effect of cold-rolling and annealing treatments on the microstructure and mechanical properties of aisi 309s austenitic stainless steel

Microstructural evolutions and mechanical properties of a cold-rolled 309s austenitic stainless steel were investigated after reversion annealing in the temperature ranges of 700-1000°c for 3- 20 min. the specimen was first cold-rolled at room temperature to 90% thickness reduction. the microstructure was analyzed by optical and sem methods and the mechanical behavior was studied by tensile tests and hardness measurement. the results depicted that negligible straininduced ά-martensite was formed after cold-rolling. in addition, elongated austenite grains were observed after deformation followed by annealing below 700°c which was a signature of the recovery process. the recrystallization of the deformed austenite was dominant above 800°c, while recrystallization followed by grain growth were seen at 900°c. moreover, the significant grain growth was observed at 1000°c. the optimum annealing temperature and time for achievement of a uniform recrystallized grain were at 800°c for 3 min which resulted in considerable grain refinement. the grain refinement led to improvement of mechanical properties of investigated austenitic stainless steel. the hardness value of refined austenite grains was 195% greater than that of the as-received steel. finally, current work can shed some light on the effect of grain refinement on the control of microstructural and mechanical property of austenitic stainless steels.