Product Code: ICAL08_710

An Assessment of the Welding Performance of High-Brightness Lasers and a Comparison with In-Vacuum Electron Beams
Authors:
Geert Verhaeghe, The Welding Institute; Cambridge Great Britain
Bruce Dance, Electron Beam Group; Cambridge Great Britain
Presented at ICALEO 2008

A unique experiment carried out at TWI a few years ago compared the welding performance of a number of fibre-delivered lasers with beam qualities ranging between 4 and 23mm.mrad, under identical processing conditions, and demonstrated the effect of laser beam brightness, together with beam quality and spot diameter, on the welding performance of both steel and aluminium. This paper describes a continuation of this earlier study, comparing, against these initial results, the welding performances of laser beams with even higher beam qualities (higher brightness) and of an electron beam (in vacuum) carried out under the same processing conditions. The work confirms the presence of a mechanism, operating up to a considerable distance above the processing point, causing absorption and/or scattering of the incident laser power, thereby limiting the welding performance of a high-brightness laser beam. It is demonstrated that this limitation to the welding performance can be overcome, by practical means, thereby maximising the welding capability of a high-brightness laser. Under similar conditions of the process (power, spot and speed) and beam (brightness), it is also shown that the welding performance of a high-brightness laser can equal, or in some cases exceed, that achievable with in-vacuum electron beam welding.