In Situ Observation and Phase-Field Modeling of Peritectic Solidification of Low-Carbon Steel
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AS we know, steel is a world-widely used metallic alloy, because of superior mechanical and physical properties and competitive price. In the casting process of steels with carbon content ranging from 0.09 to 0.53 wt pct, the primary crystal phase of d-ferrite reacts with residual liquid (L) to produce a secondary crystal phase of c-austenite by peritectic solidification, which is one of the most commonly observed phenomena in practical metallic alloys.[1,2] Owing to the significant physical property difference between the c-austenite and d-ferrite, peritectic solidification induces large shrinkage of solidified shell, which is extremely prone to cause remarkable crack formation, even breakout, during the continuous casting of practical peritectic steel.[3,4] Consequently, peritectic solidification plays an important
SEN LUO, GUANGGUANG LIU, PENG WANG, WEILING WANG, and MIAOYONG ZHU are with the Key Laboratory for Ecological Metallurgy of Multimetallic Ores (Ministry of Education), Northeastern University, Shenyang 110819, Liaoning, China and also with the School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China. Contact e-mail: [email protected] XIAOHUA WANG is with the College of Chemistry, Chemical Engineering and Environmental Engineering, Liaoning Shihua University, Fushun 113001, Liaoning, China. Manuscript submitted September 2, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS A
role in the determination of steel quality and has attracted a lot of attention. According to the definition for peritectic solidification introduced by Kerr et al.,[5] the peritectic reaction (L + d fi c) occurs firstly, where c-austenite grows along the d/L interfacial boundary and finally separates the liquid and d-ferrite, followed by peritectic transformation (L fi c and d fi c), where c-austenite grows into liquid and d-ferrite. Extensive researches[6–9] have been conducted to study the behavior and mechanism of the peritectic solidification, and a notable distinction between the peritectic reaction and peritectic transformation was emphasized in the past few decades. Fredriksson and Nyle´n[10] performed a unidirectional solidification experiment and simple analytic calculation to study on the solidification process of alloys in peritectic systems and suggested that the advancing rate of the secondary phase along the liquid/primary phase interface is controlled by the concentration difference. Matsuura et al.[2] performed experiments with a diffusion couple of Fe-C alloy melt and d-Fe, and concluded that the peritectic reaction in the iron-carbon system is controlled by the diffusion of carbon. Shibata et al.[11] first performed in situ dynamic observations of the peritectic solidification of Fe-C alloys using the high-temperature laser-scanning confocal microscopy (HTLSCM) and concluded that the peritectic reaction is not controlled by diffusion of carbon but by either a massive transformation or solidification of c phase direct from the liquid.
However, the theoretical framework was unable to be established to explai
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