Diffusion welding of hard alloys

Conclusions

• 1. The hot pressing method, which is characterized by induction heating in graphite dies, can be used for the diffusion welding of tungsten-cobalt hard alloys and the “baking-on” of new hard-alloy layers consisting of hard-alloy powder mixtures.

• 2. Mechanical tests have shown that the strength secured by means of diffusion welding at 1400° according to the proposed method approaches the strength of the monolithic hard alloy.

• 3. Diffusion welding in the presence of the liquid phase, which takes place under all investigated sets of conditions, promotes the development of a strong joint if the thermal cycle is short. The higher the process temperature, the greater the amount of the liquid phase in the hard alloy, the sooner and more readily the welding bridges appear, and the stronger the bond between the surfaces to be joined.

• 4. The use of nickel interlayers in the welding of hard alloys affects the process and the strength of the joint in the investigated temperature range, but to a lesser extent than the temperature. It is quite probable that the role of nickel buffer layers is much greater in the welding of hard alloys to steel, i.e., in the welding of materials with different characteristics at lower temperatures.