Product Code: PIC2008_701

Studies on the Effect of Welding Current in Laser-Plasma Arc Hybrid Welding of an Al-Li Alloy
Authors:
Baohua Chang, Tsinghua University; Beijing Peoples Republic of China
Jing Zhou, Tsinghua University; Beijing Peoples Republic of China
Zhining Li, Tsinghua University; Beijing Peoples Republic of China
Dong Du, Tsinghua University; Beijing Peoples Republic of China
Presented at PICALO 2008

Laser-plasma arc hybrid welding has high intensity heat source, high welding speed and good gap-bridging capability, and it is a promising technology in production of thin-walled structure of aluminum alloy in aerospace industry. This paper aims to solve the weld porosity problem in welding of Al-Li alloy based on studies on the characteristics of heat transfer during welding. Firstly, a heat transfer model on laser-plasma arc welding is put forward, which takes into account the interaction between laser beam and plasma arc under different distances. Based on the model, the shape, dimensions and stay time of liquid weld pool during hybrid welding of Al-Li alloy sheet is obtained by FEM computation under various welding speed and welding currents. Meanwhile, the porosity in the joints was tested with X-ray. Results show that the porosity increases with the increasing of welding speed and decrease with the increasing of welding currents. The porosity has good correlation with the stay time of weld pool, which indicates the porosity is caused by hydrogen but not turbulence in weld pool. The present paper is beneficial for the process optimization and quality improvement of the hybrid welding of Al-Li alloy.