A resistance welding process that produces a weld at the faying surfaces of overlapped parts progressively along a length of a joint. The weld may be made with overlapping weld nuggets, a continuous weld nugget, or by forging the joint as it is heated to the welding temperature by resistance to the flow of the welding current. See Figures H-4 and R-5. See also HIGH-FREQUENCY SEAM WELDING and INDUCTION SEAM WELDING.