Peak load and energy absorption of DP600 advanced steel resistance spot welds

The paper aims at investigating the microstructure, failure mode transition, peak load and energy absorption of DP600 dual phase steel during the tensile-shear test. It was found that the welding current has profound effect on the load–displacement characteristics. In the low welding current, welds failed in interfacial failure mode. Increasing welding current resulted in sufficient weld nugget growth to promote double-sided pullout failure mode with improved mechanical properties. Further increase in the welding current caused expulsion and failure mode was changed to single-sided pullout with reduced energy absorption capability. It was found that the fusion zone size is the key parameter controlling the mechanical properties of DP600 resistance spot welds in terms of peak load, maximum displacement and failure energy.