Yu. N. Griboedov’s scientific contributions

1.Chemical analysis of carburized foil 0.25 mm thick of steel 20Kh2N4A showed that with heating to quenching temperature for 2 h in air the average carbon concentration decreases from 1.23 to 0.4%, while the oxygen concentration increases from 0.14 to 0.4%. The addition of ammonia to the mixture of endothermal gas with natural gas led to a concentration of 0.3% N in the foil and lowered the microhardness (to H100=600).2.To prevent decarburizing and oxidation of the surface zones of steel 20Kh2N4A, leading to premature wear and failure, the steel should be heated in hydrocarbon gases, with ammonia in some cases.

1. The use of preliminary carburizing for steels 4Kh5MFS, 4Kh2M1FN, and 4Kh5V2FS results in a layer of chromium carbide 30–50% deeper after chromizing, and also a higher surface hardness after quenching and tempering. 2. Preliminary carburizing improves the heat resistance, red hardness, and hot wear as compared with diffusion chromizing (without carburizing) or standard heat treatment. 3. Production tests of mandrels and matrixes of cable presses made of steels 4Kh5MFS and 4Kh2M1FN indicate that after the combination treatment the durability is three to four times higher than that of tools made of steel 3Kh2V8F subjected to standard heat treatment.