Abstract
Abstract We have studied the structure formation in the strengthened zone under high-temperature thermomechanical treatment and surface plasma quenching of carbon steel with a creation of a gradient-foliate structure under significant crushing of the surface layer. A diffusionless martensitic transformation develops in the surface zone. In the layers lying lower, austenite decays in a diffusive way with the formation of a sheet-like ferrite-carbide mixture with various degree of dispersion, which, if the cooling rate increases, results in enhancement of strength and deterioration of plastic characteristics of steel. It is noted that the formation in the surface layers of a gradient-foliated structure makes it possible to prevent a rapid transition from the martensite structure to troostite-martensite and mixed pearlite structures. This enhances contact-fatigue strength of steel and its crack resistance.