Infrared Dissimilar Joining of Ti50Ni50 and 316L Stainless Steel with Copper Barrier Layer in between Two Silver-Based Fillers

Abstract

Infrared dissimilar joining Ti 50 Ni 50 and 316L stainless steel using Cu foil in between Cusil-ABA and BAg-8 filler metals has been studied. The Cu foil serves as a barrier layer with thicknesses of 70 µm and 50 µm, and it successfully isolates the interfacial reaction between Ti and Fe at the 316L SS (stainless steel) substrate side. In contrast, the Cu foil with 25 µm in thickness is completely dissolved into the braze melt during brazing and fails to be a barrier layer. A layer of (Cu x Ni 1−x ) 2 Ti intermetallic is formed at the Ti 50 Ni 50 substrate side, and the Cu interlayer is dissolved into the Cusil-ABA melt to from a few proeutectic Cu particles for all specimens. For the 316L SS substrate side, no interfacial layer is observed and (Ag, Cu) eutectic dominates the brazed joint for 70 µm/50 µm Cu foil. The average shear strength of the bond with Cu barrier layer is greatly increased compared with that without Cu. The brazed joints with a 50 µm Cu layer demonstrate the highest average shear strengths of 354 MPa and 349 MPa for samples joined at 820 • C and 850 • C, respectively. Cracks are initiated/propagated in (Ag, Cu) eutectic next to the 316L substrate side featured with ductile dimple fracture. It shows great potential for industrial application.

Infrared Brazed Joints of Ti50Ni50 Shape Memory Alloy and Ti-15-3 Alloy Using Two Ag-Based Fillers

“…The wetting angle approached zero after 70 s in both test conditions. Unlike the BAg-8 filler metal, the Ticusil ® alloyed with 4.5 wt.% Ti active ingredient, which greatly ameliorates wetting on both Ti-15-3 and Ti 50 Ni 50 substrates [21].…”

“…The wettability of braze melt on the base metal and reaction(s) at the interface between the braze melt and base metal must both be considered in filler metal selection. According to previous studies, many titanium alloys are well brazed with Ag-based braze alloys [18,19,20,21]. However, the Ag-Cu eutectic melt cannot effectively wet the Ti 50 Ni 50 substrate unless the active ingredient, Ti, is alloyed into the braze [22].…”

Novel Research for Development of Shape Memory Alloys

“…Shiue et al studied the infrared dissimilar joining Ti 50 Ni 50 and 316L stainless steel using Cu foil in between Cusil-ABA and BAg-8 filler metals [24]. This study indicates great potential for industrial applications.…”