Numerical simulation on deformation and stress variation in resistance spot welding of dual-phase steel

Abstract

In this study, an effective numerical simulation on resistance spot welding of dual-phase steel was conducted. The electrical, thermal and mechanical behaviours during squeezing, welding and holding stages were analyzed, respectively. Large lath martensite was formed in the fusion zone during the experiment. A good agreement on nugget development was obtained between numerical and experimental results. The size of contact region and pattern of contact pressure distribution at the squeezing stage were found to be force-independent. The variation of contact pressure distribution during the welding process was interpreted combining the temperature and deformation distribution of the workpiece. The contact pressure at both edges of contact interfaces was reconcentrated after nugget formation. The compressive state of axial and radial stress at the weld nugget was explained through the thermal expansion mismatch and the electrode force effect. The plastic annulus and notch between workpieces were also successfully simulated.