METHOD FOR LOW-TEMPERATURE CEMENTATION (LTC) OF STEEL Russian patent published in 2019 - IPC C23C8/66 C23C8/80 

FIELD: technological processes.

SUBSTANCE: invention relates to chemical-thermal treatment, namely to cementation processes, and can be used in machine building, automotive industry and other industries for surface hardening of parts made from low-carbon structural steels. Method of steel parts carburizing includes heating of parts in carburizer to temperature equal to or higher than Ac₃, with holding at said temperature and cooling. Holding at temperature higher than Ac₃ is carried out until complete austenitic conversion, and cooling – to the temperature of polymorphic conversion from the range of [(Ar₃+50)…(Ar₁-50)] °C is cured at said temperature for 1 to 3.5 hours. In particular cases of invention implementation at cooling of alloyed steels values of critical points Ar₃ and Ar₁ correspond to alloyed steels. When cooling low-carbon steels with carbon content of up to 0.25 %, critical points Ar₃ and Ar₁ correspond to values of critical points of high carbon non-alloy steels with carbon content of 0.6–1.0 %.

EFFECT: obtaining on steel parts a surface layer having high hardness and wear resistance, shorter duration of diffusion saturation, creation of favorable distribution of hardness over depth of layer, which contributes to increase of fatigue limit of material, and improvement of quality of cemented layer and transition zone.

3 cl, 7 dwg