Cyclic deformation behavior and microstructure evolution of high-carbon nano-bainitic steel at different tempering temperatures

摘要

Bainitic steel is applied in many cyclic loading projects due to its excellent comprehensive mechanical properties. In this study, the cyclic hardening/softening behavior and microstructure evolution of high-carbon nano-bainitic steel were investigated to analyze the cyclic deformation mechanism. Results showed that the optimal tempering temperature was determined to be at low temperature. During cyclic deformation, the retained austenite is transformed into martensite according to the Kurdjumov-Sachs (K-S) and Nishiyama-Wassermann (N-W) orientation relationships, and deformation twins are generated in the retained austenite. The cyclic deformation of high-carbon steels at a total strain amplitude of 0.6% manifests no obvious cyclic softening behavior after low-temperature tempering, mainly due to the high density of dislocation tangle around martensite and deformation twins induced by cyclic deformation.