PROCEDURE FOR SURFACE HARDENING CYLINDER ITEMS OF HARDENABLE ALLOYS Russian patent published in 2011 - IPC C21D1/09 C21D9/28 

FIELD: metallurgy.

SUBSTANCE: surface of cylinder items of hardenable alloys is hardened with electric arc generated between non-consumable electrode and surface of item at relative transfer of arc and item. Also, the electrode is set at angle 160÷180° to vector of linear velocity of arc spot transfer at distance of 0.1÷0.5 of electric arc length from surface of an item and is transferred at velocity 500÷5500 mm/s. An end of non-consumable electrode is shaped as a cone with acute angle rounded at vertex. Angle of cone is equal to 30°÷40°, while rounded radius is equal to 0.3÷0.5 of electrode diameter. A conic section of the electrode is set parallel to vector of item velocity matching vertices of the conic sections of the electrode with a general point of item circumference and a straight line determined with vector of linear velocity of an item. There is established a hardening step equal to width of arc spot at hardening without cooling, and less, than width of arc spot at hardening with forced cooling. Hardening is carried out under a protective jacket.

EFFECT: manufacture of uniform hardened layer along thickness both in cross and lengthwise sections of shaft.

3 cl, 1 ex, 2 dwg