Aging and degradation of electrode Cu spot welding

Abstract

This study discusses how the spot welding process that needs to be considered is related to the use of electrodes and the quality of electrodes that can affect the quality of the welding results in the plate, taking into account the mechanical materials, in the welding process by several welding parameters such as welding time, pressure, current, temperature, and others, the electrodes used in pairs with the plate which need to know the age limit of use and the degradation of the electrode in order to control and know the quality of the electrodes and the results of spot welding. The purpose of this study, to determine the age limit of Copper (Cu) electrode use to the low carbon steel plate with a thickness of 1 + 1 mm. microstructure and composition changes of the electrodes at the time of aging and post-degradation and shear strength on the plate during the aging experiments process. The method used was experimental, spot welding process with mechanical load and thermomechanical, electrode with Cu material with tip diameter 5 mm paired with plate using material Fe with thickness (1 + 1 mm), first experiment to know the age limit aging electrode by loading of pressure 5 bar, current 5,7 kA, welding time 0,72 s, and heating 0,3130 Joule, and second experiment is done to know degradation of electrode with loading pressure 5 bar, current 18,810 kA welding time 2,68 s and heating 16,025 Joule. The experimental results of the spot welding process, for the first experiment, resulted in a temperature of 710 °C with 5 bar and a continuous welding process of 500 spots was conducted, and the test results, metallography evaluation and composition of electrode before and after aging experienced changes, in the second experiment on the process welding produces a temperature of 1038°C and pressure of 5 bar, there is a significant change in the electrode surface. The electrode of spot welding Cu paired with plate Fe, and thickness of plate 1+1 mm can be used continuously with 300 spot welds usage limits at temperature 710°C and temperatures occurring at the 900°C degradation threshold, with the recommended pressure parameter of less than 5 bar.