Cryogenic Mechanical Properties of a Novel High-Strength and High-Toughness Steel: Constitutive Models and Microstructure

Abstract

This work aims to study the constitutive models and microstructure of a novel high-strength and high-toughness (HSHT) steel under cryogenic temperature. A series of cryogenic tensile tests were conducted using a testing machine equipped with a cryogenic chamber. The results showed that the HSHT steel exhibits an obvious temperature-dependence effect. As the temperature decreased, the yield strength and tensile strength gradually increased, while the uniform elongation first increasing and then decreasing. At a cryogenic temperature of -196°C, the HSHT steel exhibited significantly enhanced mechanical properties. Specifically, the yield strength, tensile strength, and uniform elongation were 1200 MPa, 1620 MPa, and 30% respectively. Based on the obtained temperature-dependence effect, the classic Ludwigsonconstitutive model that all parameters were functions related to temperature was developed and its accuracy was verified through numerical analysis. Furthermore, the microstructure of HSHT steel was investigated during the different deformation stage through microstructure characterization techniques. High dislocations density, denser mechanical twins and slight phase transformation were occurred when deformation at -196°C. These findings reveal the relationship between mechanical behavior and deformation mechanisms in HSHT steel within the low-temperature regime, providing valuable insights for the design of HSHT steel in cryogenic applications.

Keywords: High-strength and high-toughness steel, Cryogenic temperature, Mechanical properties, constitutive model, microstructure