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Super-High-Strength and Formable Medium Mn Steel Manufactured by Warm Rolling Process

34 Pages Posted: 28 Mar 2019 Publication Status: Accepted

See all articles by Bin Hu

Bin Hu

University of Science and Technology Beijing - School of Metallurgical and Ecological Engineering

Bin Bin He

The University of Hong Kong - Department of Mechanical Engineering

Guan Ju Cheng

National Taiwan University - Department of Materials Science and Engineering

Hung Wei Yen

National Taiwan University - Department of Materials Science and Engineering

Hai Wen Luo

University of Science and Technology Beijing - School of Metallurgical and Ecological Engineering

Ming Xin Huang

The University of Hong Kong - Department of Mechanical Engineering

Abstract

In this paper, we demonstrate the design and manufacture of super-high strength medium Mn steel with good ductility, via the combination of warm rolling and V alloying. This new strategy produced not only the extensive precipitation of fine VC particles in both ferrite and austenite but also the bimodal size distribution of retained austenite (RA) grains. A substantial increase of yield strength up to 650 MPa was achieved after the intercritical annealing (IA) of this V-alloyed medium Mn steel without deteriorating ductility; whereas the calculated precipitation strengthening using the classical Ashby-Orowan theory is no more than 400 MPa. Quantifying possible strengthening mechanisms revealed that dislocation strengthening should make an additional contribution because recovery in austenite could be strongly retarded by the nanosized precipitates. In this V-alloyed steel, the coarse RA grains firstly transformed to martensite during yielding at the much higher stress threshold, followed by a significant work hardening during successive deformation due to dislocations multiplication, twinning-induced-plasticity (TWIP) and transformation-induced-plasticity (TRIP) in fine RA grains. The best achieved combination of tensile properties included 1.8 GPa ultimate tensile strength, 1.0 GPa yield strength and 18% total elongation.

Keywords: Medium Mn Steels, Recrystallization, Vanadium Carbides, Transformation Induced Plasticity, Twinning Induced Plasticity

Suggested Citation

Hu, Bin and He, Bin Bin and Cheng, Guan Ju and Yen, Hung Wei and Luo, Hai Wen and Huang, Ming Xin, Super-High-Strength and Formable Medium Mn Steel Manufactured by Warm Rolling Process (March 23, 2019). Available at SSRN: https://ssrn.com/abstract=3358845 or http://dx.doi.org/10.2139/ssrn.3358845

Bin Hu

University of Science and Technology Beijing - School of Metallurgical and Ecological Engineering

China

Bin Bin He

The University of Hong Kong - Department of Mechanical Engineering

China

Guan Ju Cheng

National Taiwan University - Department of Materials Science and Engineering

Taiwan

Hung Wei Yen

National Taiwan University - Department of Materials Science and Engineering

Taiwan

Hai Wen Luo (Contact Author)

University of Science and Technology Beijing - School of Metallurgical and Ecological Engineering ( email )

China

Ming Xin Huang

The University of Hong Kong - Department of Mechanical Engineering

China

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