FATIGUE CRACK GROWTH IN CRUCIFORM WELDED JOINTS

Fatigue crack growth in cruciform MMA and MIG welded joints containing lack of penetration (LOP) defects in 12.5mm thickness structural steel (0.18%C, 0.7%Mn) was investigated. Welding procedures, and yield, tensile and impact strengths of plate and welds are noted. Fatigue tests were conducted, and loading, plate edge preparation, LOP and fillet lengths and LOP length between fillets were varied. Crack length was measured. Microstructure and fracture surfaces were examined by optical and SEM methods. The stress intensity factor and its relation to crack growth rate were calculated.