corners receive higher nitrogen concentration and are susceptible to brittleness and chipping. These sharp edges nitride through the section and are without support from a soft ductile core.

In the single stage process, a temperature range of 500°C–540°C (925°F–1005°F) is typical, and process times range from 1 to 100 hours (Table A). The dissociation rate of ammonia is held in the range of 15% to 30%. The process produces a brittle, nitrogen-rich white layer at the surface comprised of various iron nitrides (Fe2-3N, Fe4N). One advantage of this thick white layer is that it will provide longer component service life in abrasive and adhesive wear applications.

Most parts, however, are nitrided in a two- or even three-stage process and not ground after nitriding (Table C). This affords them excellent dimensional stability (Herring 2011). Case depth is affected by temperature (Figure 3), time (Figure 4), nitriding potential (if there is not a compound zone formed), and how the total case depth is defined.

Table B. Recommended Ranges of Nitriding Potential (SAE International Aerospace Material Standard AMS 2759/10)

Figure 3. Gas nitriding case depth versus time for 4140 steels at 538ºC (1000ºF) (Adapted from Stange Electronik GmbH Data)

Figure 4. Effect of temperature on formation of 0.51 mm (0.020 inches) case depth during nitriding 4140 steel (Adapted from Stange Electronik GmbH Data)

References

Herring, Daniel H. 2011. “Principles of Gas Nitriding, Parts 1–4.” Industrial Heating, April–May.

Herring, Daniel H. 2020. “An Overview of Nitriding—Technology and Tribological Benefits.” Industrial Heating, March.

Herring, Daniel H. and Edward Roliński. 2026. “Nitriding Selection Guide: Gas, Plasma, or Salt Bath?” Heat Teat Today, August.

SAE International. n.d. AMS 2759/10 Aerospace Material Standard (latest revision).

About The Authors

For more information: Contact Dan at dherring@heat-treat-doctor.com.

Why Choose Gas Nitriding? Read More »

Why Choose Plasma Nitriding?

August 10, 2026 / MANUFACTURING HEAT TREAT TECH, NITRIDING TECHNICAL CONTENT

As manufacturers look for greater control, precision, and flexibility in surface hardening, plasma nitriding has emerged as a versatile alternative to traditional nitriding methods. In this article, Daniel H. Herring, aka “The Heat Treat Doctor,” and Dr. Edward Rolinski, a senior scientist and recognized authority on plasma and ion nitriding, examine the advantages of plasma nitriding, including its ability to treat stainless steels, selectively harden complex geometries, and process powder metallurgy components.

Plasma nitriding can be used over a broad range of heat treating temperatures and is used for all types of ferrous alloys (Figures 1 and 2). Additionally, it has the ability to activate the surfaces of oxidized stainless steels to allow them to be nitrided (Winter and Kalucki 2013; Roliński 1987).

Figure 1. Plasma nitrided A-286 Alloy Marble’s Etchant | Image Credit: The Herring Group, Inc.

Figure 2. Plasma nitrided duplex stainless steel 2205 Marble’s Etchant | Image Credit: The Herring Group, Inc.

Activation of the surface involves both ion bombardment and sputtering of the surface/cathode in the areas where the glow discharge covers the surface (Figure 3). The actual contact area of the part with the cathodic base plate or fixture does not nitride. The problem of edge effect, which is related to uneven distribution of sputtered atoms at corners and edges of a component (Roliński et al. 2005; Roliński 2024), is addressed primarily by proper adjustment of the processing gas pressure, which changes the thickness of the cathodic glow, making it more uniform around contour of the part. Masking areas that do not need to be hardened is simple. For example, a nut on a thread or a steel plate on a section with small holes is sufficient to protect those surfaces from the glow discharge and prevent nitriding.

Figure 3. Typical “glow” around component parts during plasma nitriding | Image Credit: The Herring Group, Inc.

Figure 4. Plasma/Ion nitrided powder metal component run at 565°C (1050°F) in a mixture of nitrogen/hydrogen at a ratio of 1:3 and pressure 3.5 mbar. 3% Nital. (Roliński et al, 2021)

Plasma nitriding is a unique process capable of surface hardening low-density sinter/powder metal (PM) products, even those less than 7.3 g/cm3 (Figure 4) and PM stainless steels (Roliński 2004). This is especially true when a portion of the treated component requires masking (Roliński and Sharp 2005, 2004). Active nitrogen species generated by the glow discharge penetrate only near-surface cavities/porosities, forming a nitrided layer. By contrast, ammonia in gas nitriding penetrates throughout the entire thickness of the component increasing the brittleness of the nitrided part.

