Experiments on laser beam welding of sheets of stainless steel to brass sheets were performed using a high power CO 2 -laser. The welds were produced to fulfil various technical and decorative demands in the manufacture of door handles. One requirement was to produce a weld strong enough to withstand a deep drawing process. On the other hand the weld should show a straight and clear borderline between both metals when viewed by the naked eye. Both aims were achieved by the laser welding process used in these experiments. The mechanical properties of the dissimilar metal welds exhibited a higher tensile and yield strength than welds of brass-brass joints. Deep drawing of the welded sheets to form semispherical shells were possible without the welds showing cracks. The intermixing region of the molten weld could be kept below 200 µm enabling a perfect seam after surface finishing.

In this paper the interaction of attosecond laser pulses with matter is investigated. The scattering and motion of heat carriers as well as the external force are considered. The heat transport is described by the thermally forced Klein-Gordon or thermal modified telegraph equation depending on the ratio of the scattering and potential motion. In the case of the thermal Heisenberg type relation V ‰ ∽ E ( ‰ is the relaxation time and V is the potential) the heat transport is described by the thermal distortionless damped wave equation. In this paper the Klein-Gordon, modified telegraph 1 equation and wave equation are solved.

This article presents a thermal finite volume model adapted to investigate laser processes. It is specially developed to treat moving heat sources with phase changes, melting and vapourisation. Heat transfer control in laser processing is particularly useful when processes must respect prescribed temperatures, or more generally, prescribed constraints. These processes involve generally several laser sources, or non-conventional power distribution. Hence, they have numerous parameters to set. Experimental optimisation is difficult and may be expansive. The numerical model is a useful and cheaper tool for development of those complex processes. For example in this article, two special laser processes are investigated: control of high carbon steel welded line cooling, zinc-coated sheets lap welding.