Influence of hydrogen embrittlement on the fatigue behaviour of 316L stainless steel welded joints

Hydrogen embrittlement (HE) is a critical issue affecting the structural integrity of materials, including welded joints, used in hydrogen storage and transportation. In this study, the influence of HE on the fatigue behavior of 316L austenitic stainless-steel welded joints was investigated. Tensile and fatigue tests were performed on base material, welded joints, and hydrogen-charged welded joints to assess the degradation in their mechanical properties. The results revealed that welding significantly reduced the fatigue strength of the material, and the presence of hydrogen further intensified this effect. Microstructural analysis confirmed the formation of austenitic-ferritic duplex microstructures in the weld bead, with delta ferrite improving resistance to hot cracking but increasing susceptibility to HE. Fractographic examination of weld beads exposed to hydrogen charging showed characteristic hydrogen-induced cracking. • Hydrogen embrittlement weakens 316L stainless steel welded joints. • Welding reduces fatigue strength, worsened by hydrogen exposure. • Delta ferrite aids hot cracking resistance but raises HE risk. • SEM analysis reveals hydrogen-induced cracking in weld beads. • HE mitigation requires welding optimization and filler control.