To reduce energy consumption in the steel industry, increasing the ratio of scrap steel is essential. However, the residual element Cu leads to surface defects such as the star crack and transverse corner crack in continuously cast slabs deteriorating the performance of products. Thus, inspired by Guillemot et al. [Guillemot et al. Calphad 77:102429 (2022)], this paper developed a dendritic growth kinetic model for iron-based multi-component alloys in the directional solidification through coupling the solute cross-diffusion, constitutional undercooling, and marginal stability criterion at the solid-liquid (S/L) interface in consideration of the peritectic phase transformation. The thermodynamic database TCFE12 and the mobility database MOBFE7 in Thermo-Calc 2023b were invoked through the TQ interface to obtain thermodynamic data. The present work reveals the variations of dendrite growth kinetic parameters with the melt undercooling at different Cu contents in Fe-C-Si-Mn-P-Cu alloy system, particularly for low-carbon steel P590L, medium-carbon steel 37Mn, and high-carbon steel SWRH82B. The results indicate that as the melt undercooling (ΔT) increases, the tip growth velocity (Vtip) rises, and the tip radius (Rtip) initially decreases since the constitutional undercooling limit (Vc) but then increases near the absolute stability limit (Va). The increase in carbon content increases Va much more than Vc and thus expands the[Vc, Va] range. In contrast, an increase in Cu content does not significantly affect the[Vc, Va] range, but has a significant impact on the kinetic behavior at a given undercooling. A higher Cu content reduces the growth velocity and increases the dendrite tip radius. C and Cu have more pronounced impacts on the dendrite growth of low-carbon steel than other steels. As the Cu content increases, the solid and liquid concentrations of C, Si, P at S/L interface decrease, while Mn initially decreases and then increases. Peritectic phase transformation occurs in the solidification of 37Mn steel, altering the solidification interface from δ/L to γ/L. Thus, the liquidus slopes of C, Cu increase, while those of Si, Mn decrease at the phase transition point. An increase in Cu content promotes the enrichment of C, Si, and P in front of the solidification interface, while accelerating the depletion of Cu and Mn. Consequently, the segregation ratios of C, Si, and P increase gradually, while those of Cu and Mn decrease.

Influence of Residual Element Cu on Dendrite Growth Kinetics of Steel in Multi-Component System

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发表日期：

2025年4月7日

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Yinxing Guo,
Weiling Wang,
Sen Luo,
Yingying Yue,
Miaoyong Zhu

摘要

To reduce energy consumption in the steel industry, increasing the ratio of scrap steel is essential. However, the residual element Cu leads to surface defects such as the star crack and transverse corner crack in continuously cast slabs deteriorating the performance of products. Thus, inspired by Guillemot et al. [Guillemot et al. Calphad 77:102429 (2022)], this paper developed a dendritic growth kinetic model for iron-based multi-component alloys in the directional solidification through coupling the solute cross-diffusion, constitutional undercooling, and marginal stability criterion at the solid-liquid (S/L) interface in consideration of the peritectic phase transformation. The thermodynamic database TCFE12 and the mobility database MOBFE7 in Thermo-Calc 2023b were invoked through the TQ interface to obtain thermodynamic data. The present work reveals the variations of dendrite growth kinetic parameters with the melt undercooling at different Cu contents in Fe-C-Si-Mn-P-Cu alloy system, particularly for low-carbon steel P590L, medium-carbon steel 37Mn, and high-carbon steel SWRH82B. The results indicate that as the melt undercooling (ΔT) increases, the tip growth velocity (V_tip) rises, and the tip radius (R_tip) initially decreases since the constitutional undercooling limit (V_c) but then increases near the absolute stability limit (V_a). The increase in carbon content increases V_a much more than V_c and thus expands the[V_c, V_a] range. In contrast, an increase in Cu content does not significantly affect the[V_c, V_a] range, but has a significant impact on the kinetic behavior at a given undercooling. A higher Cu content reduces the growth velocity and increases the dendrite tip radius. C and Cu have more pronounced impacts on the dendrite growth of low-carbon steel than other steels. As the Cu content increases, the solid and liquid concentrations of C, Si, P at S/L interface decrease, while Mn initially decreases and then increases. Peritectic phase transformation occurs in the solidification of 37Mn steel, altering the solidification interface from δ/L to γ/L. Thus, the liquidus slopes of C, Cu increase, while those of Si, Mn decrease at the phase transition point. An increase in Cu content promotes the enrichment of C, Si, and P in front of the solidification interface, while accelerating the depletion of Cu and Mn. Consequently, the segregation ratios of C, Si, and P increase gradually, while those of Cu and Mn decrease.