Vacuum Brazing of Zirconium-Based Alloy and ۳۲۱ Stainless Steel Using Titanium Based Filler Metal

Both Zirconium-based alloys and ۳۲۱stainless 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 (Zr۳Fe, ZrFe۲ and Zr۲Fe) 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 ۸۲۰, ۸۵۰, ۸۶۵ºC and ۳, ۵, ۷ and ۱۰ min. Also, joining of these two alloys was carried out at ۸۵۰ and ۸۶۵ºC for ۱۰ and ۱۵ 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 ۲۰ ºC/min heating and cooling rates at ۸۵۰ºC and ۱۰ min brazing condition lead to a proper joint without any brittle intermetallic compounds.

Keywords:

Brazing , Stainless steel ۳۲۱ , Zirconium base alloys , Filler Metal , Intermetallic compounds