Microstructure Evolution and Recrystallization Temperature Change of Cold-Rolled Fe–19Mn–0.6C Twinning-Induced Plasticity Steel during Annealing

Hui Xue,Kai Guo,Zhijia Zhang,Mengmeng Zhang,Hui Yuan

doi:10.3390/met11081181

Abstract

Ultra-high twinning-induced plasticity (TWIP) steel is receiving increasing attention in the automobile industry. Self-designed Fe–19Mn–0.6C TWIP steel was subjected to reveal the relationship between microstructures, which were related to recrystallization starting/ending temperature and cold rolling. The results indicated that initial deformation twins, secondary deformation twins, and nano-twins were successively generated in rolled TWIP steel with the increase of cold rolling, deformation twins, and dislocations, as well as with the elongation of grains. The elements remained uniformly dispersed rather than agglomerated in the twin crystals and grain boundaries. The recrystallization starting temperature changes of TWIP steel were 500–525, 400–425, 400–415, and 400–410 °C at cold rolling deformations of 25%, 50%, 75%, and 88%, respectively. Furthermore, the obtained corresponding recrystallization ending temperature changes were 580–600, 530–550, 520–540, and 500–520 °C, respectively. The linear relationship between cold deformation and hardness suggests that cold rolling can increase dislocation density and thus facilitate improving the hardness of TWIP steel.

Highlights

The development of lightweight body materials is geared toward saving energy, reducing emissions, and improving the safety of the modern automobile [1,2,3]
The strain-hardening and twin formation of Fe–22Mn–0.6C and Fe–22Mn–0.6C–1.5Al Twinning-induced plasticity (TWIP) steels during tensile were compared by Zhang et al [14]
The Fe–19Mn–0.6C TWIP steel, with its chemical composition listed in Table 1, was melted in a 50 kg vacuum induction furnace and refined via electromagnetic stirring

Summary

Introduction

The development of lightweight body materials is geared toward saving energy, reducing emissions, and improving the safety of the modern automobile [1,2,3]. The research of TWIP steels has been focused on mechanical property characterizations [5,6,7], deformation microstructure evolution, and microstructure transformation during cold rolling and tensile testing [8,9,10,11]. The deformed microstructure exhibits a typical plane slip, dislocations accumulation, and mechanical twins. The microstructure evolution and strengthening mechanism of Fe–23Mn–0.3C–1.5Al steel during cold rolling were studied by Kusakin et al [13]. The strain-hardening and twin formation of Fe–22Mn–0.6C and Fe–22Mn–0.6C–1.5Al TWIP steels during tensile were compared by Zhang et al [14]. Deformation twins, especially secondary deformation twins, play a key role in preventing the dislocation slip in Fe–22Mn–0.6C steel rather than that in Fe–22Mn–0.6C–1.5Al steel

Results

Discussion

Conclusion