Mechanical behavior and microstructural evolution of a modified CSS-42L steel during tempering
摘要
The rapid development in the aerospace industry requires the service performance of high-strength and heat-resistant bearing steel, especially in terms of strength and ductility synergy. A modified CSS-42L steel was obtained by multicomponent modulation, and an exceptional strength and ductility synergy of the alloy was attained through the adjusted tempering treatment. The tensile strength of 1986 MPa, the yield strength of 1622 MPa, and the uniform elongation of more than 17% were attained in the specimen tempered at 540 °C, being superior to the mechanical properties of many previously reported alloys. Such superior performance originates from the generation of the high-density intermetallic compound Laves-Fe2Mo, the reduction of the larger M6C phase, and the formation of film-like reverse austenite. As a result, the strong interaction between the high-density dislocations of the matrix and the nanoprecipitates dominates the deformation microstructures of the specimen, strengthening the alloy. Meanwhile, the reverse austenite effectively inhibits premature crack initiation and localized stresses, increasing the uniform elongation.