Abstract: A piston ring preform is formed with a groove dividing its cylindrical outer surface, and this groove is filled up by plasma-spraying with a deposit of alloy whose surface is flush with the cylindrical outer surface of the preform not deposited with alloy. The alloy is about 55%-70% Cr, about 3%-9% C, and balance Fe. In preferred embodiments the groove has a bottom and side walls which are inclined at at least 100.degree. to one another, and a sub-layer composed of metal powder plasma-sprayed under the alloy deposit such that it adheres well to the bottom of the groove and which has good heat and oxidization resistance. The material of the preform may be cast iron, nodular graphite cast iron, or steel; and the material of the sub-layer may be a mixture of Ni and Al.