Method of forming fine grains of co-cr-mo alloy with nitrogen addition and co-cr-mo alloy with nitrogen addition

A method of forming fine grains of a Co—Cr—Mo alloy with nitrogen addition, comprising:

• subjecting a Co—Cr—Mo alloy with nitrogen addition composed of 26 to 35% by weight of Cr, 2 to 8% by weight of Mo, 0.1 to 0.3% by weight of N, and balance of Co to solution treatment;
• subjecting the alloy to isothermal aging treatment holding the alloy at 670 to 830° C. for a predetermined period of time to form a multi-phase structure composed of an ε-phase and a Cr nitride by means of an isothermal aging treatment;
• cooling the alloy;
• and
• subjecting the alloy to reverse transformation treatment in which the alloy is heated at a temperature range of 870 to 1100° C. for reverse transformation to a single γ-phase from the multi-phase structure composed of an ε-phase and a Cr nitride.