On the Formation of Intermetallics during the Furnace Brazing of Pure Titanium to 304 Stainless Steel Using Ag (30–50%)–Cu Filler Metals

Abstract

In the present work, the effect of brazing parameters on the properties of the brazed joint of pure titanium and 304 stainless steel (304SS) was investigated. Three different Ag–Cu filler metals were used, while the temperature and time of brazing were in the range of 800–950°C and 5–45 minutes, respectively. The microstructural observations show that, depending on the brazing conditions, different intermetallic phases such as CuTi₂, CuTi, Cu₃Ti₄, and FeTi were formed at the phases interface. Based on the microstructural observations, a model was developed to characterize the formation of phases at the interfaces and brazed joint. The results show that, while some phases may form during the brazing process, the others can form during the cooling cycle after brazing. The results of the mechanical tests indicate that the microstructure of joint has a considerable effect on the shear strength of the brazed samples. It was observed that, when brittle intermetallic phases are finely dispersed at the interface, the strength was lower comparing to the conditions under which the intermetallic phases had a coarse dispersion in the brazed joint.

Keywords:

• Brazing
• Interfaces
• Intermetallics
• Microstructure
• Silver
• Stainless steel
• Strength
• Titanium