以B-Ag40CuZnCdNi合金为钎料, 采用火焰钎焊方法实现了QT500-7铸铁的连接。研究了“三明治”法和毛细法两种钎料放置方式及不同加热时间对钎焊接头抗剪强度的影响, 并对连接界面的微观组织进行了分析。结果表明: 用“三明治”法放置钎料时, 接头容易产生焊接缺陷, 接头的承载能力低于母材; 用毛细法放置钎料时, 在足够长的加热时间条件下, 液态钎料的填缝过程同时具有清洁钎缝间隙的作用, 有利于得到钎缝细小平直且缺陷少的接头, 因此抗剪强度得到提高, 加热时间大于5 min时, 接头承载能力高于母材, 但加热时间不足时反而不如“三明治”法的施焊效果。

Using B-Ag40CuZnCdNi alloy as filler metal, cast iron QT500-7 was connected by torch brazing. The effect of filler metal placement method and heating time on the shear strength of the brazed joints was studied by shear test and microstructure observation. The results showed that when sandwich method was used to place the filler metal, the joint was likely to cause welding defects, and the carrying capacity of the joint was lower than that of base metal. When capillary method was used in enough heating time, the filling process of the liquid metal had also played a role of cleaning the gap of brazing seam, which was helpful to get the joint with thin and straight brazing seam and less defects, so the shear strength had been improved, when the heating time was more than 5 min, the carrying capacity of the joint was higher than that of base metal, but it will be not as good as sandwich method if the heating time was insufficient.