Tailoring reversed austenite and carbide precipitation via tempering to achieve superior impact toughness in high chromium martensitic steels
摘要
The influence of tempering temperatures (200, 350, and 500 °C) on the microstructure and mechanical properties of high chromium (Cr) martensitic steel is investigated. The evolution of microstructure and mechanical properties of the heat-treated steels was thoroughly analyzed. The tempering temperature emerged as a key factor influencing the morphology of martensitic laths and the precipitation of carbides, specifically Cr23C6 and Fe3C. Variations in austenite content, essential for enhancing impact toughness and ductility, were observed at different tempering temperatures. Tempered steels showed reductions in Rockwell hardness and tensile strength, along with an increase in yield strength relative to the as-quenched state. The impact toughness was significantly affected by tempering, with impact energy reaching 337 J at 350 °C. Significantly, tempering at 350 °C improved elongation to 10.0%, thus indicating the enhanced ductility. The exceptional toughness and ductility observed with tempering at 350 °C are attributed to the intentional formation of reversed austenite, a pivotal finding that provides critical insights into optimizing the tempering process for high-performance high chromium martensitic steels.