Softening interstage annealing of austenitic stainless steel sheets for stamping processes

To study the mechanics of work-hardening and annealing-softening, a series of experiments were conducted on samples of 304 austenitic stainless steel sheets. In addition, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, and tensile testing were carried out to study changes and mechanisms of the stainless steel structures and properties during work-hardening and annealing-softening. The results indicate that annealing at low temperatures （100-500 ~C） can only remove partial residual stresses in the sample and the softening via annealing is not obvious. Bright annealing and rapid cooling in a protective atmosphere can completely soften the cold-worked material. In addition, the low-temperature sample without a protective atmosphere only has a little oxidation on the surface, but at higher temperature the oxidized layer is very thick. Thus, high-temperature annealing should include bright annealing.