Effect of post weld heat treatment on properties of variable polarity TIG welded AA2219 aluminium alloy joints
(1. School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China;
2. Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300072, China)
2. Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300072, China)
Abstract: AA2219 aluminium alloy joints were fabricated by variable polarity tungsten inert gas (VPTIG) welding process and the effects of post weld heat treatment (PWHT) on the tensile properties, microstructure and fatigue behaviour of the welded joints were investigated. The VPTIG welding process was adopted because it could meet the need of cathode cleaning and meanwhile it could reduce the deterioration of tungsten electrode furthest. The welded samples were divided into as-welded (AW) sample and PWHT sample. The PWHT method used on the samples was solution treatment (535 °C, 30 min), water quenching and artificial aging (175 °C, 12 h). The experimental results show that, compared with the AW samples, the microstructure characteristics and mechanical properties of the AA2219 joints after PWHT were significantly improved. The improvement of yield strength, ultimate tensile strength, and fatigue strength are 42.6%, 43.1% and 18.4%, respectively.
Key words: AA2219 aluminium alloy; variable polarity TIG; post weld heat treatment; mechanical properties; microstructure; fatigue behaviour