Comparative study on laser brazing of austenitic and martensitic stainless steels with silver-based filler metal

In the present study, laser brazing of austenitic stainless steel (type 321) and martensitic stainless steel (type 410) have been performed using 400W pulsed Nd:YAG laser with silverbased filler metal. The microstructure was investigated using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). The laser brazed joints consist of α-Ag solid solution, α′-Cu solid solution surrounded by the α-Ag solid solution and eutectic structure. Filler metal shows better spreading on 321 stainless steel because of more content of Ni and presence of Ti as an activator in the alloy. The average thickness of reaction layer is approximately 3.2 μm for 321 stainless steel and 2.2 μm for 410 stainless steel. The tensile strength of 321 stainless steel joints is higher than that of 410 stainless steel joints due to higher thickness of reaction layer, more spreading and smaller wetting angle. The average of micro hardness for joints in a seam is approximately 146 HV. K e y w o r d s: plaser brazing, 321 stainless steel, 410 stainless steel, silver-based filler metal, pulsed Nd:YAG laser