On the feasibility of AISI 304 stainless steel laser welding with metal powder

Laser welding is a manufacturing process that allows the joining of metallic parts even if accurate positioning and preparation of the welding edges are mandatory for successful welding. The use of a filler material in the form either of wire or powder can mitigate the drawback entangled with that preparation. In this work, bead-on-plates were performed on of AISI 304 stainless steel plate with AISI 316 L powder as filler material. Tests were carried out using different combinations of process parameters. The influence of process parameters like laser power, translation speed, powder feed rate, carrier gas flow rate and laser spot diameter on geometry, on microstructure and on porosity of the weld seams were investigated. The transition between conduction to keyhole regime was detected, both with and without powder addition during welding. It was found that the variation of laser spot diameter is fundamental in generating the different welding regimes. Moreover, porosity was detected only in the keyhole regime with a maximum value of 5.5%. Finally, “V-shaped” grooves were machined on AISI 304 substrate and filled by two overlapped tracks. The results of the study demonstrated the feasibility of the laser welding of AISI 304 stainless steel with AISI 316 L powder as filler material.