The influence of the pressure of Ar shielding gas on the keyhole behavior during CO2 laser welding of TA15

Abstract

Many studies have shown that during laser welding, shielding gases play a key role in protecting the welding area from the surrounding air, and have great effects on energy absorption, keyhole formation, temperature field distribution and so on. Because of these causes, it could finally have some effects on geometry and defect of welds, especially for weld material like Ti-alloy. In the practices, it is found that not only the different gas has great influence on the weld ing results; the pressure also has great influence. In this paper, a series of experiments about CO2 laser welding of TA15 TI-alloy were completed by using Ar as shielding gas at different gas pressure. At the welding processes, the images of vapor/plasma were captured by the high-speed camera. The results show that the pressure of shielding gas has very important influence on geometries of welds to TA15 Ti-alloy. Analyzing the images of vapor/plasma, it is found that the different pressure can change the keyhole behavior. Especially it can change the results of vapor/plasmas erupting fro m the keyhole of back weld, Furthermore, it is found that at different gas pressures, the recoil pressures in the keyhole are quite different. And it is the reason that the pressure influences the welds.Many studies have shown that during laser welding, shielding gases play a key role in protecting the welding area from the surrounding air, and have great effects on energy absorption, keyhole formation, temperature field distribution and so on. Because of these causes, it could finally have some effects on geometry and defect of welds, especially for weld material like Ti-alloy. In the practices, it is found that not only the different gas has great influence on the weld ing results; the pressure also has great influence. In this paper, a series of experiments about CO2 laser welding of TA15 TI-alloy were completed by using Ar as shielding gas at different gas pressure. At the welding processes, the images of vapor/plasma were captured by the high-speed camera. The results show that the pressure of shielding gas has very important influence on geometries of welds to TA15 Ti-alloy. Analyzing the images of vapor/plasma, it is found that the different pressure can change the keyhole behavior. Especially it ...