Laser beam micro welding of dissimilar metals

The combination of dissimilar materials like brass and stainless steel is often needed in watch movements due to tribologic aspects. For mass production in automotive applications, a joining technique for alloyed copper with alloyed steel is needed. Laser beam micro welding offers an alternative to conventional joining techniques like press fit or soldering. The laser beam micro welding of stainless steel (X5CrNi1810) to copper (CuNi3SiMg) and brass (CuZn37) with a fiber-guided pulsed Nd:YAG laser is investigated. The weld seams are produced with the SHADOW-Welding: one single pulse with high feed rate by beam movement or part movement. The joint configurations are t-joints. High strength and reproducibility as well as good appearance are the main objective of joining dissimilar metals. Cracks and spatter formation are affected by the different physical properties and should be avoided. The welding results of joint configurations as well as welded parts are presented. The length of the continuous welding seams are up to 15.7 mm at a feed rate of up to 60 m/min. The weld width attained is from 50 to 250 µm and a weld depth from 20 to 150 µm. This low energy joining process with minimized head input results in low distortion of the parts joined.