Fatigue life prediction of laser-MIG hybrid welded 7075-T6 Al alloy joints

Fatigue crack propogation life of laser-MIG hybrid welded 7075-T6 Al alloy thin plate was investigated, and the relation of heat input and elastic modulus was established by experiments. Moreover, the fatigue life was predicted with different heat input. Based on the improved forman equation, an integrated fatigue life model was formulated with the coupling effect of the property difference, threshold of stress intensity factor, driving force of cracking and residual stress of hybrid welded 7075-T6 joints. This novel model was then validated through real fracture propagation, tensile tests and finite element simulation. It has been proved that the predicted fatigue life shows a good agreement with experimental results.