Discontinuous transformation-induced plasticity behaviour in governing the mechanical behaviour in medium-Mn steels

ABSTRACT

Here, we address the continuing challenges and scientific gaps in obtaining high strength and high elongation in medium-Mn steels. Electron microscopy and X-ray diffraction studies clearly underscored that the discontinuous transformation-induced plasticity played a determining role in impacting high strength–toughness combination in conjunction with the microstructural constituents. The discontinuous TRIP effect during deformation involved stress relaxation, which was responsible for high ductility. An excellent combination of a high tensile strength in the range of 1238–1502 MPa and a total elongation of 25–33.6% was obtained when the steels were subjected to an intercritical hardening in the temperature range of 600–750°C and low tempering at 200°C. The intercritical hardening influenced the co-existence of austenite, ferrite and martensite in a manner such that the deformation behaviour varies with the Mn-content.

KEYWORDS:

• microstructural evolution
• superior mechanical properties
• heat treatment
• deformation behaviour
• discontinuous transformation during deformation

Acknowledgments

This research was funded by the National Natural Science Foundation of China, grant number 52005304, Science and Technology Plan for Youth Innovation Team in Colleges and Universities of Shandong Province (2022KJ219), the National Natural Science Foundation of China (52175342), the Natural Science Foundation of Shandong (ZR2021ME129). I sincerely thank my former advisor at the University of Texas at El Paso for the review of the study presented here.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also form part of an ongoing study.

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [52005304]; National Natural Science Foundation of China [52175342]; Science and Technology Plan for Youth Innovation Team in Colleges and Universities of Shandong Province [2022KJ219]; Natural Science Foundation of Shandong [ZR2021ME129].