Аннотации:
This paper is devoted to theoretical analysis of the critical cooling rate necessary to suppress the diffusional transformation of austenite. The transition from isothermal conditions to continuous cooling conditions was accomplished in two ways: by means of the traditional integral of Scheil and Steinberg (often called the additivity rule), and via direct integration of the Avrami equation. The resulting equations for both the cooling rate and a coefficient in Grange and Kiefer's formula are presented. It was found that the theoretical value of the Grange-Kiefer coefficient almost never reached the value of 1.5 that they proposed. A method for determining the parameters in kinetic equations describing isothermal and continuous cooling transformations from an experimental time-temperature transformation diagram is also outlined. © 2013 by ASTM International.
