V.G. Efremenko, V.I. Zurnadgy

The article provides an overview of foreign publications on the influence of modes Q&P (quenching and partitioning) heat treatment on mechanical and operational properties of structural steels with different carbon content. The mechanism of structure formation in Q&P-treated steels is analyzed, it is shown that Q&P-treatment results in formation of a microstructure containing tempered martensite, lower bainite (polygonal ferrite) with an increased amount of residual austenite which provides TRIP-effect when loaded. The values of strength and plastic properties, achieved in the low-carbon, medium-and high-carbon steel as a result of Q&P-processing are presented. The effect of alloying elements (Mn, Si, Al, Cr, Mo, Nb etc.) on the properties of the Q&P-steels is described. It is shown the crucial role of silicon and aluminum in formation of residual austenite and carbides-free bainite. The parameters of Q&P-processing, determining the amount of residual austenite and its ability to deformation martensite transformation during deformation are analyzed. The classification of types Q&P-treatment, depending on the additional operations of heat treatment such as preliminary hardening, heating in the intercritical temperature range, tempering for dispersed carbides precipitation, is given. The prospects of Q&P-processing to produce relatively inexpensive high strength steels are described