Infrared brazing of Ti–6Al–4V and 17-4 PH stainless steel with (Ni)/Cr barrier layer(s)

Ti–6Al–4V and 17-4PH stainless steel (17-4PH SS) with (Ni)/Cr barrier layer(s) were infrared vacuum brazed using two silver-based braze alloys, 72Ag–28Cu and 63Ag–35.25Cu–1.75Ti (wt.%), respectively. Both Cr (15 μm) and Ni (2 μm)/Cr (15 μm) coated 17-4PH SS plates were evaluated in the study. Introducing (Ni)/Cr barrier layer(s) can effectively inhibit the interfacial reaction between the 17-4PH SS and the molten braze during brazing. Therefore, the formation of brittle interfacial Ti–Fe intermetallics next to the 17-4PH SS is avoided and replaced by Ti–Cu–(Ni) and TiCr2 intermetallic compounds in the joint. The average shear strength of the infrared brazed joint with Ni/Cr barrier layers is significantly improved up to 233 MPa. Using (Ni)/Cr barrier layers on the 17-4PH SS has the potential of industrial application in brazing Ti–6Al–4V and 17-4PH SS.