voestalpine Fastening Systems, a supplier to the railway industry, is bolstering its hardening processes of steel parts with a technological line consisting of multiple furnaces and washers. The process will be carried out in a protected nitrogen atmosphere with temperatures up to 1742°F (950°C) on parts to be used in railway rolling stock.
Mariusz Raszewski Deputy Director of Aluminum Process and CAB Furnaces SECO/WARWICK
The technological line on order from SECO/WARWICK consists of two CaseMaster furnaces, three tempering furnaces, and two washers. In addition, the railway supplier will have an electric chamber, a cooling station, and an endothermic atmosphere generator delivered.
“[T]he result of technological tests carried out in a service hardening plant that the customer was acquainted with … convinced voestalpine Fastening Systems that we would meet the high requirements of the contract. The line is configured in such a way that if the volume of the company products decreases, the customer can also offer commercial processing due to the wide technological spectrum of this main furnace unit,” said Mariusz Raszewski, deputy director of the Aluminum Process and CAB Furnaces Team at SECO/WARWICK.
The technological line will include a loader operating in automatic mode, a set of roller tables, and a closed-loop water system. The number of the supplied technological line units is selected to ensure the quality of manufactured components. The whole process will be supervised by a master system, which is used to continuously monitor the heat treatment equipment operation and provides advanced data analysis for the production processes.
Mariusz Fogtman Chief Operating Officer voestalpine Fastening Systems
“The universal furnace solution will allow [the client] to process various parts in various configurations. Apart from technological parameters, it is important for us to limit processed part deformations, which is possible with the solution on order,” said Mariusz Fogtman, chief operating officer, voestalpine Fastening Systems Sp. z o. o.
This is the first cooperation between both partners in this product area. SECO/WARWICK has previously delivered vacuum furnaces to the voestalpine Group.
Press release is available in its original from here.
The Heat Treat Doctor® has returned to offer sage advice to Heat Treat Today readers and to answer your questions about heat treating, brazing, sintering, and other types of thermal treatments as well as questions on metallurgy, equipment, and process-related issues.
This informative piece was first released in Heat Treat Today’sFebruary 2025 Air/Atmosphere Furnace Systems print edition.
People often ask two fundamental questions related to normalizing. First, is it necessary? Second, just what and how important is a “still air” cool to the end result? Let’s learn more.
Why Normalize?
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Normalizing is typically performed for one or more of the following reasons:
To improve machinability
To improve dimensional stability
To produce a homogeneous microstructure
To reduce banding
To improve ductility
To modify and/or refine the grain structure
To provide a more consistent response when hardening or case hardening
For example, many gear blanks are normalized prior to machining so that during subsequent hardening or case hardening dimensional changes such as growth, shrinkage, or warpage will be better controlled.
Normalizing imparts hardness and strength to both cast iron and steel components. In addition, normalizing helps reduce internal stresses induced by such operations as forging, casting, machining, forming or welding. Normalizing also improves chemical non-homogeneity, improves response to heat treatment (e.g., hardening), and enhances dimensional stability by imparting into the component part a “thermal memory” for subsequent lower temperature processes. Parts that require maximum toughness and those subjected to impact are often normalized. When large cross sections are normalized, they are also tempered to further reduce stress and more closely control mechanical properties.
Large paper roll normalized in a car bottom furnace and cooled (due to its mass) using the assistance of a floor fan.
Soak periods for normalizing are typically one hour per inch of cross-sectional area but not less than two hours at temperature. It is important to remember that the mass of the part or the workload can have a significant influence on the cooling rate and thus on the final microstructure. Thin pieces cool faster and are harder after normalizing than thicker ones. By contrast, after furnace cooling in an annealing process, the hardness of the thin and thicker sections is usually about the same.
Micrograph of medium-carbon AISI/SAE 1040 steel showing ferrite grains (white etching constituent) and pearlite (dark etching constituent). Etched in 4% picral followed by 2% nital. (Bramfitt and Benscoter, 2002, p. 4. Reprinted with permission of ASM International. All rights reserved.)
When people think of normalizing, they often relate it to a microstructure consisting primarily of pearlite and ferrite. However, normalized microstructures can vary and combinations of ferrite, pearlite, bainite, and even martensite for a given alloy grade are not uncommon. The resultant microstructure depends on a multitude of factors including, but not limited to, material composition, part geometry, part section size, part mass, and cooling rate (affected by multiple factors). It is important to remember that the microstructure achieved by any given process sequence may or may not be desirable depending on the design and function of the component part.
