Laser brazing of 321 and 410 stainless steels using BNi-2 nickel-based filler metal

In this paper, laser brazing of austenitic stainless steel (type 321) and martensitic stainless steel (type 410) was performed using 400W pulsed Nd:YAG laser with nickel-based filler metal (BNi-2). Laser brazing process was carried out at different gap distances. Microstructure and composition analysis of the filler metal and the brazed joints were examined by optical Microscopy (OM) and Scanning Electron Microscopy (SEM). Mechanical properties of the brazed joints were measured in the form of Micro hardness and tensile test. Results show that filler metal shows good wetting and spreading on 321 and 410 stainless steel in laser brazing process. Filler metal consists of nickel solid solution, nickel-rich boride and chromium-rich boride. The laser brazed joints are mainly comprised of the nickel solid solution, nickel-rich boride in the center of the joints and chromium-rich boride in near interface with substrates. The average micro hardness for filler metal was 550 HV compared to 500 HV for laser brazed joints. The tensile strength of laser brazed joints is varied from 200 to 500 MPa because of different gap distances.