Design of Heterogeneous Lamella Microstructure of 316L Austenitic Stainless Steel and Effect of Aging on Its Mechanical Behavior and Corrosion Properties

Abstract

316L austenitic stainless steel (ASS) with a heterogeneous structure exhibits favorable mechanical properties at room temperature, promising excellent application potential. However, the thermal stability of 316L ASS with heterogeneous lamella structure (HLS) has not been adequately addressed yet. Herein, an HLS of 316L ASS is fabricated through 78% cold rolling followed by annealing at 750 °C for 13 min. The detailed investigation focuses on the influence of microstructure evolution on the mechanical properties and corrosion resistance of the alloy after aging at temperatures ranging from 350 to 550 °C for 100 h. The results show that a notable quantity of residual martensite persists even after annealing at high temperatures for a brief duration. The dislocation density of the test steel is reduced after long‐term aging treatment, and the residual martensite is further reversed into austenite during aging. In addition, the aging treatment also promotes further growth of nanocrystalline/ultrafine‐grained, which weakens the heterogeneous characteristics of HLS 316L ASS, resulting in a slight decrease in mechanical properties. However, the decrease in defect density and the enhancement of recrystallization degree are beneficial for eliminating most of the corrosion‐sensitive areas in the cold‐deformed structure, thereby improving the corrosion resistance.