Embrittlement behaviour of metal additive-manufactured high-entropy alloy components under gaseous and electrochemical hydrogen charging

Embrittlement is an environmentally induced fracture that primarily affects metallic materials. This phenomenon occurs when hydrogen is absorbed on the metal surface and penetrates to the core, followed by degrading the mechanical properties in a hydrogen-rich environment. This reduction in mechanical properties results in a loss of ductility and toughness in materials, thereby increasing their susceptibility to cracking caused by hydrogen. Embrittlement can be introduced into materials through various means. This work mainly focuses on embrittlement failure that occurs under hydrogen-inducing conditions. Gaseous and electrochemical hydrogen charging exposure are related to this study. Mitigating hydrogen embrittlement involves controlling two aspects: adding alloying elements and treating the metal surface. This work examines the addition of alloying elements to reduce metals' susceptibility to hydrogen uptake, utilising an advanced fabrication method known as metal additive manufacturing in conjunction with high-entropy alloy concepts. Mechanical properties such as tensile strength and fatigue demonstrate the deterioration of hydrogen embrittlement behaviour in structural components, leading to unforeseen catastrophic failures. This work summarizes (i) the hydrogen effects on material performance, (ii) additively manufactured high entropy alloy (HEAs) and the factors influencing embrittlement, (iii) methods of hydrogen charging, (v) hydrogen embrittlement mechanisms, and (vi) various microstructure and mechanical property outcomes of additive and conventional manufacturing processes and their effects on embrittlement.