Optimizing Resistance Spot Welding Parameters for Vibration Damping Steel Sheets

摘要

In order to meet the growing demand for functionality and comfort 1n vehicles, weight and quietness are major concerns for carmakers and materials suppliers. Noise reduction by damping vibrations can meet both aspects. Therefore, steelmakers have developed vibration damping steel sheets (VDSS), which are a three-layer composite material composed of two steel sheets sandwiching a viscoelastic resin core. Industrial use of VDSS in automobiles usually implies the product can be resistance welded. The intent of this investigation is to set up rules to optimize resistance spot welding of VDSS. Two phenomena are the focus of this research: the reduction of blistering and gas expulsion holes. Different aspects are studied, such as the effect of polymer presence and of electrode shape on welding domain and the evaluation of the influence of a welding schedule on blistering and expulsion holes. It appears that polymer presence has no effect on domain width, but does on its position. Higher frequency of expulsion holes with truncated electrodes can be explained with mechanical considerations. From the influence of short circuit voltage, current delay angle and welding schedule on the frequency of gas expulsion holes, a mechanism responsible for expulsion holes is proposed and optimal welding parameters are given.