Applications of vacuum brazing

---

YG8 is a tungsten-cobalt material. WC-Co-based cemented carbide has high hardness, wear resistance, good thermal hardness and thermal conductivity, but its impact is low and the market price is expensive. It needs to be connected with steel to exert its excellent comprehensive performance. 0Cr13 ferritic stainless steel has high corrosion resistance, and the connection with YG8 hard alloy can be used in corrosive media.

However, there is a huge difference in the linear expansion coefficient between the two materials. The linear expansion coefficient of cemented carbide is generally only 1/3~1/2 of ferrite stainless steel. During the cooling process of vacuum brazing, due to the large shrinkage of the steel side As a result, a large tensile stress is formed on the cemented carbide side, resulting in poor joint performance. At the same time, since Cr13 steel contains 13Cr, it is easy to form Cr₂O₃ oxide film on its surface, and form chromium compounds during vacuum brazing cooling, which brings difficulties to vacuum brazing.

Vacuum Brazing Process

The welding method is usually vacuum brazing, and the vacuum degree is above 0.007Pa; the solder is generally CuMnCo solder, and its mass fraction is: 86~88%Cu; 9.5~10.5%Mn; 2.5~3.5%Co. The vacuum brazing temperature is about 991°C~1100°C.

The test shows that CuMnCo solder has good wettability to YG8 cemented carbide and 0Cr13 stainless steel, and the wettability on 0Cr13 steel is better than that of YG8 cemented carbide at various brazing temperatures. The welding temperature is 1070°C to obtain the best welded joint with mechanical properties, and an appropriate amount of Fe-Co-based solid solution is produced in the two interface reaction zones of the brazing seam structure, and a uniform and plastic Cu-Mn-based solid solution is formed in the central area of the fiber seam. solid solution. At the optimal brazing temperature, the joint obtained when the brazing seam gap is 0.20m has the highest bending strength of 445MPa.

The RHVB series furnaces produced by SIMUWU Vacuum Technology can meet the brazing requirements of such products.

Learn More:

Vacuum carburizing of aviation gear steel

MIM degreasing and sintering for ceramic hard alloy

Study on Vacuum Brazing Technology of Silver-Cu-Based Solder