FATIGUE CRACK-GROWTH BEHAVIOR OF WELDED CRUCIFORM JOINTS

Fatigue life evaluations have been carried out on load carrying cruciform joints with lack of penetration (LOP) defects. The joints were fabricated using manual metal arc (MMA) and metal inert gas (MIG) welding processes. In the case of MIG a single pass and MMA welded joints a multi-pass technique were used with similar type of filler metal. The fatigue life of both types of welded joints were evaluated on the basis of fracture mechanics and conventional method (S-N curve) and their respective fatigue crack growth behaviour and fatigue life were compared. The implication of metallurgical parameters of weld metal on fatigue crack growing from toe and root region of the joint were examined and analysed with the help of existing theories. How the specific location of cracking could affect the life of the joints was also highlighted.