CARBONITRIDING OF PARTS FROM DIE STEELS Russian patent published in 2016 - IPC C23C8/76 

FIELD: metallurgy.

SUBSTANCE: method of carbonitriding of parts from die steels includes paste preparation by mixing of ferricyanide potassium K₄Fe(CN)₆ and gaseous soot DG-100, paste application to the product, heating with holding, cooling in oil and low-temperature tempering. During paste preparation bentonite and marshallite are additionally added at the following ratio, wt %: ferricyanide potassium K₄Fe(CN)₆ - 24-34, bentonite - 12, marshallite - 24, gaseous soot DG-100 - rest, and polacryl made out of glue PVA (GOST 18992-80) - 50%, methanol or ethanol - 10% and water - 40% is made as paste-forming agent. Heating is performed in neutral salt bath at the following ratio of components, wt %: NaCl-50, Na₂CO₃-40, NaOH-10, at 600-750°C with holding at this temperature for 0.5-3 hours. Then samples are oil cooled, and low temperature tempering at temperature 150-200°C is performed.

EFFECT: increased speed of carbonitriding and reduced labour intensity of the process, extension of temperature range, increased uniformity of parts heating, and increased ecological safety.

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