Austenite Stability and Deformation Behavior in Medium Mn Steel Processed by Cyclic Quenching ART Heat Treatment.

Chunquan Liu,Yuxin Cao,Guanni Liu,Yong Wang,Fen Xiong,Zhengliang Xue,Qichun Peng

doi:10.3390/ma14237132

Chunquan Liu, Yuxin Cao + Show 5 more

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https://doi.org/10.3390/ma14237132

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Abstract

This study investigated the austenite stability and deformation behavior of cyclic quenching-austenite reverse transformation processed Fe-0.25C-3.98Mn-1.22Al-0.20Si-0.19Mo-0.03Nb medium Mn steel. A number of findings were obtained. Most importantly, the extent of the TRIP effect was mainly determined by an appropriately retained austenite stability rather than its content. Simultaneously, chemical elements were the key factors affecting austenite stability, of which Mn had the greatest impact, while the difference of retained austenite grain size and Mn content resulted in different degrees of retained austenite stability. Additionally, there were still large amounts of strip and granular-retained austenite shown in the microstructure of the CQ3-ART sample after tensile fracture, revealing that the excessively stable, retained austenite inhibited the generation of an extensive TRIP effect.

Highlights

Lightweight automobiles are an effective means to reduce energy consumption and environmental pollution [1,2,3]
The purpose of this study was to lay a scientific foundation for obtaining excellent comprehensive performance in Nb-Mo medium Mn steel by the cyclic quenching-austenite reverse transformation (CQ-ART) process on the basis of our previous research [16]
The rods were cold-rolled to 3.8 mm thick strips, air-cooled to ambient temperature, and the as-hot-rolled strips were cold-rolled to 1.9 mm in thickness

Summary

Introduction

Lightweight automobiles are an effective means to reduce energy consumption and environmental pollution [1,2,3]. Advanced high-strength steel, especially advanced highstrength medium manganese steel for third-generation automobiles, is currently the most promising lightweight automotive material [4,5]. Research on the strength-ductility mechanism of automotive steel has shown that it effectively and simultaneously improves the strength and plasticity of automotive steel by using phase-transformation-induced plasticity [6,7,8]. Metastable retained austenite deforms under the action of an external load, and induces the formation of martensitic transformation, thereby improving the material strength. The strain-induced transformation from austenite to martensite produces stress relaxation, which delays the occurrence of material necking and increases the strength and plasticity of the material [11,12]

Objectives

Methods