Under Pressure? Here’s a Stress Relief Round Up

December 4, 2024 / Manufacturing Heat Treat Technical Content, STRESS RELIEVING TECHNICAL CONTENT

Did you know that November 6 was National Stress Awareness Day? It seems an appropriate designation to cover the days and weeks that follow Election Day as well as those leading up to the holidays. For many who are well aware of the stress of the events of the season, Heat Treat Today wants to help with a different kind of stress relief.

Today we’re highlighting technical content that we’ve published over the last couple of years about stress relieving processes. Read an overview about stress relieving stainless steel components, listen to a Lunch & Learn dialogue about this underrated process, and explore a mechanical testing method for measuring material strength.

Stainless Corrosion

It is critical to provide things like stainless steel appliances and the Tesla truck with proper maintenance to keep the corrosion resistance and appearance lasting as long as possible.

Stainless steel shines in our kitchens and is becoming more popular in auto showrooms, mostly because of the promise that it is corrosion resistant. What most people don’t realize is that stainless steel will rust in a lot of circumstances. Sarah Jordan explores how stainless steel can be compromised by improper heat treatment and the steps heat treaters can take to prevent corrosion:

“Improper heat treating can also contribute to stress corrosion cracking. When material is quenched, it can cause residual stresses that, if not relieved, can become an issue.

“Corrosion in stainless steel can often be traced to improper heat treatment. When stainless steel is heated between 842–1562°F (450–850°C), chromium carbides can form at the grain boundaries, depleting the surrounding areas of chromium and making them susceptible to corrosion.”

To read the article in full, click here.

Heat Treat Radio #88: Lunch & Learn — 3 Most Underrated Processes

Click on the image to hear this episode of Heat Treat Radio and read the transcript.

In this Lunch & Learn episode from Heat Treat Radio, Dave Mouilleseaux discusses the three most underrated heat treat processes, including stress relieving manufactured components. If a comprehensive analysis of a heat treat operation needs to be performed on a manufactured component, such as a gear or a shaft, it is necessary to take into consideration any prior existing stresses in the part and what effect that has on the part.

The detrimental effects of not having stress relieved
Source: pixabay

“Many times during the course of my career, I’ve had a customer come to me and say, ‘The part I gave you was correct, and you’ve given it back to me and then fill-in-the-blank. It’s warped, it’s changed size, it’s shrunk, all of those things.’

“What have you done in your heat treating process?” asked Mouilleseaux. “You have to back up all the way to the beginning of how this part was manufactured and deal with all of those component steps in order to answer that question properly. Stress relieving is one of the answers. It’s not the answer. It’s not the only answer, but it is one of them that has to be considered.”

To listen to this episode of Lunch & Learn, click here.

Indentation Plastometry

Photograph of the Hardox steel samples, with and without the WC insert attached, showing high levels of oxidation following from the brazing process.
Source: Plastometrex

Mechanical testing is a standard production step in heat treating operations, but conventional methods of testing don’t always yield stress values consistent with the testing calculations.

Indentation plastometry allows users to obtain material strength characteristics in a way that is faster, cheaper, and simpler than conventional mechanical testing procedures. James Dean explores this novel mechanical testing method developed to infuse efficiency and accuracy into the process.

“The testing process is fully automated and involves three simple steps. The first is the creation of an indent using the indentation plastometer which is a custom-built, macromechanical test machine. The second is measurement of the residual profile shape using an integrated stylus profilometer.

“The third is the analysis of the profile shape in a proprietary software package called SEMPID, which converts the indentation test data into stress-strain curves that are comparable to those that would be measured using conventional mechanical testing methods. The entire procedure takes just a few minutes, and the surface preparation requirements are minimal.”

To read this article in full, click here.

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Under Pressure? Here’s a Stress Relief Round Up Read More »

Stress Relieving Tips From Heat Treat Today

Stress relieving tips from Heat Treat Today? It's not what you think! In this Technical Tuesday, we'll be sharing some fast facts you need to know about stress relieving. It may not be as relaxing as some guided meditation, but at least you will walk away with a refreshed knowledge of stress relieving, a new technology for measuring material stress, and a video demonstration of the stress/strain curve.

Stress Relieving Fast Facts

What is stress relieving? In the most basic sense, stress relieving is heating a metal to a relatively low
Dan Herring
"The Heat Treat Doctor"
The HERRING GROUP, Inc.

temperature and then slowly cooling it to reduce the affect of manufacturing-induced stresses.
Why do heat treated parts need to be stress relieved? Manufacturing processes (forging, shearing, bending, etc.) introduce internal stresses, and these stresses, if left unaddressed, can cause the finished part to fail in its end application.
Thermal stress relieving is the preferred method of stress relieving, but mechanical stress relieving is also an option. Vibratory stress relieving and shot peening are two mechanical stress relieving methods available to heat treaters.

Want more fast facts? Check out Dan Herring, The Heat Treat Doctor's^®, Atmosphere Heat Treatment, Volume 1.

Addressing Stresses: Indentation Plastometry

Stresses introduced during the heat treating process must be addressed. Failing to address these stresses can be disastrous. Mechanical testing systems are crucial in ensuring heat treating had its desired effect and that no new stresses have been introduced to the material. As most heat treaters know, the stress/strain curve of materials is often a give and take. To get high strength, you often have to give up ductility. Measuring the extent of these trade-offs — and measuring plasticity and strength characteristics in general — after heat treating can be time consuming.

In this episode of Heat Treat Radio, James Dean of Plastometrex explains a new technology, indentation plastometry, that measures microscopic stresses in heat treated material. These stresses can affect the yield point of a material and the point of plastic deformation. What's even better is that, with indentation plastometry, heat treaters can view stress/strain curves in minutes and know if there is a need for further stress relieving.

A Refresher on the Stress/Strain Curve

Need a refresher on the stress/strain curve after hearing from James Dean? Check out this episode of Heat Treat TV.

The stress/strain curve is "metallurgy basics." If you spend any amount of time in the heat treating world, this graph will be a familiar sight to you. Basic though it may be, a refresher it always a good idea. Just how much stress can a material withstand before breaking? How does heat treating affect the yield point of different materials?

plastometry