METHOD OF HARDENING OF STEEL PARTS Russian patent published in 1999 - IPC

FIELD: metallurgy; applicable in hardening of machine parts by method of cold plastic deformation for operation under conditions of friction and cyclic loads. SUBSTANCE: method includes prior to finishing thermo-chemical treatment - ionic nitriding, performance of prerecrystallization stabilizing annealing at temperatures exceeding temperature of maximum deformation ageing for the given steel grade by 80-120 C. This is made to preserve deformation hardening produced in material of part during cold plastic deformation. Such intermediate annealing ensures higher resistance of deformed steel to recrystallization in repeated heating. The method allows preservation of considerable part of metal deformation hardening in nitriding after annealing to increase strength properties of part core by 25-50% without appreciable reduction of ductility, and improved cyclic strength of finished article. EFFECT: higher efficiency. 1 dwg, 2 tbl