Vacuum Brazing of Zirconium-Based Alloy and 321 Stainless Steel Using Titanium Based Filler Metal

Abstract

Both Zirconium-based alloys and 321stainless steel are widely used as engineering alloys due to their good mechanical properties. Conventional fusion welding techniques for Zr alloys and stainless steel are not feasible due to the formation of brittle intermetallic compounds such as (Zr₃Fe, ZrFe₂ and Zr₂Fe) and corrosion cracking. Brazing is one of the most widely used techniques for joining dissimilar alloys.Using titanium base filler metal decreases the diffusion and the formation of brittle intermetallic compounds. In this study, wetting experiments were done at 820, 850, 865ºC and 3, 5, 7 and 10 min. Also, joining of these two alloys was carried out at 850 and 865ºC for 10 and 15 minutes. Optical microscope, scanning electron microscope (SEM), XRD, shear test and micro-hardness test were used for metallurgical and mechanical investigations. The results show that 20 ºC/min heating and cooling rates at 850ºC and 10 min brazing condition lead to a proper joint without any brittle intermetallic compounds.