METHOD OF CARBONITRIDING PARTS MADE FROM STRUCTURAL AND TOOL STEELS Russian patent published in 2016 - IPC C23C8/76 

FIELD: technological processes.

SUBSTANCE: invention relates to chemical-thermal treatment of structural and tool steel and can be used for surface strengthening of parts of machines and tools in machine building, metallurgy, chemical and tool industry. Method of carbonitriding parts comprises preparation of paste by mixing potassium ferricyanide K₄Fe(CN)₆, carbon black DG-100, carbamide, bentonite, marshalite and paste-forming liquid in following proportions, wt%: potassium ferricyanide K₄Fe(CN)₆ - 16, carbamide (NH₂)₂CO - 18, bentonite - 12, marshallite - 24, carbon black DG-100 - balance, paste-forming liquid (vol%): polyvinyl acetate emulsion 50 %, ethanol - 10 %, water - 40 %, application of paste on parts, heating in neutral salt bath at following ratio of components, wt%: NaCl - 35, Na₂CO₃ - 35, NaOH - 30, at a temperature of 550-650 °C with holding at this temperature for 0.5-3 hours. Then part is cooled in oil and low-temperature tempering at temperature 150-200 °C is carried out.

EFFECT: higher speed of carbonitriding and reduced labour input, wider temperature range, increased uniformity of heating of parts and high environmental safety.

1 cl, 1 ex