Microstructure and Properties of 2219 Aluminum Alloy Welded Joint Produced by Double-Pulsed VP–GTAW Process
CONG Baoqiang1,2, FAN Tao1,2, QI Bojin1,2, WANG Yipeng1,2, QI Zewu1,2
1. School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China;
2. MIIT Key Laboratory of Aeronautics Intelligent Manufacturing, Beijing 100191, China
The butt welding experiments were carried out using double-pulsed variable polarity gas tungsten arc welding (VP–GTAW) process with 4mm 2219–T87 high strength aluminum alloy as base metal, and ER2319 Al–Cu wire and ER5087 Al–Mg wire as filler wire, respectively. The microstructure and mechanical properties of welded joints were investigated. The results show that double-pulsed VP–GTAW process has benefits on refining grain size and improving mechanical properties. The maximum tensile strength and elongation can be achieved when the frequency of low-frequency pulse frequency is 2Hz. The tensile strength and microhardness of the 2219 aluminum alloy welded joints using Al–Mg wire are superior to that using Al–Cu wire with similar plastic property. The maximum tensile strength is 328MPa, which is 72% of base metal. The microhardness of weld zone is above 100HV. Fracture pattern of all welded joints is mixed fracture of brittle and ductile.