Brazing of stainless steels using Cu-Ag-Mn-Zn braze filler: Studies on wettability, mechanical properties, and microstructural aspects

Publication date: 5 May 2017
Source:Materials & Design, Volume 121
Author(s): Venkateswaran T., Vincent Xavier, Sivakumar D., Bhanu Pant, Janaki Ram G.D.
In this study, a Cu-37.5Ag-8Mn-5Zn braze filler with a liquidus temperature of 810°C was used for brazing of Martensitic Stainless Steel (MSS) to AISI 321 Austenitic Stainless Steel (ASS). By providing a layer of Ni coating (5μm) over the base materials, satisfactory wetting and spreading of the braze filler was achieved. Brazing experiments were carried out at different temperatures (835°C to 935°C) for different times (5 to 25min) employing braze foils of different thicknesses (75μm to 300μm) to arrive at the optimum brazing conditions. The joints brazed at 910°C for 15min using a braze foil of 150μm thickness showed the highest lap-shear strength of 213MPa. The microstructure of braze metal consisted of Cu- and Ag-rich solid solution phases with varying amount of Ag/Cu, Mn, Zn, and Ni. The Ni coating was found to minimize the intergranular penetration of the braze metal into the base materials. The changes in tensile properties of the base materials after the brazing thermal cycle were also discussed.

Graphical abstract

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