RESEARCH AND DEVELOPMENT OF NEW FILLER MATERIALS FOR JOINING DIFFERENT MATERIALS BY ISOTHERMAL SOLIDIFICATION

为了开发一种熔点更低、结合强度更高的新型钎料，研制了几种由Cu-X合金和Cu-X-Y合金(X：Mn或Ag、Y：Fe、Cr或Al)制成的钎料，并将其应用于球墨铸铁与低碳钢的钎焊。无论填充金属的种类如何，合金相都在DCI侧析出，并通过等温凝固向钢侧长大。在使用铜-25%Mn钎料的情况下，DCI与钢的连接温度可在1223K以下进行，当DCI与钢的钎焊温度(1300K)比通常的铜钎焊温度降低约80K时，DCI与钢的连接强度可达到与纯铜钎焊相同的强度(约300 Mpa)。将铜-25%Mn钎料用于高铬铸铁与钢的钎焊时，合金相析出，结合强度可达220 Mpa左右。在1300K下将镍硬铸铁与钢进行钎焊，可获得300 Mpa左右的结合强度。观察了在铜-25%锰钎料中添加第三元素的效果。综合以上结果，可以认为，铜-25%锰合金是一种很有前途的低熔点铸铁与钢的焊料。

For the purpose of developing a new filler metal with lower melting point and giving higher bond-strength, several kind of filler metals made of Cu-X alloys and Cu-X-Y alloys (X : Mn or Ag, Y : Fe, Cr or Al) were produced and applied to brazing of a ductile cast iron (DCI) and a mild steel. Irrespective of the kind of filler metal, alloyed phases precipitated at the DCI side and grew toward the steel side by isothermal solidification. In case of using Cu-25% Mn filler metal, a DCI and a steel could be joined at lower temperature of 1223K, and the same bond-strength (about 300 MPa) as brazed with pure copper could be obtained when the DCI and steel was brazed at the temperature (1300 K) lowered by about 80K compared with the usual temperature of copper brazing. When the Cu-25% Mn filler metal was applied to brazing of a high chromium cast iron and a steel, alloyed phases precipitated and the bond-strength showed about 220 MPa. In case of brazing of a Ni-hard cast iron and a steel at 1300K, the bond-strength of about 300 MPa was obtained. The effects of addition of third element to Cu-25% Mn filler metal was observed. Based on the above results, it can be said that the Cu-25% Mn alloy is a promising filler metal with lower melting point for joining cast iron and steel.