Steel parts and components are used across many different industries including aerospace, automotive, heavy-duty equipment, agricultural equipment and even in the medical device and equipment manufacturing sector.
What is Stress in Metal?
Most parts and components made out of steel will go through some type of fabrication or manufacturing process. This can result in stress within the metal through the application of heat as well as with different types of machining and forming operations.
The most common causes of internal stress within steel parts include cold working, thermal cutting, welding, hot rolling, grinding and in quenching. The result is a change in the internal structure at a granular level, which can lead to increased risk of stress-related failures, twisting or buckling of the part and stress corrosion cracking.
Through the processes used for stress relieving steel, this internal granular change can be reversed. The process is never 100% completed through stress relieving methods, but it will allow for reformation of the internal structure to avoid the problems mentioned above.
Thermal Stress Relief
The theory behind stress relieving steel through the application of heat and slow cooling allows for the realignment of the interior gains in the metal. The heat actually weakens the bonds, allowing for both changes in the properties of the metal as well as the granular alignment.
This process has to be carefully controlled. The metal must be heated to a point lower than the austenitic transformation for the specific steel or alloy. This temperature is then maintained for a specific period of time.
The cooling process is equally important in stress relieving steel. Cooling must be done uniformly as well as over time to create the desired stress relief as well as maintained the desired changes in the physical property of the part or component.
