Weld strength and process controllability for laser welding of thin sheet metals

Laser welding is a promising technique for joining of thin sheet metal due to its precise heat input control, and the optimized welds should have the desired strength and minimum overheating. The optimum weld depth for maximum weld strength is studied by developing a geometrical model and conducting tensile-shear tests on lap welded thin stainless steel sheets of 100 mum thickness. The results show that to a large extent the strength of lap welds is influenced by the weld geometry. A three-dimensional quasisteady state heat conduction model is presented to predict the weld geometry produced in conduction laser welding of thin sheets under different process parameters. The controllability of weld depth is studied experimentally and theoretically by varying the laser power. A process parameter region has been identified for difficult control of the welding process. (C) 2000 Laser Institute of America. [S1042-346X(00)00206-0]