High power diode pumped Nd:YAG laser welding of medium section low carbon martensitic stainless steel

This paper describes laser beam welding of medium section, i.e. 6 mm thick low carbon martensitic stainless steel EN-1.4418. The welds are made by using a high power diode pumped Nd:YAG laser and a fiber optic beam delivery system. A variety of shielding gases as nitrogen, argon and mixtures of argon with small amounts of oxygen or hydrogen have been applied to investigate their influence on the weld quality. It is found that the best weld quality is achieved by using nitrogen as shielding gas. Successful welds show no porosity and are performed by using no additional material. In order to evaluate the weld quality, X-ray analysis of welds as well as optical microscopy of transverse and longitudinal weld cross sections have been made.