Laser brazing of Inconel-718 with BNi-2 filler metal

Abstract

Inconel-718 is widely used in the aircraft industry due to its durability and strength. They are constantly subjected to extreme stresses and requires regular maintenance to remain operational. Brazing is commonly used to help repair damaged parts by fusing two metals through heating and melting a brazing alloy that is able to bond the two separate metals together. However, the extreme temperatures to melt the metals could result in microstructural changes. In this project, Inconel-718 superalloy was Transient Liquid Phase (TLP) bonded with BNi-2 as the filler meter, to analyze the effects on the microhardness and tensile strength of Inconel-718. The two metals were brazed at 1015°C for 15 minutes before cooling down to room temperature. Scanning Electron Microscopy (SEM) and Electron Backscatter Diffusion (EBSD) were used in analysing the fractured surfaces and phase composition respectively. The brazed joints had a brazing gap that was above the Maximum Brazing Clearance (MBC), resulting in brittle fracture failure at the joint centreline due to the formation of brittle eutectic phases. The hardness generally increased from the Base Metal to the Brazed Alloy.