The Effect of Welding Parameters on the Microstructure and Microhardness of Resistance Spot Welded Galvannealed Steel Sheets

摘要

Resistance spot welding is used extensively in the automotive industry for producing high volume, low carbon steel joints at a high-production rate. Although resistance spot welding is frequently used in industry, it often results in inconsistent weld quality. This study examines the effect of welding parameters on the microstructure and microhardness of resistance spot welded galvannealed steel. The specimens were welded at various percent currents while holding all other parameters constant. Light microscopy, microhardness testing, nanoindentation measurements, scanning electron microscopy, and x-ray diffraction were used to characterize the welded samples. Microhardness measurements taken across the weld nugget of each sample showed an increase in the microhardness values as the percent current increased. The purpose of this study is to investigate the cause of the observed increase in microhardness.