Effect of partial rolling on the microstructure, mechanical properties and fracture behavior of AZ31 Mg alloy joints

Partial rolling processes at different temperatures were conducted on the fusion zone (FZ) of double-side welded Mg-3Al-1Zn alloy joints with excess weld bead. The effect of rolling reduction and rolling temperature on the microstructure, mechanical properties and fracture behavior of the joints were investigated. Results show that both the strength and elongation of the joints increase significantly with rolling reduction owing to the microstructure evolution in the FZ. Once rolling reduction exceeds a critical value (CRR), tensile fracture location will be transferred from the FZ to the substrate and the joints can achieve tensile properties roughly the same as those of the initial substrate. Rolling at a lower temperature is preferred to obtaining a weak basal texture in the FZ, for the corresponding CRR is smaller.