Prediction Model for Degree of Solid-shell Unevenness during Initial Solidification in the Mold

• Published in: ISIJ International 2021/10/15, Vol.61(10), pp.2534-2539
• Main Authors: Kwon, Sang-Hum, Won, Young-Mok, Back, Gu Seul, Kim, Hyeju, Lee, Jae Sang, Kim, Dong-Gyu, Heo, Yoon Uk, Yim, Chang Hee
• Format: Article
• Language: English
• Subjects: continuous casting; heat flux; phase transformation; solid-shell unevenness; surface quality
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.ISIJINT-2021-155

The unevenness of the solid-shell and heat flux (Φq) during solidification were measured for various steel grades with casting apparatus. Then the data were used to develop a model to predict the degree of solid-shell unevenness according to the steel composition. The surface of the solid-shell was the least uniform when the steel composition was near the peritectic point, at which Φq was the lowest. A model to calculate an index of solid-shell unevenness was developed under the following conditions. Solid-shell unevenness is formed at the initial solidification under the constant cooling rate, which occurs only where solid fraction (fs) is from 0.9 to 1.0. In addition, solid-shell unevenness is proportional to the amount of phase transformation and inversely proportional to the temperature range of ΔTPT; between the temperature of fs = 0.9 and the solidus temperature. This model shows about 87% of the prediction accuracy in the experimental results of this study and also gives reasonable explanations of solid-shell unevenness observed in previous researches on steels.