Correlation between the spatters and evaporation vapor on the front keyhole wall during fiber laser keyhole welding

Abstract

Severe spattering is one of the common problems during fiber laser keyhole welding. In this study, the correlation between the spatter formation and laser-induced evaporation vapor on the front keyhole wall (FKW) was studied by changing the welding speed during fiber laser keyhole welding. The spatters were mainly generated in front of and behind the keyhole mouth, and the diameters of spatters were mainly between 50~100 μm at low welding speed, while the diameters of spatter particles were mainly between 100~150 μm at high welding speed. As the welding speed was increased, the tilt angle of the FKW decreased gradually, and the main spatter generation position shifted from in front of the keyhole mouth to behind the keyhole mouth. In low welding speed, the spatter velocity was higher than that in high welding speed. Further analysis shows that, the recoil pressure of laser-induced evaporation squeezed the molten metal layer in the FKW to generate spatters in front of the keyhole mouth in low welding speed. In high welding speed, the decrease of the molten metal layer in the FKW led to the decrease of spatters in front of the keyhole mouth; however, the laser-induced evaporation vapor from the FKW was more liable to impact the rear keyhole wall to generate spatters behind the keyhole mouth.

Keywords

• Fiber laser welding
• Spatter
• Keyhole
• Evaporation vapor
• FKW