Strong and ductile medium-Mn steel achieved via controlled martensite tempering

Abstract

The present work simplifies the previous room-temperature quenching and partitioning (RT Q&P) process down to a single furnace cooling process, delivering a medium Mn steel with an ultimate tensile strength (UTS) of 1.7 GPa and a uniform elongation of 9.5%. The martensite tempering during furnace cooling is featured with slightly reduced dislocation density and is free of cementite precipitation, which is beneficial for ultrahigh UTS. Although the carbon partitioning is limited, the banded large austenite grains have proper mechanical stability owing to pre-existing high carbon content and the strong martensite matrix, allowing the gradual transformation-induced plasticity (TRIP) effect to enhance the work hardening behaviour and thus the good uniform elongation.

KEYWORDS:

• Martensite
• controlled tempering
• dislocation recovery
• medium-Mn steel

Acknowledgements

B.B. He gratefully acknowledges the financial support from the National Natural Science Foundation of China (grant number U52071173), Science and Technology Innovation Commission of Shenzhen (Project No. JCYJ20210324120209026; KQTD2019092917250571), and Major Talent Programs of Guangdong Province (Contract No. 2019QN01C435). The authors would like to acknowledge the technical support from SUSTech Core Research Facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statements

The datasets generated during and/or analysed during the current study are available from the corresponding author upon reasonable request.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant number U52071173].