The microstructures produced by normalizing can be predicted using appropriate continuous cooling transformation diagrams and this will be the subject of a subsequent “Ask The Heat Treat Doctor” column.
In this writer’s eyes, industry best practice would be to specify the desired microstructure, hardness, and mechanical properties resulting from the normalizing operation. Process parameters can then be established, and testing performed (initially and over time) to confirm/verify results.
In many cases, the failure of the normalizing process to achieve the desired outcome centers around the lack of specificity (e.g., engineering drawing requirements, metallurgical and mechanical property call outs, testing/verification practices, and quality assurance measures). Failure to specify the required microstructure and mechanical properties/characteristics can lead to assumptions on the part of the heat treater, which may or may not influence the end result.
“Normalizing is the heat treatment that is produced by austenitizing and air cooling, to produce uniform, fine ferrite/pearlite microstructures in steel … In light sections, especially in alloy hardenable steels, air cooling may be rapid enough to form bainite or martensite instead of ferrite and pearlite.”
What Is Normalizing?
The normalizing process is often characterized in the following way: “Properly normalized parts follow several simple guidelines, which include heating uniformly to temperature and to a temperature high enough to ensure complete transformation to austenite; soaking at austenitizing temperature long enough to achieve uniform temperature throughout the part mass; and cooling in a uniform manner, typically in still air” (Herring, 2014).
It is also important to remember that normalizing is a long-established heat treatment practice. As far back as 1935, Grossmann and Bain wrote:
Normalizing is the name applied to a heat treatment in which the steel is heated above its critical range (that is, heated to make it wholly austenitic) and is then allowed to cool in air.
Since this is one specific form of heat treatment, it will be realized that the structure and mechanical properties resulting from the normalizing treatment will depend not only on the precise composition of the steel but also on the precise way in which the cooling is carried out.
The term ‘normalizing’ is generally applied to any cooling ‘in air.’ But in reality, this may cover a wide range of cooling conditions, from a single small bar cooled in air (which is fairly rapid cooling) to that of a large number of forgings piled together on a forge shop floor … which is a rather slow cool, approaching an anneal. The resulting properties in the two cases are quite different.
In plain carbon steels and in steel having a small alloy content, the air-cooled (normalized) structure is usually pearlite and ferrite or pearlite alone … More rapid cooling gives fine pearlite, which is harder; slow cooling gives coarse pearlite, which is soft. In some few alloy steels, the normalized structure in part may be bainite.
The hardness of normalized steels will usually range from about 150 to 350 Brinell (10 to 35 Rockwell C), depending on the size of the piece, its composition and hardening characteristics.
Importance of Defining Cooling Rate
In 2005, Krauss underscored the importance of defining cooling rate when he wrote: “Air cooling associated with normalizing produces a range of cooling rates depending on section size [and to some extent, load mass]. Heavier sections [and large loads] air cool at much lower cooling rates than do light sections because of the added time required for thermal conductivity to lower temperatures of central portions of the workpiece.”
Microstructures Created by Normalizing
The microstructural constituents produced by normalizing for a particular steel grade can be ferrite, pearlite, bainite, or martensite. The desired microstructure from normalizing adds an important cautionary note, as addressed by Krauss in STEELS (1990 and 2005), namely: “Normalizing is the heat treatment that is produced by austenitizing and air cooling, to produce uniform, fine ferrite/pearlite microstructures in steel … In light sections, especially in alloy hardenable steels, air cooling may be rapid enough to form bainite or martensite instead of ferrite and pearlite.”
Next time: We define a “still air” cool and look at the state of normalizing in North America.
Practical Data for Metallurgists, 17th ed. TimkenSteel.
Totten, George E., ed. Steel Heat Treatment Handbook, vol. 2, 2nd ed., CRC Press, 2007. 612-613.
About the Author
Dan Herring “The Heat Treat Doctor” The HERRING GROUP, Inc.
Dan Herring has been in the industry for over 50 years and has gained vast experience in fields that include materials science, engineering, metallurgy, new product research, and many other areas. He is the author of six books and over 700 technical articles.
A provider in the power solutions industry has enhanced its operations with a heat treat drop-bottom furnace for the solution heat treatment of aluminum castings. This installation will increase the company’s production capabilities, with the furnace having a load setting of 48 in (123 cm) wide x 36 in (91 cm) high x 141 in (358 cm) long.
