Laser brazing of Inconel 718 and Inconel 600 with BNi-2 nickel-based filler metal

Abstract

In this study, laser brazing of precipitation hardening nickel-based alloy (Inconel 718) and solid-solution nickel-based alloy (Inconel 600) with the nickel-based filler metal (BNi-2) using a 400-W pulsed Nd:YAG laser was investigated. A laser brazing process was performed 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) equipped with an energy-dispersive X-ray spectroscopy (EDS). Mechanical properties of the brazed joints were measured in the form of micro hardness and tensile test. Results show that the 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 near the interface with substrates. The filler metal shows good wetting and spreading on Inconel 718 and Inconel 600 substrates in a laser brazing process. The average micro hardness for the filler metal was 550 HV compared to 500 HV for the laser-brazed joints. The tensile strength of the laser-brazed joints varied from 200 up to 500 MPa because of different gap distances.