Research on the Regulation of Organization Performance and Heat Treatment Process of Low-Temperature Lightweight Steel

Abstract

Ni-system low-temperature steels have been widely used in the past 50 years, and the Ni-free low-temperature steels independently developed in China still have problems such as low yield strength, poor low-temperature toughness, and anisotropic properties. In this paper, based on the compositional design idea of ultra-low carbon, high manganese, and medium aluminum, a Fe-Mn-AI system lightweight cryogenic steel with high strength and good plasticity, as well as good low-temperature toughness, was developed. The regulation technology of the organization and properties of the experimental steel was mastered through the study of the heat deformation behavior as well as the heat treatment process, and the plastic deformation mechanism and the strong toughening mechanism of the experimental steel at room temperature and at one 1960C were revealed. Compared with Fe-Mn-Al austenitic steels, Fe-Mn-AI duplex steels exhibit a series of anomalous thermal deformation characteristics. During hot deformation, both work hardening and dynamic softening occur preferentially in 6 a ferrite. The dynamic restitution of ferrite in the early stage of hot deformation caused a yield-like behavior on the rheological curve. An intrinsic model of transient stresses in Fe-Mn-A1 duplex steels was developed. The model is empirically calculated to have a high prediction accuracy.