Laser surface texturing of structural components for residual stress alleviation during ultrashort pulsed laser welding

Ultrashort pulsed laser welding of dissimilar materials is an attractive alternative to currently used adhesive bonding of metal-glass components in the manufacture of lasers and other precision optical systems. The process uses a mixture of very high peak power to drive the process and sufficient average power to provide thermal accumulation. The major limitation of this process is associated with stringent surface finish requirements and the typically high thermal expansion coefficient mismatch of the two materials, that can result in low bond strengths and low part survivability during thermal cycling tests.

In order to develop a more robust process and improve yield we have investigated laser surface texturing to pre-process the metal surface, together with better optimised laser scanning patterns. The aim is to reduce the residual stresses developed in the glass component during the laser welding process. The results from a thermo-mechanical model are used to inform this approach.