Characteristic features of the boriding of tool steel 4Kh5MFS from the gas phase

Conclusions

• 1. The process of boriding steel 4Kh5MFS from the gas phase using powder mixtures takes place in a stable and uniform manner, but oxidation of the surface metal is possible due to the presence of oxygen. Significant variation in the composition of the diffusion layer occurs in this case. The redistribution of chromium, silicon, and vanadium is observed; the concentration of molybdenum is virtually unchanged.

• 2. To eliminate the formation of a zone impoverished of alloying elements, it is expedient to use steels with an elevated content of such alloying elements as tungsten, molybdenum, and vanadium for molds subjected to surface hardening by boriding.

• 3. The boriding of tool steel from powder mixtures ensures the formation of boride layers 30–35 μm thick, which exhibit high thermal stability under cyclic temperatures and force effects; this is the premise for increasing, the stability of molds, which are taken out of service primarily because of bearing stress, plastic forming, and the sticking of molten metal.