Analysis of back-weld spatters in laser welding of CP-Ti

摘要

The laser welding of commercial grades of pure titanium plate TA2 with 0.5 mm was taken, and the back area of the molten pool was photographed by high-speed camera. Also, the reasons of back spatters were studied. Spatters on the back side of the plate have three main types: continuous spatters, periodic spatters and no spatters. All continuous back spatters are accompanied by the appearance of keyhole, and the keyhole can be observed at the moment when periodic spatters appear. The downward shear stress applied by the downward jet of metal vapor from the keyhole is an important reason for backside spatter. Increased laser power or welding speed will increase shear force, eventually contributing to more spatters. When the defocused distance is increased to 30 mm, the keyhole is completely obscured on the back side, so there is no spatter at this time.