A new 1.2 GPa ultra-high strength AISI 316L steel designed by uniform microstructure and texture

Abstract

In this study, to achieve a uniform microstructure and texture and high strength in AISI 316 L austenitic stainless steel (ASS), asymmetric turned rolling (ATR) was employed. The effect of cold rolling strain (10 %, 30 %, 50 %, and 70 %) on the microstructure and mechanical properties of AISI 316 L ASS was investigated. With increasing the thickness reduction, the fraction of deformation twins, strain-induced martensite (SIM), and shear bands was increased. The texture results showed that the shear textures (Rotated Cube component and γ-fiber) with the same intensity as in the surface areas were also formed in the mid-thickness of the sheet due to the uniform strain distribution throughout the sheet induced by the ATR process. With increasing the rolling strain, hardness and strength were increased, and ductility and toughness were decreased due to the strain-hardening mechanism and increase in the density of deformation twins, SIMs, and shear bands. The AISI 316 L sheet after 70 % ATR process exhibited hardness of 396 HV, yield strength of 1176 MPa, tensile strength of 1186 MPa, ductility of 8.6 %, and toughness of 166 J/cm³. The fracture mode was ductile, however, by increasing the rolling strain up to 50 %, the depth and size of dimples were decreased.