High Strain Rate Properties of DQSK GI Steel Spot Welds

Abstract

This research characterizes the high strain rate compressive loading behavior of DQSK GI steel and its spot welds using the split Hopkinson pressure bar apparatus. Such high strain rate properties of weldments are needed to evaluate the mechanical response of a spot welded structure, such as an automobile body, when subjected to dynamic loads as during a crash. The true stress-strain response of the spot welds and the parent sheet metal has been obtained by analyzing the strain history obtained from the Hopkinson bar and using the Johnson-Cook constitutive model. The findings provide an understanding of the differences between the strain rate sensitivity of the base metal and spot-welded metal. The effect of strain rate on the microstructure and microhardness of the two materials has also been examined.