Fatigue crack propagation behaviour of welded and weld-repaired 5083 aluminium alloy joints

Fatigue crack growth behaviour of 5083-H321 aluminium alloy plates, in unwelded, welded and weld-repaired conditions was investigated using single edge notched tension (SENT) specimens. Propagation rates for cracks in the heat-affected zone for welded specimens and the fusion zone for weld-repaired specimens were determined experimentally. The effects of weld residual stresses were taken into account by means of crack closure evaluation. 3-D finite element models were employed to calculate stress intensity factors in the vicinity of welds applying linear elastic fracture mechanics. Fatigue crack growth tests show that weld residual stresses have a significant influence both for welded and weld-repair plates. Metallurgical examination of the heat-affected zone indicates that weld-repair process can significantly increase the grain size and the size of inner-defects. Crack growth rates of weld-repair plates are greater than that of welded and plain materials.