METHOD OF SURFACE HARDENING OF STEEL PARTS Russian patent published in 2009 - IPC B23H9/00 C23C4/12 

FIELD: process engineering.

SUBSTANCE: revolving steel part is subjected to arc-discharge constant current, in conditions of high-voltage self-restoring electric discharge, in active service medium arranged between processed part and electrode, both connected to high-voltage constant current source. Service medium is represented by water fed in jets from the electrode end face, the jet diametre making 1.0 to 3.0 mm and feed rate making 0.1 to 20 m/s. Note here that electric arc discharges are self-generated along water jet, discharge density making 6 to 25 per 1 mm and electrode-cathode running at 5 to 20 m/s. Electric arc discharge effects are brought about locally, the discharge being directed at 90° to processed part to flash off the part working surface, from 4 to 6 mm distance. Aforesaid surface represents 300 mcm-deep cones with the base diametre making 0.2 to 0.5 mm. Surface layer features uniformly distributed alternating structure of base metal and multiple cone-like penetrations with changed fine-crystalline structure. Thereafter, mechanical processing is carried out.

EFFECT: higher surface toughness, hardness, strength and wear resistance.

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