Strain rate dependency of hydrogen embrittlement resistance in an additively manufactured equiatomic CoCrFeNi high-entropy alloy

The present study aims at understanding the influence of additively manufactured material microstructure, of CoCrFeNi high entropy alloy fabricated by Laser Powder Bed Fusion (LPBF), on its hydrogen embrittlement characteristics. To have a comprehensive understanding of the phenomenon, tests were carried out at different strain rates and also for conventionally manufactured alloy. LPBF alloy was found to have less resistance to hydrogen embrittlement, and there was considerable reduction in ductility in the presence of hydrogen, at slow strain rate test condition. Hydrogen - material microstructure interaction, inherent defects and dislocation density were found to be the major factors that govern hydrogen embrittlement resistance of LPBF alloy. • LPBF microstructure strongly influences hydrogen embrittlement (HE) resistance. • HE susceptibility in LPBF alloy increases significantly at lower strain rates. • Porosity, twins, and dislocation density assist in crack initiation under hydrogen. • Stress and hydrogen segregation at boundaries promote hydrogen-assisted cracking.