A welding method has been developed that makes use of fundamental mode laser pulses. These pulses show single-mode relaxation oscillations with a high peak power first spike causing breakdown of the material surface. The laser emission following the first spike can be adapted to the welding requirements and the material properties. Metallurgical problems of intermixing of dissimilar materials in the weld puddle have been investigated with an electron beam microprobe analysis. In the case of materials which normally show bad weldability uniform welds with maximum strength could be achieved by local addition of welding agents to the weld puddle. The lap weld of a stainless-steel spring with a nickel-iron baseplate has been performed with Nb as welding agent.