introduction

Before 1986 piston rings for VAZ engines were manufactured by the Michurinsk Plant of Automatic Equipment. Upper compression rings were produced from high-strength cast iron with spheroidal graphite, and oil-control rings and lower compression rings were produced from gray cast iron. In both cases individual preforms were used for each ring. The central zone of the cross section of upper compression rings often exhibited a streak loose shrinkage structure. The structure of the rings was nonuniform with a variable content of ledeburite, pearlite, and ferrite. The structure of oil-control and lower compression rings contained coarse rosette graphite and often an elevated amount of ferrite. Thus, the rings had unstable micro- and macrostructures and mechanical properties. Over 20% of the cast preforms did not correspond to the standard requirements on the quality of the material and the parts. The use of such piston rings caused scoring, increased the consumption of oil, and ultimately decreased the service life of the parts.