Characterization of resistance spot welded transformation induced plasticity (TRIP) steels with different silicon and carbon contents

Abstract

This research work examines the influence of chemical composition and microstructure of 6 differenttransformation induced plasticity (TRIP) steels on the mechanical behavior of resistance spot weldments.The microstructure of the spot welds was characterized by means of scanning electron microscopy and X-ray diffraction techniques. The mechanical properties were assessed under lap-shear tensile and hardnesstesting. Results indicated that the nugget width is strongly correlated with the type of failure mode of thespot welds. The mechanical properties exhibited by the spot weldments are related with the partitioningbehavior of chemical elements specially Si and C present in the steels during the cooling stage of theresistance spot welding process. X-ray diffraction study indicated traces of retained austenite in the heataffected zones of the spot welds of those steels with Si-enriched chemical composition where intercriticalannealing temperatures were closer to Ac1