METHOD OF AERODYNAMIC HARDENING OF ITEMS Russian patent published in 2015 - IPC C21D8/00 C21D9/22 

FIELD: machine building.

SUBSTANCE: treatment is performed by two hardening cycles, each of them contains heating to temperature equal to 10-30% of item melting temperature, and holding for time period at least 1.6 minute per 1 mm of maximum size of hardened item, further aerodynamic action of sound frequency oscillations within range 160-800 Hz for time period equal to 30-40% of holding time during first hardening cycle and 20-30% of holding time during the second hardening cycle by air under pressure during each cycle within range from 1.5 bar to 2.0 bar with hour air consumption during the first cycle 2.5-2.9 m³ and increased by 70-80% air hour consumption during the second cycle in comparison with the first cycle, then two ageing cycles at 150-170°C are performed for time period equal to the holding time, with further air cooling until complete cooling.

EFFECT: increased impact strength upon simultaneous keeping of initial high hardness and wear resistance of items, increased process stability.

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