Fatigue analysis and performance evaluation of stainless-steel-cruciform-joint with welding pore defect

Stainless steel cruciform welded joints with pre-embedded pore defects were fabricated for fatigue testing in this study. A finite element model for fatigue damage evolution, accounting for the different fatigue properties of the base metal and molten pool material, was established, and the validity of the finite element analysis (FEA) method was verified. The effects of pore location, pore size, and fatigue stress amplitude on fatigue strength and failure modes were further investigated. The results indicated that different pore locations might lead to weld toe and weld failure modes, with fatigue strengths of 101.7 MPa and 132.0 MPa, respectively. The FEA fatigue damage evolution model effectively predicted the fatigue life of cruciform stainless steel welded joint specimens with pore defects. The most detrimental position occurred when the pore was located in the sub-surface of the molten pool near the weld toe, resulting in weld failure modes under high stress amplitudes. Finally, by combining the fatigue performance under both failure modes, an S-N curve envelope was proposed to evaluate fatigue performance when the location of pore defects was unknown.