Achievement of defect-free and high-properties Multilayer copper foils soft connection by Friction Stir Welding

Abstract

The connection of new energy vehicle batteries often involves a copper soft connection. In this experiment, Friction Stir Welding (FSW) of multilayer copper foils (TU1) were proposed for the research of copper soft connection. It studies the correlation between microhardness profiles, conductivity test data, welding morphology and process parameters. When the rotation speed increased from 300,600,900,1200 rpm to 1500 rpm, the copper color of the weld changes, and the welding morphology is better at the parameter of 900 rpm-80 mm/min. Elongated grains were processed into fine equiaxed and recrystallized grains by FSW. Continuous dynamic recrystallization (CDRX) was the main restoration mechanism responsible for the microstructural evolution in the NZ. After 900 rpm-80 mm/min FSW of multilayer copper foils, the hardness of the welding zone increases 23 HV and the conductivity decreases 22 IACS. After friction stir welding, the hardness value is the opposite trend of ω/v changes, and conductivity value is the similar change trend of ω/v changes in the NZ.