When selecting filler metal, the characteristics of the base material and the requirements for joint performance are mainly considered. Generally speaking, the following factors should be considered comprehensively:

1. The filler metal should have a suitable melting temperature range, at least tens of degrees lower than the melting temperature range of the base metal.

2. At the brazing temperature, it should have good wettability to ensure that the gap between the brazing seams is fully filled.

3. The filler metal and the base material should have a diffusion effect to form a firm bond.

4. The brazed joint obtained should meet the technical requirements of the product and meet the requirements of mechanical properties, physical and chemical properties, and performance.