Product Code: PIC2008_P115

The Research on the Parameter Thresholds of Titanium Alloy Laser Welding
Authors:
Chen Li, Bamtri; Beijing Peoples Republic of China
Gong Shuili, National Key Lab for High Density Beam Processing Technology ; Beijing Peoples Republic of China
Yao Wei, National Key Lab for High Density Beam Processing Technology ; Beijing Peoples Republic of China
Presented at PICALO 2008

The process of laser penetration welding of titanium alloy sheet involves complex reactions among the laser-plasma- material, periodical keyhole opening and closing, and melt pool flowing behavior. This process can be mapped into pool morphology and weld shape. It is well known that the mode of laser welding depend on laser power density. However, according to this study on the weld shape of BT20TC4 and Ti-23Al-17Nb titanium alloy laser welding, the laser welding mode is not only related to the laser power density but also the heat input. Both laser power density and heat input determine the keyhole stability, melt pool behavior and weld shape of laser welding titanium alloy. The research shows that when the laser power density and heat input exceeded the threshold of full penetration laser welding of titanium alloy, hourglass shape weld was obtained. The back width to surface width ratio (Rw) reflected the full penetration stability of the laser welding process of titanium alloy sheet. According to the results in this paper, the condition for stable full penetration laser welding of BT20 titanium alloy of thickness of 2.5mm was that the Rw should be bigger than 0.4. Based on it, a parameter window of laser power -laser welding speed and laser power density-heat input threshold curves for stable full penetration laser welding were obtained.