Hydrogen Embrittlement Failure Behavior of Fatigue-Damaged Welded TC4 Alloy Joints

Abstract

The interaction between fatigue damage and hydrogen in TC4 welded joints was analyzed considering specimens with different pre-cycles. The fracture failure caused by hydrogen-induced fatigue damage was investigated using tensile testing and microstructural observations. The results indicate that increasing the number of pre-cycles increases the specimens’ initial dislocation density, enhancing the severity of the hydrogen-induced embrittlement phenomenon. The hydrogen-enhanced local plasticity mechanism, manifested by fracture along the grain boundary, dominates the tensile process in fatigue-damaged hydrogen-filled welded joints after 10,000 and 20,000 pre-cycles. After 30,000 pre-cycles, the hydrogen-enhanced decohesion mechanism dominates the tensile process, manifesting as a transgranular cleavage decoupling fracture.