Study on High Power Fiber Laser Welding Technology of TA5 Titanium Alloy

High power fiber laser welding was conducted on TA5 titanium alloy with 10 mm in thickness. High speed photography was used to investigate the effect of the laser welding plume on the welding process. The results show that when the laser power reaches 3-4 kW, the plume become serious, and the splash and soot increase obviously in amount. The weld metallography test manifests that the weld section is “wedge-shaped” when the laser power is low, while the weld section becomes “funnel shaped” when the laser power is larger than 6 kW. When the laser power is 10-11 kW, and the welding speed is 1100-1500 mm/min, an excellent “keyhole” welding joint is obtained, and the welding seam is of typical high-energy beam joint shape with a large ratio of depth to width up to 2:1. RT and PT tests show that the weld seam can satisfy NDT (non-destructive test) standard. The mechanical test indicates that the strength of the welded joints can reach 800 MPa, which can meet the bending standard. The fracture dimple is obvious, which indicates its ductile fracture. Metallographic test exhibits that the section of weld zone is “girdle-shaped” morphology and the columnar crystal zones are obvious, with an obvious competitive growth of mode of each columnar crystal zone. The weld zone is mainly composed of serrated α+punctate β. The hardness test shows that the hardness of the weld zone is slightly higher than that of base metal, and that of the heat-affected zone is the lowest, which can satisfy the hardness requirements of titanium alloy joints. © 2024 Science Press. All rights reserved.