Influence of Solution and Cryogenic Treatment on Microstructures and Mechanical Properties of High‐Strength Stainless Steel Before Aging

To optimize the microstructures of high strength stainless steel (HSSS) before aging, the influence of varying solution temperatures and a cryogenic treatment on the microstructures and mechanical properties of a HSSS are presented. The increase of solution temperatures from 950°C to 1050°C improved the Charpy U‐notch impact energy (CUN) of ST (solution treatment) and CT (solution + cryogenic treatment) specimens from 89 J and 86 J to 219 J and 206 J due to the more complete dissolution of carbides at higher solution temperatures; while the further rising solution temperature to 1100°C decreased the CUN of ST and CT specimens to 211J and 184J due to the coarsening of prior austenite and the hierarchical martensitic microstructures. The cryogenic treatment promoted almost all retained austenite (RA) in ST specimens transformed to be martensite, leading to the yield strength (YS) increased by 107–460 MPa. It is then proposed that the solution treatment of studied HSSS should ensure the complete dissolution of carbides but suppress the excessive growth of prior austenite; moreover, the cryogenic treatment after solution is necessarily required to remove coarse RA and greatly improve YS.