Surface heat treatment of piston rings

A piston ring comprising:

• a base material forming a ring, said base material having a predetermined radial portion that is selectively transformable between three material phases, said second material phase harder than said first material phase and said third material phase harder than said first and second material phases wherein a first thickness of said base material is transformed from said first material phase to said third material phase by at least one of repetitively superficially heating said base material and cooling said predetermined radial portion of said base material.

A method of superficially and selectively heat treating a piston ring, comprising:

• fabricating the piston ring from a base material wherein a predetermined portion of a radial outer surface of the ring is selectively transformable between at least two material phases, a second material phase being harder than a first material phase;
• superficially heating said predetermined portion of said base material;
• and cooling said predetermined portion, wherein said material phase of said predetermined portion is transformed from said first material phase to said second material phase, wherein said first material phase is a course martensitic material, and said second material phase is a fine martensitic material of wherein said first material phase is an austenitic material, and said second phase is martensitic material.