Study of Dynamic Resistance Curves in Resistance Spot and Seam Welding

Resistance welding involves complex interactions between material characteristics, thermal mechanical and electromagnetic phenomena. The occuring during spot weld formation (break down of surface asperities, molten nugget formation negget growth and mechanical collapse) can be understood through dynamic resistance curves. In seam welding speed and current are very improtant the limiting factor of welding speed is the surface splash. In practical terms, the significance of dynamic resistance curves lies in their possible use in monitoring weld quality. These can be very effectively utilised for the initial selection of the welding variables. In a welding such curve is characterised by initial peak of resistance followed by resistance drop, secondary peak, and ultimately stable condition. Studies are made in mild steel