Plasma nitriding is a low-nitriding potential process because the compound zone/white layer is typically very thin without extreme control accuracy of the nitriding parameters. This is a result of sputtering and a low partial pressure of nitrogen during processing (Roliński 2014). Plasma nitriding requires much less processing gases, such as nitrogen and hydrogen, than gas nitriding with ammonia. In addition, only small quantities of hydrocarbon gases are needed to dope the atmosphere and form epsilon-type compound zones at the surface (Roliński and Sharp, 2004).

Long parts, such as extruder screws and shafts, can be plasma nitrided even in “cold-wall vessels,” which do not have external heaters (Hemsath and Herring 2019).

References

Herring, Daniel H. and Edward Roliński. 2026. “Nitriding Selection Guide: Gas, Plasma, or Salt Bath?” Heat Teat Today, August.

Roliński, E. 1987. “Effect of Plasma Nitriding Temperature on Surface Properties of Stainless Steel.” Surface Engineering 3: 35–40.

Roliński, E., J. Arner, and G. Sharp. 2005. “Negative Effects of Reactive Sputtering in Industrial Plasma Nitriding.” Journal of Materials Engineering and Performance 14 (3): 343–350.

Roliński, E., and G. Sharp. 2004. “Ion Nitriding and Nitrocarburizing of Sintered PM Parts.” Industrial Heating, October: 33–35.

Roliński, E., and G. Sharp. 2005. “When and Why Ion Nitriding/Nitrocarburizing Makes Good Sense.” Industrial Heating, August: 67–72.

Roliński, E. 2014. “Plasma Assisted Nitriding and Nitrocarburizing of Steel and Other Ferrous Alloys.” In Thermochemical Surface Engineering of Steels, edited by E. J. Mittemeijer and M. A. J. Somers, 413–449. Cambridge, UK: Woodhead Publishing.

About The Authors

For more information: Contact Dan at dherring@heat-treat-doctor.com.

Why Choose Plasma Nitriding? Read More »

Why Choose Salt Bath Nitriding?

August 10, 2026 / MANUFACTURING HEAT TREAT TECH, NITRIDING TECHNICAL CONTENT

For applications requiring exceptional wear resistance, corrosion protection, and rapid processing, salt bath nitriding continues to be a reliable surface engineering solution. In this article, Daniel H. Herring, aka “The Heat Treat Doctor,” and Dr. Edward Rolinski, a senior scientist and recognized authority on plasma and ion nitriding, explain how salt bath nitriding can create a durable compound layer that helps parts last longer and perform better across a wide range of industrial applications.

Salt bath nitriding, like gas nitriding, has been around for a very long time and is still in active use today. This method introduces nitrogen, and sometimes carbon, into the surface layer of steels, cast iron, and sintered powder metal by immersing the part in a molten salt bath containing nitrogen-bearing salts at elevated temperatures. The process enhances wear resistance, fatigue strength, corrosion resistance, and surface hardness without significantly affecting the core mechanical properties of the base material.

Salt bath nitriding has ability to form a thick compound zone up to 0.025 mm (0.001 inches). The process can enhance the corrosion resistance of steels, particularly when combined with post-oxidation. Also, salt bath nitriding is an excellent way to improve tribological properties of the treated components (“Melonite®/QPQ Process,” HEF USA).

A diverse range of industries and products leverage this process (e.g., automotive, aerospace, oil & gas; hydraulic and pneumatic machinery, firearms, metal forming and forging tools, material handling equipment, and tooling). Components like camshafts, gears, piston pins, hydraulic systems, and cutting tools benefit from the enhanced surface properties imparted by this process.

Salt bath nitriding is performed at temperatures typically ranging from 500°C to 630°C (930°F to 1165°F) to produce a controlled and highly uniform release of nitrogen at the surface of the workpiece (Figure 1). Nitrogen diffuses into, and chemically combines with, nitride-forming elements in the metal, producing a tough, ductile compound layer with exceptional mechanical properties through a catalytic reaction. This hard compound layer has wear properties that are reportedly 200% to 1000% greater than the original material, and greatly enhanced resistance to corrosion, galling, and scuffing (Pye, 2003).

