METHOD FOR THERMO-CHEMICAL TREATMENT OF STEEL PRODUCTS Russian patent published in 1996 - IPC

FIELD: thermo-chemical treatment of steel products. SUBSTANCE: method for thermo-chemical treatment of steel products includes carburizing of steel products in the saturating medium at the temperature higher than AC₃, with discrete surface interim cooling in each cycle down to 600-750 C and subsequent self-heating due to accumulation of heat and by repeating the cycles to reduce the temperature of product after self-heating below Ar₁. After discrete interim cooling of the surface, it is finally saturated in gas medium with carbon potential of 0.8-1.0 at the temperature of 920-960 C for 40-60 min, then, the product is compulsory cooled to below temperature Ar₁ and subjected to hardening from the repeated heating. When treating the products with thinner walls, discrete interim cooling of the surface with subsequent finish saturation is repeated to obtain the layer of the preset depth. EFFECT: higher efficiency. 3 tbl