Principles of Design of the Chemical Composition of Steels for Forming a Structure of Lower Carbide-Free Bainite Under Delayed Cooling

Phase and structural transformations in structural steels are studied by the methods of dilatometric analysis and light, scanning and transmission microscopy. Thermokinetic diagrams of decomposition of supercooled austenite are plotted. Principal possibility of formation of a structure of lower carbide-free bainite by delayed continuous cooling is demonstrated for steels of two alloying systems, namely, Kh3G3MFS and KhN3MFS containing 0.25 – 0.30 and 0.40 – 0.45% C. Principal approaches to obtaining a chemical composition of lower carbide-free bainite in structural steels are formulated.