卷渣類夾雜物在結晶器鋼液中成分轉變的動力學模型

王舉金; 張立峰; 陳威; 王勝東; 張月鑫; 任英

doi:10.13374/j.issn2095-9389.2020.04.13.003

卷渣類夾雜物在結晶器鋼液中成分轉變的動力學模型

doi: 10.13374/j.issn2095-9389.2020.04.13.003

王舉金¹,
張立峰^{1, 2, ,},
陳威¹,
王勝東^{1, 3},
張月鑫¹,
任英¹

1.
北京科技大學冶金與生態工程學院，北京 100083
2.
燕山大學亞穩材料制備技術與科學國家重點實驗室，秦皇島 066044
3.
首鋼京唐鋼鐵聯合有限責任公司煉鋼部，唐山 063200

基金項目: 國家自然科學基金資助項目（U1860206，51725402，51874032）

詳細信息

通訊作者:
E-mail：zhanglifeng@ysu.edu.cn

中圖分類號: TF777.1
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出版歷程
- 收稿日期: 2020-04-13
- 刊出日期: 2021-06-25

Kinetic model of the composition transformation of slag inclusions in molten steel in continuous casting mold

1.
School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
2.
State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
3.
Steelmaking Department, Shougang Jingtang United Iron & Steel Co., Ltd., Tangshan 063200, China

More Information

Corresponding author: E-mail: zhanglifeng@ysu.edu.cn

摘要

摘要: 國內某廠鍍錫板缺陷處夾雜物主要來自結晶器保護渣的卷入，但其成分與結晶器保護渣有明顯差別。為了進一步研究這種成分差別的原因，建立了耦合熱力學平衡和動力學擴散的結晶器卷渣類夾雜物的成分轉變動力學模型，明確了卷渣類夾雜物的尺寸和密度對其成分轉變的影響規律，并通過對結晶器和液相穴內的鋼液流動和夾雜物運動的數值模擬研究了夾雜物在鋼液中的停留時間。結果表明：結晶器保護渣卷入鋼液后與鋼液不斷發生反應，成分會發生明顯改變。卷渣類夾雜物轉變為缺陷處夾雜物所需要的時間與夾雜物尺寸以及夾雜物密度有關，夾雜物的尺寸和密度越大，轉變為缺陷處夾雜物成分所需的時間越長。卷渣類夾雜物轉變為缺陷處夾雜物所需時間與夾雜物尺寸呈冪函數關系，與夾雜物密度呈二次函數關系。夾雜物在鋼液中的平均停留時間隨夾雜物直徑的增大而減小，并且隨著拉速的增大而減小。小尺寸夾雜物一旦被卷入鋼液中，將有充足的時間轉變為缺陷處的成分。大尺寸夾雜物在鋼液中的平均停留時間小于成分轉變時間，但最大停留時間遠大于成分轉變所需時間，表明部分大尺寸夾雜物依然具有充足的停留時間轉變為缺陷處的成分。
- 卷渣類夾雜物 /
- 動力學模型 /
- 結晶器保護渣 /
- 線狀缺陷 /
- 鍍錫板
Abstract: The inclusions at the defects of tinplate originated from the entrainment of the mold flux, but their composition differed significantly from that of the mold flux. To investigate this difference, a kinetic model was established of the transformation of the composition of the slag inclusions, coupled with the thermodynamic equilibrium and kinetic diffusion. The influences of the size and density of slag inclusions on the variation of their composition were also evaluated. The residence times of the inclusions in the molten steel were studied by simulating the flow of molten steel and the movement of the inclusions in the mold and steel cavity. The results show that after entrainment into the molten steel, the mold flux reacts continuously with the molten steel, which results in a significant change in its composition. The time required for the transformation was related to the diameter and density of inclusions. The larger the diameter and the bigger the density, the longer the time was required for the transformation. The time required for the transformation had a root relationship with the diameter of inclusions, and had a quadratic function with density of the inclusions. The average residence time of the inclusions in the molten steel decreased with increases in the diameter of the inclusions and the pulling speed. There would be enough time for the small inclusions to transform into the compositions of defects once they are entrained into the molten steel. The average residence time of the large inclusions is less than the time required for the transformation, while the maximum residence time is much longer than the time required for the transformation, which indicates that some inclusions with larger size still have enough residence time to transform from the initial composition to the composition of defects.
- slag inclusions /
- kinetic model /
- mold flux /
- line defect /
- tinplate

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圖 1 鍍錫板缺陷處不同位置的化學成分

Figure 1. Composition of inclusions at defects on the tinplate

下載: 全尺寸圖片幻燈片

圖 2 結晶器保護渣成分和缺陷處化學成分的對比

Figure 2. Comparison of compositions of mold flux and inclusions at defects

下載: 全尺寸圖片幻燈片

圖 3 卷渣類夾雜物–鋼液反應示意圖

Figure 3. Schematic of the reaction between the inclusions and the steel

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圖 4 計算得到的卷渣類夾雜物成分隨時間的演變

Figure 4. Calculated evolution of the composition of mold-flux-entrapped inclusions over time

下載: 全尺寸圖片幻燈片

圖 5 模型計算的夾雜物成分和與鍍錫板缺陷處成分的對比

Figure 5. Comparison of the calculated and experimental compositions of inclusions at defects

下載: 全尺寸圖片幻燈片

圖 6 不同尺寸卷渣類夾雜物成分的演變。（a）d_inc=10 μm；（b）d_inc=30 μm；（c）d_inc=300 μm；（d）d_inc=500 μm；（e）d_inc=1 mm；（f）d_inc=3 mm

