Influence of laser-induced plume on penetration in laser welding

Abstract

The influence of a laser-induced plume on penetration is discussed in remote laser welding. Melt-runs accompanying plumes of various lengths were carried out in order to investigate the influence of plume on penetration using a 4.5 kW YAG laser and air knife. Penetration depth obviously reduced in conditions with a long plume. It is considered that the decrease of penetration depth comes from attenuation of laser power in the plume, through the decrease in weld metal cross-sectional area. Attenuation of laser power was estimated at about 7% and focus shift was estimated to be about 0.7 mm in the experimental conditions with a plume of 90-mm length, compared with the conditions with a plume of 11-mm length.

Keywords::

• laser welding
• remote welding
• plume
• penetration depth
• attenuation
• focus shift