On the Mechanism of Bainite Transformation and the Qauality of Thermal Hardening of Structural Bainitic Steels
摘要
This article provides a brief analysis of recent studies on the bainitic transformation mechanism and presents experimental results obtained by the authors during bainitic hardening of structural steels. It is emphasized that despite numerous studies, the bainitic transformation mechanism remains poorly understood. The mechanism of transformation from an FCC lattice to a BCC lattice, the role of carbon diffusion leading to its redistribution and the formation of carbon-supersaturated ferrite, and the processes of carbide precipitation remain unclear. Bainite provides high-quality mechanical properties, such as: strength, ductility, and toughness. Compared to pearlite, sorbite, and troostite, lower bainite exhibits higher hardness and strength with high ductility and toughness. This is explained by the increased carbon content in ferrite and the higher dislocation density in bainite, as well as the formation of dispersed carbides.