Liquid metal embrittlement in laser lap joining of TWIP and medium-manganese TRIP steel: The role of stress and grain boundaries
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Date
2018-11-01
Authors
Razmpoosh, Mohammad Hadi
Biro, Elliot
Chen, Daolun L.
Goodwin, Frank
Zhou, Yang-Tao
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
High-Manganese austenite-containing steels with superior combination of strength and ductility have shown potential for enhancement of passenger safety and body-in-white (BIW) weight reduction. Even though Zn-coated austenitic steels have improved corrosion resistance, they are highly susceptible to liquid metal embrittlement (LME) during welding. The present work is aimed to address LME susceptibility during restrained laser lap joining of high-Mn twinning induced plasticity (TWIP) and medium-Mn transformation induced plasticity (MMn-TRIP) steels. Electron probe micro-analysis (EPMA) results showed that stress-assisted diffusion of Zn into the austenite grain boundaries and further liquid Zn formation by a peritectic reaction lead to grain boundary decohesion. Electron backscatter diffraction (EBSD) results demonstrated that high angle and special grain boundaries are prone to Zn-penetration within the heat-affected-zone (HAZ). Additionally, LME sensitivity was observed to be highly dependent on the magnitude of applied stress.
Description
The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.matchar.2018.09.018 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/
Keywords
Microstructure, Fiber laser welding, Liquid metal embrittlement (LME), Transformation induced plasticity steel, Twinning induced plasticity steel