| Title |
An Application of the Johnson-Mehl-Avrami-Kolmogorov Equation to Austenite to Ferrite Transformation Kinetics |
| Authors |
한흥남(Heung Nam Han); 이재곤(Jae Kon Lee) |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
JMAK equation; Phase transformation; Additivity rule; Carbon enrichment |
| Abstract |
During the austenite to ferrite transformation in hypoeutectoid steel, and application of the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation without the adoption of the equilibrium ferrite fraction is suggested to describe the isothermal phase transformation in the temperature range between Ae_3 and Ae_1. The suggestion is based on the carbon enrichment in the untransformed austenite during transformation, which can prevent the ferrite fraction getting over the equilibrium fraction. Even under isothermal condition, the additivity concept should be used to take the change of the state variables in JMAK equation into account due to the carbon enrichment. The phase transformation kinetics under various isothermal conditions between Ae_3 and Ae_1 was calculated using the method and the calculated results were compared with the experimental data measured by a transformation dilatometer. The phase transformation for non-isothermal conditions was also described on the basis of the JMAK equation. The austenite to ferrite transformation kinetics of the steels could be well described by the suggested method. |