Measurements of fluid flow on keyhole front during laser welding

Abstract

This paper presents the results of a high speed video survey of melt flow on the front face of a keyhole created during fibre laser welding. Using fast Fourier transform techniques, quantitative values of fluid flow velocities down the keyhole front have been established. The results have led to a phenomenological understanding of some of the quality problems which arise at excess welding speeds. The downward flow velocity on the keyhole front is found to be generally independent of welding speed, and proportional to laser power.

Keywords:

• Fibre laser
• Keyhole welding
• High speed camera
• Flow measurement
• Fast Fourier transform

This research has been carried out in the FiberTube Advanced Project, funded by VINNOVA (The Swedish Agency for Innovation Systems) and Jernkontoret (The Swedish Steel Producers Association) (project no. 34013).