Design of an effective heat treatment involving intercritical hardening for high-strength–high elongation of 0.2C–1.5Al–(6–8.5)Mn-Fe TRIP steels: microstructural evolution and deformation behaviour

ABSTRACT

We propose an effective heat treatment involving a combination of intercritical hardening and tempering to obtain high strength–high ductility in hot-rolled 0.2C–1.5Al–(6–8.5)Mn–Fe transformation-induced plasticity (TRIP) steels. An excellent combination of high ultimate tensile strength of 1045–1380 MPa and total elongation of 34–39% was obtained when the steels were subjected to intercritical hardening at 630–650 °C and tempered at 200 °C. Intercritical hardening impacted the co-existence of austenite, ferrite and martensite, such that the deformation behaviour varied with the Mn content. The excellent properties of the steels were attributed to cumulative contribution of enhanced TRIP effect of austenite and ferrite and martensite constituents. The discontinuous TRIP effect during tensile deformation involves stress relaxation and led to consequent enhancement of ductility.

KEYWORDS:

• Microstructural evolution
• superior mechanical properties
• heat treatment
• deformation behaviour
• discontinuous TRIP effect

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

The present study was financially supported by the National Natural Science Foundation of China: [grant number 51974084]; Natural Science Foundation of Shandong Province: [grant number ZR2019BEE034]; Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents: [grant number 2017RCJJ017]; Shandong Province Key Laboratory of Mine Mechanical Engineering,China: [grant number 2019KLMM104]; Natural Science Foundation of Shandong Province: [grant number 2019GGX104009].