Investigation using 4D-CT of massive-like transformation from the δ to γ phase during and after δ-solidification in carbon steels

Joint 5th International Conference on Advances in Solidification Processes;5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining

土木建筑工程;计算机科学

Yasuda, Hideyuki^1 ; Hashimoto, Takahiro^1 ; Sei, Naoki^1 ; Morishita, Kohei^1 ; Yoshiya, Masato^2

Department of Materials Science and Engineering, Kyoto University, Sakyo, Kyoto

606-8501, Japan^1

Department of Adaptive Machine Systems, Osaka University, Suita, Osaka

565-0871, Japan^2

关键词: Crystallographic orientation relationships;    Delta-phase;    Direct observations;    Liquid phasis;    Metallic alloys;    Peritectic reaction;    Time-resolved;    Volume change;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/529/1/012013/pdf
DOI  :  10.1088/1757-899X/529/1/012013

来源: IOP

【 摘 要 】

For a long time, the γ phase in metallic alloys has seemed to be produced through a peritectic reaction between the δ and liquid phases. However, direct observations have shown that a massive-like transformation, in which the δ phase transforms into the γ phase in the solid state, is dominant during or after solidification of the δ phase in carbon steels. To characterize such massive-like transformation, we use time-resolved tomography (4D-CT) to demonstrate the volume change during cooling from the melt and the crystallographic orientation relationship between the δ and γ phases. The volume changes from solidification and from the massive-like transformation from the δ to the γ phase were -3% and -0.5%, respectively. The transformation from the δ to the γ phase finished quickly, as demonstrated by the volume change. Fine γ grains were produced even in a single δ grain through the massive-like transformation. Also, the refined γ grains showed a wide crystallographic distribution.