304 Stainless Steel Heat Treatment Process
Stainless steel stress relief annealing process: stress relief annealing is to eliminate the residual stress caused by plastic deformation processing, welding, and casting.
There is internal stress in the workpiece after forging, casting, welding and cutting. If it is not eliminated in time, it will deform the workpiece in the process of processing and use and affect the accuracy of the workpiece. It is very important to use stress-relieving annealing to eliminate the internal stress generated in the process of machining.
The heating temperature of stress relief annealing is lower than the phase transition temperature A1, so no microstructure transformation takes place during the whole heat treatment process. The internal stress is mainly eliminated by the workpiece in the process of heat preservation and slow cooling. In order to eliminate the internal stress of the workpiece more thoroughly, the heating temperature should be controlled during heating. Generally, it is fed into the furnace at low temperature and then heated to the specified temperature at a heating rate of about 100℃/h. The heating temperature of welding parts should be slightly higher than 600℃. The heat preservation time depends on the situation, usually 2~4h. The upper limit of the holding time of the casting stress relief annealing is taken, the cooling rate is controlled at (20~50)℃/h, and the air cooling can be produced only when the cooling is below 300℃.