Figure 6. Transformation of inclusions of different diameters entrained in the mold flux: (a) d_inc=10 μm; (b) d_inc=30 μm; (c) d_inc=300 μm; (d) d_inc=500 μm; (e) d_inc=1 mm; (f) d_inc=3 mm

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圖 7 夾雜物轉變為缺陷處化學成分所需時間與夾雜物尺寸的關系

Figure 7. Relationship between the size of inclusions and the time required for their transformation

下載: 全尺寸圖片幻燈片

圖 8 不同初始密度卷渣類夾雜物成分演變

Figure 8. Evolution of the composition of inclusions with different initial densities entrained with the mold flux

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圖 9 轉變為缺陷處夾雜物成分所需時間與夾雜物初始密度的關系

Figure 9. Relationship between the initial density of inclusions and the time required for their transformation

下載: 全尺寸圖片幻燈片

圖 10 不同拉速對夾雜物軌跡的影響。（a）1.4 m?min^?1；（b）1.8 m?min^?1

Figure 10. Influence of pulling speed on the trajectory of inclusions: (a) 1.4 m?min^?1；(b) 1.8 m?min^?1

下載: 全尺寸圖片幻燈片

圖 11 拉速為1.8 m?min^?1條件下鋼液中夾雜物尺寸和平均停留時間的關系

Figure 11. Relationship between the size of inclusions and the average residence time at a pulling speed of 1.8 m?min^?1

下載: 全尺寸圖片幻燈片

表 1 鍍錫板缺陷處不同位置元素含量（質量分數）

Table 1. Chemical composition at different defect locations on the tinplate %

Position	O	F	Na	Mg	Al	Si	Ca	Mn	Fe
P1	29.71	4.46	7.58	1.99	5.08	11.97	9.63	0.9	28.68
P2	29.81	4.93	6.36	2.79	3.94	12.78	13.59	1.64	24.15
P3	37.2	6.2	3.65	1.05	2.25	13.13	24.24	1.45	10.83
P4	19.21	7.15	3.13	3.16	0.69	11.72	18.61	1.1	35.23
P5	30.08	4.64	6.71	2.19	4.62	13.96	15.19	1.45	21.17
P6	32.38	7.27	6.33	3.09	5.54	14.61	12.09	1.29	17.06

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表 2 結晶器保護渣成分

Table 2. Composition of the mold flux %

Composition	CaO	SiO₂	Al₂O₃	Fe₂O₃	MgO	K₂O+Na₂O	CaF₂
Mass fraction	28.49	37.11	3.34	0.97	3.31	10.09	16.69

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表 3 鋼液化學成分

Table 3. Chemical composition of the molten steel %

Composition	C	Si	Mn	P	S	T.Al	[Al]	T.N	T.O
Mass fraction	0.03	0.01	0.22	0.007	0.006	0.047	0.044	0.0029	0.0016
Note：T.Al is total mass fraction of aluminium; T.N is total mass fraction of nitrogen; T.O is total mass fraction of oxygen.

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表 4 夾雜物與鋼液反應動力學模型所考慮的化學反應

Table 4. Chemical reactions considered in the current model

Reaction	Δ$ G^{\ominus} $ / (J·mol^?1)	Reference
$\left[ {{\rm{Ca}}} \right]{\rm{ + }}\left[ {\rm{O}} \right]{\rm{ = }}\left( {{\rm{CaO}}} \right)$	$\Delta {G^{\ominus} } = - 138240.86 - 63.0T$	[21]
${\rm{2}}\left[ {{\rm{Al}}} \right]{\rm{ + 3}}\left[ {\rm{O}} \right]{\rm{ = }}\left( {{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}} \right)$	$\Delta { G^{\ominus}} = - 1206220 + 390.39T$	[21]
$\left[ {{\rm{Si}}} \right]{\rm{ + 2}}\left[ {\rm{O}} \right]{\rm{ = }}\left( {{\rm{Si}}{{\rm{O}}_{\rm{2}}}} \right)$	$\Delta { G^{\ominus}} = - 581900 + 221.8T$	[21]
$\left[ {{\rm{Mg}}} \right]{\rm{ + }}\left[ {\rm{O}} \right]{\rm{ = }}\left( {{\rm{MgO}}} \right)$	$\Delta { G^{\ominus}} = - 89960 - 82.0T$	[21]
$\left[ {{\rm{Mn}}} \right]{\rm{ + }}\left[ {\rm{O}} \right]{\rm{ = }}\left( {{\rm{MnO}}} \right)$	$\Delta { G^{\ominus}} = 288150 - 128.3T$	[21]

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表 5 不同元素在鋼液中的擴散系數

Table 5. Diffusivities of elements in the molten steel 10^?9 m²?s^?1

Element	Ca	Al	Si	Mn	Mg	O
D_M	3.5	3.5	4.36	4.4	3.5	2.96

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表 6 模型初始條件

Table 6. Initial conditions used in the calculations

Initial mass fraction of steel / %	C	Si	Mn	P	S	[Al]	T.N	T.O	[Ca]	[Mg]
Initial mass fraction of steel / %	0.03	0.01	0.22	0.007	0.006	0.044	0.0029	0.0016	0.0001	0.0001

Initial mass fraction of inclusion / %	CaO	SiO₂		Al₂O₃	Fe₂O₃		MgO	Na₂O		CaF₂
Initial mass fraction of inclusion / %	28.49	37.11		3.34	0.97		3.31	10.09		16.69

Parameters	T_steel / ℃		ρ_steel / (kg?m^?3)		μ_steel / (Pa·s）		ρ_inc / (kg?m^?3)		d_inc / μm
Parameters	1500		7000		0.0067		2500		100

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