異種材のろう付における母材の溶解-晶出とその応用(第6報) : 鉄とMO, Wの銅ろう付におけるNiメッキの効果

概要

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Mo and W, which have excellent high temperature properties, are often brazed to Fe for extended use. However, the direct brazing of Fe to Mo or W tends to cause the exfoliation of the brazed joint in service. In order to eliminate this defect, the Ni plating on the Fe base metal prior to brazing has been practiced in industry. This paper clarifies the effect of Ni plating on Cu brazing of low C steel to Mo or W. It also examines the shear strength of the brazed joints. In the case of no plating, the low C steel base mteal dissolves into molten Cu filler metal and, simultaneously, the dissolved low C iron deposits as a plate-like Fe-Mo-Cu or Fe-W-Cu alloy phase from the Mo or W base metal at a constant brazing temperature-that is, a "dissolution and deposit of base metal" takes place. Since Fe of the deposited phase penetrates into the Mo or W base metal, an intermetallic compound phase Fe_7Mo_6 or Fe_7W_6,which is inherently brittle, is formed at that base metal boundary. The Ni plating of 1.1 to 4.3 μm thickness on the low C steel base metal to be joined restrains the dissolution and deposit of base metal ; it also improves the mechanical properties of both deposited and intermetallic compound phases by alloying with Ni. The shear strength of the brazed joint is thereby improved.
社団法人溶接学会の論文
1984-05-05