The Effect of Friction-Stir Welding in Hydrogen Embrittlement of Fe-17Mn Alloy

Abstract

In present study, we suggest the friction stir welding (FSW) is an effective welding technique for improving the resistance of hydrogen (H) embrittlement in Fe-17Mn (wt.%) alloy with a dual phase of γ austenite and ε martensite. The FSW specimen exhibited the enhanced resistance of H embrittlement during H-charging/tensile deformation despite active α′ martensitic transformation which is apt to H embrittlement, relative to base metal. During H-charging, numerous ε phase and higher initial dislocation density, as potential sites for H trapping, after FSW reduced H diffusion into specimen, causing the shallow H-related brittle fracture. In addition, the increased γ/ε interface/boundary in the FSW specimen alleviated H accumulation. During tensile deformation, the grain rotation and higher c^ε/a^ε ratio by FSW reduced Schmid factor of finer grains, leading to stronger resistance of boundary decohesion and the suppression of H-induced crack growth.

Keywords: Hydrogen embrittlement, Friction stir welding, Fe-high Mn alloys, Transformation-induced plasticity