Dissolving brittle phases in Ni-based filler metals by adding W

Abstract

Brazing hot work steel is a popular method used in the production of casting tools. Usually, Ni-based alloy Ni 620 serves as the preferred filler metal. However, incorporating metalloids such as B and Si to lower the melting point can result in unwanted intermetallic phase formation within the joint. These phases can adversely affect the mechanical characteristics. Hence, it is vital to reduce intermetallic phase formation during brazing to maintain optimal mechanical properties. The research concentrates on W inoculation of Ni 620 to alter the microstructure of the joint. The alloys are produced via melt spinning, and their solidus and liquidus temperatures are investigated using DSC measurements. Next, X37CrMoV5-1 hot work steel samples are brazed in a vacuum furnace. The microstructure is then studied using SEM/EDS, and their hardness properties are evaluated using nanoindentation. Furthermore, their strength is analyzed in the shear test. Incorporating W into Ni 620 when brazing hot work steel alters the presence of brittle phases and hardness characteristics. Particularly, introducing W leads to a significant decrease in hardness, resulting in a more even distribution of hardness throughout the joining area. Using W to modify Ni 620 proves to be advantageous for improving hardness properties when brazing hot work steel.