DIFFUSION MODEL OF TRANSFORMATION OF AUSTENITE IN CARBON STEELS

In the carbon steel transformation kinetics of austenite, except martensitic transformation, in many ways determined by the diffusion of carbon, which allows them to be attributed to the transformations controlled by diffusion. The purpose - to provide an overview of the diffusion model developed by the authors of the decomposition of austenite in comparison with the previously existing models. Zeener has offered a ratio between between-plates distance and size of overcooling of steel S0 ~ ΔT-1. The experimental results show, however, that the measured meanings of between-plates distance of perlite much more those meanings, which are given by model Zeener. The authors find temperature dependence of between-plates distance of perlite from size of overcooling of an alloy as S0 ~ , precisely enough appropriate to experimental data. Important by the kinetic characteristic of process the transformation of austenite is the growth rate of perlite v. The size of growth rate was received Меhl as: v = КS0-1.In the subsequent works the scientists find the various decisions of the equation the diffusion of carbon in austenite, allowing to define size of factor K and to take into account influence of the additional factors - structural pressure (B. Ljubov), quantity of not metal inclusions (V. Olschanetskij), that raises аccuracy of accounts. Conclusion. Developed by the authors diffusion model of faltering transformation austenite in iron-carbon alloys has allowed to explain formation of perlite and beinitе in the interval of temperatures. Became theoretically found temperature dependence of growth rate of ?-phase on size of overcooling as v ~ .