Figure 1. Salt bath nitriding modifies the surface metallurgy and properties (“Salt Bath Nitriding, Controlled Liquid Nitriding (Overview),” HEF USA)

The salt reacts with the metal surface to form a hardened compound layer (primarily composed of ε-iron nitride and γ’-iron nitride) and a diffusion zone beneath it where nitrogen atoms diffuse into the metal matrix (Figure 2).

Figure 2. Microstructure of a sale bath nitrided component (“Salt Bath Nitriding, Controlled Liquid Nitriding (Overview),” HEF USA)

Case depth is a function of both treatment time and material. The final surface hardness is a function of the material composition. Higher percentages of nitride forming elements (Cr, Mo, Al, V, Mn, Ti, W) produce higher surface hardnesses (Table A).

Table A. Surface Hardness as a Function of Material (“Melonite®/QPQ Process,” HEF USA)

Salt bath nitriding remains a valuable surface engineering technique due to its effectiveness in enhancing durability, wear resistance, and corrosion performance. While environmental and safety concerns exist, advancements in salt chemistry and waste management continue to make this process viable for modern industrial applications.

References

Boßlet, Jochim. n.d. Melonite®/QPQ Process Brochure. HEF Durferrit.

Herring, Daniel H. and Edward Roliński. 2026. “Nitriding Selection Guide: Gas, Plasma, or Salt Bath?” Heat Teat Today, August.

Pye, David. 2003. Practical Nitriding and Ferritic Nitrocarburizing. Materials Park, OH: ASM International.

About The Authors

For more information: Contact Dan at dherring@heat-treat-doctor.com.

Why Choose Salt Bath Nitriding? Read More »

OMG Site Tour: An Inside Look at In-House Heat Treating

August 4, 2026 / ATMOSPHERE AIR FURNACES TECHNICAL CONTENT, HARDENING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH

This Technical Tuesday installment summarizes the highlights from a site visit by Heat Treat Today’s Doug Glenn, publisher and founder, and Karen Gantzer, manager of events. Learn how OMG Building Products, LLC took control of efficiency, product quality, and R&D in the middle of New England.

This informative piece was first released in Heat Treat Today’s July 2026 Annual Super Brands Issue print edition.

In 2003, OMG‘s decision to vertically integrate manufacturing operations meant that heat treating needed to be brought in-house, making R&D a prized cornerstone of operations that guarantee high quality products. The Northeast operation in Agawam, Massachusetts, now moves 20 million pounds of steel per year (two to three tractor trailer trucks of steel wire per day) and features electrically powered IQ batch furnaces and continuous mesh belt furnaces.

Founding and Evolution

Five guys in Agawam, Massachusetts, gathered around a backyard BBQ in 1981 talking about the challenge of finding decent roofing screws. Pooling their talents across fabrication, finance, and more, they formed the company that has expanded to be OMG Building Products LLC. Their singular focus: making better roofing fasteners. To this day, roofing fasteners still make up 60% of OMG’s business.

In 2003, following years of sustained growth and product expansion, they took steps to bring increased oversight to their product. The main objective was to further ensure quality, gain greater material velocity, and increase customer service. The first step was to invest in an ECoat painting line for the fasteners, the process closest to OMG’s clients. Kevin Walters, now OMG’s senior process engineering manager, was hired as quality manager to oversee these transitions.

Making room for roofing heat treating operations soon followed, as well as several building expansions in the industrial park, including a residential construction fastener business and increased warehouse space. These capacity developments brought OMG’s low-carbon steel and yet highly efficient roofing product to a global market.

The Next Step: In-House Heat Treat

Bringing heat treating in-house would be a major move to further secure the manufacturing line. Product was being shipped to as many as ten different locations, including facilities in the Midwest and Canada. In fact, the biggest percentage was at risk since that Waterbury, Connecticut, heat treat supplier was looking at closing its doors with just a 90-days’ notice.

It was 2012 when OMG decided to investigate installing systems at the industrial park in Agawam. After three to four years’ worth of technical and business research, the parent company approved the funds to embark on the installation that is there today.

Research and Design

Jeff Hotham, Heat Treat Manager, and Kevin Walters, R&D Lead, collaborate to make OMG’s heat treat operations more efficient and effective. | Image Credit: **Heat Treat** **Today**

When it comes to the success of their heat treat operations, Jeffrey (Jeff) Hotham, OMG heat treat manager, put it bluntly: “Kevin is our secret weapon.” Since joining the team in 2003 at the apex of change, the senior process engineering manager brought heat treating operations in-house, facing every obstacle that comes with it.

