Temperature field and microstructure characterization of AA6061/H70 dissimilar thermo-compensated resistance spot welds having different joint configurations

• DOI: 10.1016/j.jmapro.2017.06.014
• Publication Date: 2017-07-13T07:16:24Z
• Authors: Yu Zhang; He Shan; Zhen Luo; Yang Li; Jing Bi; Jing Guo; Feng Gao
• Keywords: Spot welding

Abstract Two types of dissimilar AA6061/H70 thermo-compensated resistance-spot-welding joint configuration are designed. Thermal-electric coupled finite element models are built to reveal the temperature field of these two types of joint. An AISI 201 stainless-steel thermo-compensated sheet assists resistance spot welding through heat conduction. The nugget formation is mainly due to conductive heat from this cover sheet when the thermo-compensated sheet is set adjacent to the AA6061 workpiece (type A joint) and is driven by both Joule heat and conducted heat when the cover sheet is set adjacent to the H70 workpiece (type B joint). To ensure the nugget formation, the conducted heat portion requires a long welding time while the Joule heat portion requires a high welding current. The type B joint configuration has higher Cu and Zn contents in the fusion zone, which leads to a high intermetallic content in the Al-Cu-Zn ternary system existing in the nugget. Most type A joints thus have a higher peak load than type B joints in tensile shear tests.