| Title |
Tranformations : Effect of Austenite Undercooling on Dynamic Ferrite Transformation |
| Authors |
홍승찬(Seung Chan Hong),임성환(Sung Hwan Lim),이경종(Kyung Jong Lee),이경섭(Kyung Sub Lee) |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Abstract |
Hot compression test was performed to examine the effect of degree of undercooling on dynamic ferrite transformation behavior. Austenite undercooling was controlled by cooling rate from austenitization temperature to deformation temperature. The degree of undercooling was determined as ΔT (=Ae_3 - Ar_3). Ae_3 temperature was calculated by using Thermo-Calc and Ar_3 temperature was measured by dilatometry. The fine grained ferrite was formed during 70% deformation just above Ar_3 temperature. It was observed that the average ferrite grain size was 2 ㎛ regardless of temperature. At this temperature the flow stress was decreased by ferrite formation during deformation. The amount of ferrite transformed dynamically was increased as ΔT was increased. While, the ferrite grain size was mainly influenced by the amount of deformation. It was also confirmed that the critical strain of dynamic ferrite at high cooling rate to deformation temperature was shifted to lower strain compared to that at low cooling rate with the aid of increasing undercooling. |