The first challenge was logistics. OMG is situated in a light industrial park that cannot provide enough energy to power gas or electric furnace operations. After much analysis, it was determined that the most cost-efficient solution was to build an electric line connecting to an Eversource utility grid. This has had welcome maintenance implications as the electrically powered furnaces do not require an on-site burner tech and the accompanying nickel element ceramic tubes are also low maintenance.

Next was determining the thermal processing equipment. For an entire year, Kevin researched heat treating methods to optimize the company’s fasteners. His boots-on-the-ground research included visiting commercial heat treat facilities, attending trade shows, and speaking directly with industry professionals.

Because OMG produces a variety of lengthy fasteners, distortion control drove the decision of an integral quench furnace design, while productivity needs were met through a continuous mesh belt furnace design. Additionally, size of the furnace systems was all important in balancing flexibility and time-to-market realities. This resulted in a competitive heat treat system design that would leverage a significant amount of automation and a loading system that minimized manual intervention. This original furnace line included two endo generators, smart oil filtration, cooling equipment, and material handling.

The Right Fit: Finding a Furnace OEM

The competitive system design, however, would hinge on the ability to find a vendor who could deliver dependable, customizable equipment. Kevin and a cross-functional team of OMG business, operations, finance, purchasing, and safety representatives were tasked with selecting the equipment supplier.

When reviewing their options, OMG’s choice of furnace supplier came down to three key factors: design flexibility, locality, and customer service. It was essential that the system integrate design decisions to accommodate Kevin’s researched solutions.

Some furnace OEMs had reservations about adapting their systems to accommodate these special requests. Other suppliers had systems completed at various locations, with features sometimes being subcontracted off-site. Ultimately, the team found their perfect fit with Williams Industrial Service, located in Bowling Green, Ohio, who were eager to accommodate design changes, maintained full control of furnace build under one roof, and demonstrated a service-minded team.

Once ordered, the next step was to monitor job progress. OMG was proactive, providing timeline-focused goals. The furnace build progressed on schedule with Kevin making quarterly visits to complete milestone reports.

Within three years, OMG’s full heat treating line was installed.

Optimizing Productivity in Current Operations

Operations have increasingly shifted to focus on cost savings and control over inefficiencies. From a 30,000-foot view, wire arrives, is skim drawn, goes through cold forming, then heat treating, and finally painting and packing.

Facility design is critical in operational performance. According to Kevin, the working environment surpasses that of many heat treat operations he has visited, a credit to how well Jeff manages the plant floor. A key example of this is safety. OMG’s safety culture can be seen throughout their operations, extending to the racking department where a climate-controlled room away from loud manufacturing supports racking staff. Kevin also remarked that the air ventilation system is a point of pride: “We literally have guys wear hoodies in the heat treat department in the wintertime… because we have so much fresh air intake and exhaust in the room; the climate here is pretty good.”

Mesh belt line | Image Credit: **Heat Treat** **Today**

When roofing fasteners are heat treated, they either go through one of the three medium- to large-scale continuous mesh belt furnace lines or through the automated integral quench (IQ) furnace line. The mesh belt line receives shorter, 1.5- to 6-inch parts that are poured from a tub onto the belt with ease as well as longer 7- to 8-inch product. On the other hand, the IQ furnace line includes two furnaces which receive longer parts up to 24 inches long from a fully automated delivery system; fasteners are hung from their heads on the rack to prevent distortion. In the future, the team looks forward to automating this part of the process.

Kevin Walters, Doug Glenn, Karen Gantzer, and Jeff Hotham stand in OMG’s testing lab. | Image Credit: **Heat Treat** **Today**

Long roofing screws are hand-racked to best control distortion. | Image Credit: **Heat Treat** **Today**

The IQ line is a point of pride. Kevin commented that he has reason to believe that his IQ line may be the most automated in the country. “My operators do not have to get on a charge cart at all,” he explains, “[because] it’s fully automated; it knows when loads are done in the furnaces, takes them, puts them in, takes them out, puts them in the washer, and takes them out. Everything is automatically programmed.” These loads are monitored based on weights for baskets and piece count for racks.

Jeff and Kevin have collaborated to increase equipment efficiency and throughput while maintaining quality.

