Numerical Analysis on Crack Generation Behavior of Hypo Peritectic Steel in Continuous Casting Process
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Numerical Analysis on Crack Generation Behavior of Hypo Peritectic Steel in Continuous Casting Process Jun‑hyun Jo1 · Min‑seok Park2 · Kyung‑woo Yi1,3 Received: 4 June 2020 / Accepted: 2 September 2020 © The Korean Institute of Metals and Materials 2020
Abstract Hypo peritectic steels exhibit a high possibility of longitudinal crack during continuous casting. Therefore, many researchers have studied the mechanisms of crack generation in hypo peritectic steel. Stress in solidified shell, or volume contraction with small liquid fractions were suggested as the mechanisms of crack generation. A new model was developed for predicting possibility of crack generation by calculating strain rates in solid, volume contraction rate during solidification, and the probability of liquid unfilling in continuous cooling processes. The results show that massive transformation from the δ phase to the γ phase, and peritectic transformation during solidification can be the main crack generation mechanisms. Furthermore, a linear relationship exists between the amount of undercooling for peritectic transformation ( dTp) and the carbon content of the boundary for dividing the two crack generation mechanisms. Additionally, the longitudinal crack ratios of the field results are analyzed through strain rates in solid and liquid unfilling possibilities. Relative positions in the range of hypo peritectic steel and effective carbon contents are suggested to analyze the crack ratio of steels with alloying elements. This analysis shows that the results obtained from the new models for crack generation possibility are usable, and dTp can generate the behavioral differences in crack generation according to the conditions. Keywords Hypo peritectic steel · Modeling · Possibility of crack generation · Strain rate · Volume contraction
1 Introduction Longitudinal crack generation on solidified slab surfaces is one of the major problems experienced in continuous casting processed. Especially, hypo-peritectic steels with approximately 0.09–0.16 wt% carbon are known to show high crack generation ratios [1, 2]. This phenomenon is generally believed to be influenced by peritectic transformation, as well as the solidification of the γ phase at the interface of the δ and L phases, at the early stage of continuous casting. Large volume changes by peritectic solidification and cooling may lead to the local deformation of the solidified shell, resulting in uneven heat transfer in the mold or stress * Kyung‑woo Yi [email protected] 1
Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic Of Korea
2
Technical Research Laboratories, POSCO, Kwangyang 57807, Republic Of Korea
3
Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic Of Korea
generation on the shell surface, thereby causing cracks on the cast shell surface [2]. However, the exact mechanisms of surface cracks remain controversial. Many researchers have suggested various crack generation mechanisms on the sh
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