Evaluation of Tensio n - Shear Stress for zig -zag spot welds by using indirect resistance spot weld technique for fabrication industries

Abstract

All resistance welding processes are based on the heat that is produced at the interface due to resistance for the flow of electric current through the metal parts being joined. The amount of heat generated basically depends on the magnitude of the current, the duration of current flow and the load transmitted to the inter face. Spot welding is now a very established process in which two sheets to be welded are kept one over the other to get a nugget at the interface. The contact resistance at the interface dictates the quantum of heat that is generated . New concept namely indirect resistance spot welding was developed for applications where the surface appearance on sheet can be critical. In this process outer surface, limiting the extent of electrode indentation is traditionally managed by controlling the heat balance and electrode size. Trials were conducted, for optimum weld parameters for cold rolled carbon steel sheet, for Zig – zag spot weld for the indirect spot welding and also observed the Reduced Tensile stress for the base metal. This research paper reports the results of the trials, under optimum weld parameters. indirect resistance spot welding .The observations on Tension – shear breaking load , nugget diameter ,yield stress, reduced tensile stress, working stress or design stress by considering minimum factor of safety of two, for Tension shear application for indirect resistance spot welding were discussed. Peel test was done to find quantitatively, the formation of nugget and nature of failure. This paper reveals the results for the Zig – zag spot for the indirect spot welding, process were observed more Safe joint specially for tension shear application .Since spot welds during design considerations , for Zig – Zag spots for lap joint for tension shear applications these results will be most useful for optimum design.