Effect of thermomechanical treatment on microstru cture and mechanical properties of AISI 301LN stainless steel

摘要

A wide range of cold thickness reduction (10-80%) and subsequent annealing were carried out on AISI 301 LN stainless steel. X-rays and Feritscope MP30 were used to identify the strain induced α'-martensite phase and its volume fraction respectively. The microstructure was observed by optical micrograph and scanning electron microscope. The results show that shear bands were present and strain induced a'-martensite nucleated at their intersections. The volume fraction of a'-martensite increased with the increased cold reduction by the continuous growth of embryos, which resulted in the increasing yield and tensile strength. The reversion of a'-martensite to austenite occurred after subsequent annealing. The grain size variation of austenite was related to the annealing regime. A good combination of strength and ductility can be obtained after annealing at 650°C for 30 min. The effect of grain size on yield strength conformed with the Hall-Petch relationship in the entire range of our analysis.