The furnace, the fifth designed and manufactured by NUTEC Bickley, has a single temperature control zone, typically operating at 1000°F (573°C), with a maximum of 1075°F (580°C). The load setting will accommodate up to three baskets, equivalent to around 3600 lb (1635 kg) of aluminum parts per cycle. The furnace has been customized to be indirect gas-fired using radiant tube burners. Additionally, the project incorporates a motorized quench tank, rails, movement system, and load/unload platform with elevator device.
Arturo Arechavaleta Vice President, Metal Furnaces NUTEC Bickley
“Efficient and effective solution heat treatment is a vital part of the aluminum casting process,” said Arturo Arechavaleta, vice-president of Metal Furnaces at NUTEC Bickley. “Without the sort of advanced system that we have custom-designed, volume production of high-quality aluminum parts is not feasible. We’re proud to have played an important role in this technology partnership.”
The indirect gas firing is via single centrifugal recirculation that produces a vertical flow pattern. Heating is achieved with four radiant tube burners that have individual flame safety devices. The burner system incorporates a motorized control butterfly valve, and the gas flow is controlled by proportional ratio regulators. This design, with its baffle arrangement, delivers an even flow pattern, providing excellent temperature distribution and control in the furnace’s load chamber and high-efficiency heat recirculation (convection) horizontally across the aluminum castings. Excellent temperature uniformity was always considered an important parameter, and this has been shown to be ±5.4°F (±3°C) under full test in the provider’s manufacturing facility.
In order to maintain excellent thermal efficiency in operation, the furnace walls are fully lined using ultra large proprietary ceramic fiber modules. Their configuration and fixing provide for excellent insulation and long life coupled with low maintenance. The insulation layer is 6 in (150 mm) thick and has a density of 12 lb/ft3 (192 kg/m3).
The installation will see the drop-bottom furnace itself stationary — in a fixed elevated position — with the quench tank and loading car moving to accommodate baskets at the selected position. The furnace has a single, pneumatically operated horizontal slide door. For these particular aluminum castings, the company will employ a motorized water quench system provided by NUTEC Bickley, as well as its rails included leveling and installation. The tank has been designed to accept a full load of pieces within the work basket when the furnace is positioned vertically above it.
Press releases are available in their original form here.
A commercial heat treating company recently added new furnaces and process improvements to its operations in order to serve manufacturers in advanced industries, including aerospace and defense. The improvements include a high-temperature oxidation furnace, a fully rebuilt furnace, and the expansion of marquenching capabilities.
Phoenix Heat Treating, based in Phoenix, AZ, has introduced a high-temperature oxidation furnace specifically designed for space components. This equipment has a maximum operating temperature of 1975oF and operates in an air atmosphere, providing the thermal stability and precision needed for the demands of aerospace applications and to serve the evolving needs of the space industry.
A fully rebuilt furnace has been reactivated in the company’s production lineup. This furnace is tailored for processing primary long Inconel 718 and A286 age cycles. With a maximum weight capacity of 2000 lbs., it handles heavy and complex loads with a goal of ensuring consistent and reliable results for critical nickel-based alloy applications and improving efficiency and capacity by increasing the number of Inconel 718 cycles per week.
Marquenching operations are also seeing an upgrade as materials have been ordered to increase load sizes from 25 lbs. per load to 250 lbs. per load. Expected to be complete by mid-February, this enhancement represents a tenfold increase in capacity, allowing Phoenix Heat Treating to achieve faster turnaround times and larger batch processing capabilities.
Additionally, a state-of-the-art freeze/temper unit has been brought online. This equipment is capable of reaching temperatures between -270oF and 200oF and will be a part of the company’s aluminum thermal cycling processes, enabling precise control over temperature profiles for optimal material performance. The new unit’s capacity is roughly double that of the previous maximum reached and will allow Phoenix to handle significantly larger loads and meet growing customer demand.
The press release is available in its original form here.
A manufacturer which supplies agricultural ground engaging solutions has improved its production efficiency with two roller hearth furnace systems. The furnaces will be used to re-heat flat stock for hot forming, replacing existing equipment as part of a plant modernization initiative at its locations in both the United States and Canada.
