Effects of Cu Powders Contents on Microstructure and Micro-hardness of Stainless Steel Brazed Joint

The composite fillers were composed of BNi-7 filler and pure Cu powders, and then them was used to braze 316L stainless steels with clearance of 40 μm. The effects of different pure Cu powder contents on microstructure and micro-hardness of brazed joints were studied. The results show that adding Cu powders into BNi-7 filler can improve the filling capability of brazed joint with large clearance effectively. Because of the addition of pure Cu powders, the brittle compounds in the brazing seam reduce significantly, and they are inlaid into the nickel based solid solution with the shapes of island, strip and point. All of these decrease the micro-hardness of brazed joints. The least brittle compounds were found in the brazed joint with pure Cu powders content of 9wt%, and the micro-hardness of the joint was 1 000 MPa.