METHOD FOR SURFACE TREATMENT OF HEAT-RESISTANT STAINLESS STEEL Russian patent published in 2023 - IPC C23C8/26 C23C8/02 C21D1/18 C23G1/08 

FIELD: steel processing.

SUBSTANCE: methods for chemical-thermal treatment of steel, namely, methods for depassivation of steel surfaceб to be used when hardening steel in vacuum furnaces. The method includes preparation and depassivation of the surface of the part, during preparation the surface of the part is cleaned from contamination, and depassivation is carried out in the following stages: 1) heat treatment of the part in a vacuum hardening furnace by heating; 2) exposure of the part until it is completely warmed up; 3) cooling of the part in nitrogen or argon; 4) the part is transferred to a vacuum chemical-thermal treatment furnace for 30 minutes; 5) additional oxidation, including heating the part in nitrogen to a temperature of 500°C, residual pressure in the furnace chamber at 0.3 bar; 6) after equalizing the temperature of the part, replacing nitrogen in the furnace chamber with nitrous oxide and exposing for two hours; 7) restoration of the surface of the part, including the replacement of nitrous oxide with ammonia in the furnace chamber; 8) repetition of steps five through seven; 9) nitriding without removing the part from the furnace in which the oxidation was carried out.

EFFECT: better adapted steel surface for further nitriding.

2 cl, 1 dwg, 11 tbl