Operations feature an in-house laboratory to test product, particularly for distortion, the leading quality concern for roofing product. As mentioned earlier, furnace line automation is a goal, yet longer parts — like thin-shanked 8-inch parts — may still need to be hand-racked on the mesh belt to attain the quality results.

The Power of Planned Maintenance

Regular planned maintenance schedules work to keep this operation up and running. Jeff coordinates any maintenance requiring extended furnace downtime to occur at the same time.

On an annual basis, temperature uniformity is prioritized through extensive furnace care, including replacing the thermocouples and carbon probes. As Jeff asserts, “We try to stay ahead of the game.” This planned maintenance takes two weeks of the furnace being out of commission to ensure the furnace is thoroughly cleaned and any equipment replacements completed.

Biannually (twice every year), furnace ductwork is cleaned — a critical measure to stop risk of fire since, according to Jeff, most industry fires start in the ducts. OMG outsources experts to complete this maintenance over the course of a full week.

Finally, on a quarterly basis, all equipment undergoes vibration and infrared analysis. Following this proactive maintenance schedule has brought the operation from producing 9 million pounds in his first year to 19.2 million pounds just six years later in 2025 — same equipment, simply leveraged by Jeff’s proactive planning and coordinating Kevin’s R&D efficiency endeavors.

Future

Kevin Walters, the R&D manager at OMG, explains how OMG forms spools into screw and nail roofing product to Doug Glenn, publisher of **Heat Treat** **Today**. | Image Credit: **Heat Treat** **Today**

As the business grows, OMG is exploring other ways to accomplish tasks better and more efficiently: induction, vacuum furnace, continuous or pass-through IQ, and rack furnaces are all being considered.

Kevin addressed their laser-focused approach in heat treating operations, saying, “As time goes on though, we are perfecting productivity with Kaizen events and controlling our own destiny and lowering overall costs. Last year, process optimization on the mesh belt lines boosted our productivity by more than 30% and our automated IQ line is up 20% this year.”

OMG’s operation demonstrates what curious innovation and on-the-ground industry research can unlock for in-house heat treating. If the past is any indication of the future, we’ll see OMG leading the way in thoughtful, quality-focused integration of advanced technology in the industry.

This article was written by Heat Treat Today’s editorial team. For more information, contact editor@heattreattoday.com.

OMG Site Tour: An Inside Look at In-House Heat Treating Read More »

MANUFACTURING HEAT TREAT TECH

Introduction: When Results Do Not Match Theory

What Is Decarburization?

Oxidation and Its Relationship with Decarburization

Process Kinetics: Carbon Diffusion

Methods for Determining Decarburized Layer and Oxides

Prediction of Oxides Using Computational Tools

Determination of Decarburized Layer Depth

Experimental Methodology

Results

Hardness Profile

Chemical Analysis (LECO)

Optical Microscopy

Practical Application: Shop Floor Control

Operational Implementation

Conclusion

References

About The Author:

Introducción: cuando los resultados no coinciden con la teoría

¿Qué es la descarburización?

Oxidación y su relación con la descarburización

Cinética del proceso: difusión del carbono

Métodos para la determinación de la capa descarburada y óxidos

Predicción de óxidos mediante herramientas computacionales

Determinación de la profundidad de capa descarburada

Metodología experimental

Resultados

Perfil de dureza

Análisis químico (LECO)

Microscopía óptica

Aplicación práctica: control en planta

Implementación operativa

Conclusión

Referencias

Acerca de la autora:

Technical Assessment

What to Expect: Evaluating Supplier Capabilities

Final Thoughts

About The Author:

How Water and Oil Interact

Water Does Not Just Appear — It Gets Introduced

Detecting Water: What the Operator Sees First

Confirming with Sampling and Testing

Removing Free Water from the Quench Tank

The Bottom Line

Acknowledgements

About The Author:

About The Author:

Why Choose Nitriding?

#1 Minimal Post-Processing

#2 Case Depth Control

#3 Enhancing Tribological Properties

#4 Nitriding Applications

Gas, Plasma, Salt Bath

Conclusion

References

About The Authors

References

About The Authors

References

About The Authors

References

About The Authors

Founding and Evolution

The Next Step: In-House Heat Treat

Research and Design

The Right Fit: Finding a Furnace OEM

Optimizing Productivity in Current Operations

The Power of Planned Maintenance

Future

Our Brands

Company