Stainless steel is one of the most commonly used materials in the manufacturing of parts and components across a wide range of industries. The corrosion, resistance and the strength of stainless steel make it a natural match for many different applications. It is also an alloy that is prone to becoming brittle when worked, so annealing treatments are required to report the workability of the part or component after manufacturing.
Often, during processing, stainless steel is changed on a physical and molecular level. Through the use of annealing heat treatment specific changes can be made to the metal to create desired benefits over the natural state. By maintaining a specific temperature for a specific time, the various alloys will have different characteristics enhanced based on their end-use requirements.
A Step-by-Step Process
With any annealing heat treatment, the desired effects or changes in the stainless steel are developed over several steps or stages in the process. Each of these stages has to be carefully controlled with regards to heat, time and other factors to ensure the correct internal change in the metal.
Each of the stages also provides a specific aspect in the annealing heat treatment. Heating is the first step, and it used to change or alter the physical, granular structure of the stainless steel. All irregular granular boundaries or structures are removed, providing a more consistent structure.
The process of heating is followed by cooling, typically through air cooling, that allows the internal structure to recrystallize. The natural grain will be solidified in the stainless, free from any defects that were created from working of the alloy.
In some applications, and for different types of metals and alloys, this combination of heating and cooling during the annealing treatment may be repeated. However, the key will always be to control the heating and the cooling process with regards to temperature and time to obtain the desired final results.