Overview of nickel-based filler metals for brazing of austenitic stainless steels

For the manufacture of thin-walled precision structures with complex geometry, the method of brazing is used. It allows to obtain joints with a given structural-phase state, high mechanical characteristics and resistance to corrosion. This overview examines alloys based on copper, precious metals, nickel and iron, which are actively used for joining steels. The data on the operational characteristics of the joints obtained by brazing using nickel- based filler metals are presented and structured. Special attention is paid to nickel braze alloys based on Ni - B, Ni - Si - B, Ni - Cr - B, Ni - Cr - Si, Ni - Cr - Si - B, Ni - Mn, Ni - Cr - P, Ni - Si - Be systems. Such alloys are the most widespread and applicable throughout the world. The overview describes the main phases that are formed in the seams and the heat-affected zones of joints. The dependences of the technological parameters of the process, such as the temperature-time mode of brazing and the size of the gap on the microstructure of the joints and their mechanical characteristics, are shown. The corrosion resistance of steel joints brazed by various nickel-based filler metals is considered. The overview is based on the extensive experience of MEPhI in the production and development of rapidly solidified amorphous-crystalline foils based on nickel. In addition to the world experience, the overview considers works of the research team of the MEPhI laboratory, which has been working on this topic since 1995. This overview will help technologists and designers of energy-intensive equipment to determine the trajectory for the selection of the filler metal composition to obtain the optimal technological parameters, mechanical characteristics and corrosion resistance of the joints applicable to a specific design problem.