Strength and infrared assessment of spot-welded sheets on ferrite steel

This paper addresses the mechanical properties of ferrite steel resistance spot welds during quasi-static tensile test. The mechanical properties are described in terms of peak load. It was shown that the fusion zone size is the most important. The fusion zone size can control the solidification of the grain which controlling factor of spot weld peak load. The dendritic grain and equiaxial axial grains occurred in the microstructures of the welded specimens joined at various welding currents and electrode forces. The failure mechanism of resistance spot welds during tensile test was studied with the aid of thermography. The thermography gives visible data of temperature changes on the surface of specimen. In light of the failure mechanism, the simple model is proposed to ensure pull out failure mode.