The company commissioned the two 8000 lb/hr, high-temperature re-heat furnaces lines from CAN-ENG Furnaces International Limited (CAN-ENG) to heat steel plates to temperatures suitable for hotworking, where pieces are formed by a hydraulic press. The Ontario-based heat treating equipment provider designed the fully automated system to reduce energy consumption and floor space, while improving product flow and maintaining high-throughput requirements.
Scott Cummings Sales Manager CAN-ENG Furnaces International Limited
Each furnace is capable of operating up to 1750F and producing a part ready for forming every 15 seconds. The former equipment required alloy fixtures that consumed additional energy to heat up each time along with the product as well as costly periodic replacement and maintenance, heating the product directly on the furnace rolls increases the efficiency and reduces the overall equipment size.
“Can-Eng was selected as the supplier for this project based on our vast experience with high temperature roller hearth furnace systems and Can-Eng’s reputation to stand behind our equipment,” said Scott Cummings, sales manager for CAN-ENG.
The Michigan expansion of a furnace manufacturer and heat treating company has advanced with the erection of the entire steel structure in one week. The new 20,000-sq-ft building for Solar Atmospheres of Michigan Inc. will not only house additional vacuum and air furnaces but will also serve as a new shipping and receiving space.
Solar Atmospheres, headquartered in Souderton, PA, relocated equipment to its Michigan facility in April, 2024, where the ten vacuum furnaces are fully operational. The expansion project, which began in July, 2024, will more than double the company’s current footprint in Chesterfield, MI, and is on track for completion by the end of 2024.
The press release is available in its original form here.
Follow the development of this story in the previous Heat TreatToday posts found here, here, and here.
An aerospace company has purchased a rod overbend box furnace to heat treat parts under an inert atmosphere. The heat treating furnace has a maximum temperature rating of 2,000°F and a load capacity of 6,000 lbs.
The box furnace, which was manufactured and shipped by Michigan-based Lindberg/MPH, has an automated load transfer table and is designed to heat treat parts in a nitrogen atmosphere. A nitrogen gas flow meter controls the atmospheric conditions.
The box furnace includes an automated load transfer table. Under the table, five (5) fans with a variable-frequency drive provide accelerated cooling. The load table utilizes a pusher/puller mechanism to move parts trays in and out of the furnace.
The furnace’s radiant heating system uses heavy-gauge alloy rod over-bend heating elements mounted along the side walls and the floor. Two (2) Watlow F4T controllers control and record the furnace temperature, which allows for seven (7) zones of heating. The box furnace also meets Class 3 temperature uniformity of ±15°F at 1,000°F – 1,800°F.
The press release is available in its original form here.
Bill St. Thomas Business Development Manager Lindberg/MPH Source: Lindberg/MPH.com
A rod overbend box furnace with powered load/unload table is being shipped from Michigan to a manufacturer. An automated actuator increases safety measures protecting the operator.
Lindberg/MPH'sfurnace has a maximum temperature rating of 2,000°F and a load capacity of 900 lbs. The workspace dimensions of the furnace are 24” x 36” x 18” and is designed for air atmosphere applications. The box furnace features an automated actuator to flip the push/pull mechanism on the load table to eliminate the operators need to manually flip it into push position. This option allows the push/pull head to retract from the furnace once the work grid is in the furnace chamber and increases operator safety by removing the need to reach into the hot furnace with a hook to flip the push/pull head.
“This furnace design is a duplicate to a previous order . . . . with the [requested] modification of an automated actuator to provide easier loading for the operator," commented Bill St. Thomas, business development manager at Lindberg/MPH.
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Derek Dennis President Solar Atmospheres California
Solar Atmospheres of California (SCA) installed a new 14 foot long car bottom air furnace. With a maximum operating temperature of 1450°F, this furnace tempers large tool steel components, age hardens 15-5 PH, 17-4 PH, 13-8PH and nickel-based alloys, and anneals titanium forgings.
SCA is typically known around the world as a “vacuum only” heat treater. However, there is a great need for heat treating non finished parts and materials in accordance with the same specifications (AMS, MIL, Boeing, and Airbus) within different atmospheres where surface oxidation is permissible. This furnace allows for a “raw material” option.
“Solar Atmospheres of California is excited to be adding this new furnace and the added capability/capacity," stated Derek Dennis, president of SCA. The furnace has a working zone that is 60" square by 168" long with a total load capacity of up to 30,000 pounds.
Find heat treating products and services when you search on Heat Treat Buyers Guide.com
