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，生产了几种由Cu-X合金和Cu-X-Y合金（X: Mn或Ag， Y: Fe， Cr或Al）制成的钎料，并应用于球墨铸铁（DCI）和低碳钢的钎焊。无论何种填充金属，合金相均在DCI侧析出，并通过等温凝固向钢侧生长。当钎料为Cu-25% Mn时，在1223K的较低温度下，DCI与钢的结合强度可达到与纯铜钎焊时相同（约300mpa），而在1300 K的钎焊温度下，DCI与钢的结合强度比铜的通常钎焊温度降低约80K。采用Cu-25% Mn钎料钎焊高铬铸铁和钢时，合金相析出，结合强度约为220 MPa。在1300K下钎焊镍硬铸铁与钢时，获得了约300mpa的结合强度。观察了在Cu-25% Mn填充金属中添加第三元素的效果。综上所述，Cu-25% Mn合金具有较低的熔点，是一种很有前途的铸铁与钢连接的填充金属。

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.