Furnace brazing type 304 stainless steel to vanadium alloy (V-5Cr-5Ti)

In this investigation, pure copper was joined to type 304 stainless steel and V-5Cr-5Ti by brazing in a high vacuum furnace. Microstructural changes in the brazed region and surrounding substrates were examined as a function of holding time at temperatures of 20 degreesC, 40 degreesC and 60 degreesC above the melting point of copper. Reaction layers, which were extremely brittle, formed between the Cu and V-5Cr-5Ti substrates. The formation of intermetallic phases at the filler metal/substrate interfaces was evaluated. Additionally, precipitates (FeCu2 and FeCu18) formed in the Cu rich filler region. For temperatures greater than or equal to 60 degreesC above the melting point of Cu, extensive transverse cracking was observed. Hardness tests substantiated the hypothesis that the Cu/V-5Cr-5Ti reaction layer was extremely brittle, since micro-cracks propagated from the tips of the diamond-shaped indentations. Results of mechanical properties tests of the brazed material are also presented. (C) 2000 Elsevier Science B.V. All rights reserved.