POURANVARI Majid Islamic Azad University

Spoluautoři SALIMI Zahra

The objective of this paper is to investigate and analyze the transition criteria from interfacial to pullout failure mode in AHSS resistance spot welds during the tensile-shear test. Spot welds were made on three dual phase steel grades including DP600, DP780 and DP980. Correlations among critical fusion zone (FZ) size required to ensure the pullout failure mode, weld microstructure and weld hardness characteristics were developed. It was found that critical FZ size increases in the order of DP600, DP980 and DP780. It was concluded that low hardness ratio of FZ to pullout failure location and high susceptibility to form shrinkage voids are two primary reasons for high tendency of AHSS to fail in interfacial mode. HAZ softening promotes PF mode at smaller FZ sizes. This fact can explain smaller critical FZ size measured for DP980 in comparison with DP780.