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Open AccessArticle

Microstructure-Tensile Properties Relationship and Austenite Stability of a Nb-Mo Micro-Alloyed Medium-Mn TRIP Steel

1
The State Key Laboratory of Refractories and Metallurgy, Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, China
2
Wuhan Bao Steel Central Research Institute, Wuhan 430083, China
*
Author to whom correspondence should be addressed.
Metals 2018, 8(8), 615; https://doi.org/10.3390/met8080615
Received: 25 June 2018 / Revised: 28 July 2018 / Accepted: 2 August 2018 / Published: 6 August 2018
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Abstract

This study investigated the microstructure–tensile properties relationship and the retained austenite room temperature stability of a Nb and Mo micro-alloyed medium manganese transformation induced plasticity (TRIP) steel. A number of findings were obtained. Most importantly, the steel after being processed by quenching and tempering (Q & T) exhibited excellent tensile properties, i.e., the strength of 878–1373 MPa, the ductility of 18–40% Mo, and Nb microalloying served to control the fraction of retained austenite and to improve tensile strength by fine grain strengthening. Excellent tensile properties were attributable to the large amount of retained austenite which produced a discontinuous TRIP effect. This effect led to the production a large amount of martensite which relieved the stress concentration, contributing to the coordinated deformation between the phases and thus improving the deformability of the steel. Additionally, the differences in Mn and C contents led to varying degrees of austenite stability and the length of the Lüders band decreased as the intercritical annealing temperature increased. The micro-alloyed medium manganese steel experimented on our study showed considerable improvement in tensile properties in comparison with the 5Mn-0.1C medium manganese steel in previous studies. View Full-Text
Keywords: medium Mn steel; (Nb; Mo)micro-alloyed; tensile properties; TRIP effect; austenite stability medium Mn steel; (Nb; Mo)micro-alloyed; tensile properties; TRIP effect; austenite stability
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Liu, C.; Peng, Q.; Xue, Z.; Deng, M.; Wang, S.; Yang, C. Microstructure-Tensile Properties Relationship and Austenite Stability of a Nb-Mo Micro-Alloyed Medium-Mn TRIP Steel. Metals 2018, 8, 615.

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