Effects of shoulder on interfacial bonding during friction stir lap welding of aluminum thin sheets using tool without pin

来源期刊：中国有色金属学报(英文版)2010年第12期

论文作者：张贵锋 苏伟 张军 韦中新 张建勋

文章页码：2223 - 2228

Key words：friction stir lap welding; forging action; torsion action; boundary effect; interfacial wear; oxide disruption

Abstract: To separately investigate the potential effects of shoulder on increasing interfacial bonded area and its mechanism, friction stir lap welding (FSLW) of 1.8 mm thick Al sheets without and with insert (copper foil or Al-12Si powders) was conducted using a special tool without pin, respectively. All the FSLW joints (without insert) fractured within top sheet but not along faying surface, suggesting that the shoulder plays an important role comparable or superior to pin in FSLW of thin sheets. Using several specially designed experimental techniques, the presence of forging and torsion actions of shoulder was demonstrated. The fracture surface of the joints with inserts indicates that interfacial wear occurs, which results in the oxide film disruption and vertically interfacial mixing over the area forged by shoulder with a larger diameter than a general pin, especially at the boundary region of weld. The boundary effect can be induced and enhanced by forging effect and torsion effect.