Influence of Laser-Welding on Microstructure and Corrosion Properties of Twinning-Induced Plasticity (TWIP) Steel.

Chengcheng Xu,Ying Jin,Lei Wen,Youkang Zhang,Dongbai Sun,Wanlei Liu

doi:10.3390/ma13194315

Abstract

The effect of welding speed on microstructure, mechanical properties, and corrosion properties of laser-assisted welded joints of a twinning-induced plasticity (TWIP) steel was investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) analysis, electrochemical test, and micro-area scanning Kelvin probe test (SKP). The results reveal that the welded joints, with a fully austenitic structure, are obtained by laser welding. In addition, the preferred orientation of grains in fusion zone (FZ) increased with the increase of welding speed. Additionally, the coincidence site lattice (CSL) grain boundaries of FZ decreased with increasing welding speed. However, potentiodynamic polarization and SKP results demonstrated that the welding speed of 1.5 m/min renders superior corrosion resistance. It can also be inferred that the corrosion properties of the welded joints are related to the grain size and frequency of CSL grain boundary in FZ.

Highlights

The effect of twinning-induced plasticity (TWIP) has been developed to fabricate advanced high-strength steel, where mechanical deformation is introduced to produce twins
The potentiodynamic polarization measurements were carried out after immersion for an hour, while the fluctuations of open-circuit potential (OCP) were less than 5 mv in 10 min
The scanning started of heat affected zone (HAZ) and fusion zone (FZ) was the same as base metal (BM)

Summary

Introduction

The effect of twinning-induced plasticity (TWIP) has been developed to fabricate advanced high-strength steel, where mechanical deformation is introduced to produce twins. The combination of high strength, high plasticity, and high strain hardening makes TWIP steel an ideal candidate for automobiles [1,2,3,4,5,6]. The research on laser welding of TWIP steel has mainly focused on the structure and mechanical properties of welded joints under welding process [10,11,12]. The microstructure and mechanical properties, i.e., strain rate [13], strain hardening behavior [14], fatigue fracture [15], temperature and stacking fault energy [16,17], and crystallographic behavior [18], of high-manganese

Methods

Results

Conclusion