Effect of welding current on welding quality of M51/B318 dissimilar metal joint using resistance welding

In this study, dissimilar steels of high speed steel M51 and high strength spring steel B318 was welded by the precision resistance welding method. The influence of welding current on four indexes of joint characteristics (shear force, heat influence zone, extrusion slag amount and splash condition) is analyzed emphatically. The results show that the welding current is in parabolic relationship with the shear force of the joint. When the welding current rises from 900 A to 1 300 A, the shear force of the joint increases to a peak value, and when the welding current reaches 1 400 A, the shear force of the joint decreases due to slag spatter result from excessive welding energy. With the increase of welding current. The size of heat affected zone and the amount of molten slag in extrusion increase firsty and then decrease. Finally, the influence of welding current on weld quality is analyzed with microstructure.