Investigation of effective parameters on dissimilar infrared brazing for Ti-6Al-4Vv and SS316 L by Ag Base filler metal

Both Ti-6Al-4V and 316L stainless steels are widely used as engineering alloys in many modern industries, especially aerospace, gas turbine engines and heat exchangers due to high mechanical properties, high creep, fatigue, and corrosion resistance. Fusion welding of these alloys is not easily possible due to their incomplete solubility in each other. Brazing is one of the best choices for joining dissimilar alloys. Infrared brazing is a novel process characterized with a high heating rate up to 500 °C/min. Accordingly, it is expected that both erosion of the substrate and excessive growth of intermetallic phases in the brazed joint are significantly decreased. This study is focused on the infrared brazing of Ti-6Al-4V and 316L stainless steel to investigate the influence of brazing parameters (brazing alloy, temperature and time) on microstructure and mechanical properties of base metals with CBS 34 (Ag-based) braze filler foils. Brazing was performed in a home-made infrared furnace at temperatures of 750, 780, 800, 850 and 900 °C for 3-5 min. Qualities of the brazed joints were evaluated by microstructure and phase constitution of the bonded joints with light optical microscope (LOM) and scanning electron microscope (SEM). Mechanical properties of the brazed joints were evaluated by hardness test. The optimum brazing parameters were at 850 °C-5 min for CBS 34 filler foils.