气氛保护电渣重熔过程中氧化物–CaS复合夹杂物的演变

刘伟建; 史成斌; 徐昊驰; 郑顶立; 吕士刚; 李晶; 郭宝善

doi:10.13374/j.issn2095-9389.2020.03.12.s08

气氛保护电渣重熔过程中氧化物–CaS复合夹杂物的演变

doi: 10.13374/j.issn2095-9389.2020.03.12.s08

1.
北京科技大学钢铁冶金新技术国家重点实验室，北京 100083
2.
邢台钢铁有限责任公司，邢台 054027

基金项目: 国家自然科学基金资助项目（51874026，52074027）

详细信息

通讯作者:
E-mail: chengbin.shi@ustb.edu.cn

中图分类号: TF769.2
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出版历程
- 收稿日期: 2020-03-12
- 刊出日期: 2020-12-25

Evolution of oxide–CaS complex inclusions during protective atmosphere electroslag remelting

1.
State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China
2.
Xingtai Iron and Steel Co., Ltd., Xingtai 054027, China

More Information

Corresponding author: E-mail: chengbin.shi@ustb.edu.cn

摘要

摘要: 利用扫描电镜分析了自耗电极和电渣重熔钢中夹杂物的特征，结合热力学计算，分析了氧硫复合夹杂物在电渣重熔过程中的转变机理。结果表明，电渣重熔采用气氛保护结合脱氧操作可以将自耗电极全氧质量分数由0.0017%降低至0.0008%。电渣重熔之后钢中小于3 μm夹杂物的比例显著增加。自耗电极中的夹杂物为CaS与含质量分数3%和11%左右MgO的CaO–Al₂O₃–SiO₂–MgO结合的两类复合夹杂物。电渣过程未被去除的氧化物夹杂中的SiO₂被钢液中酸溶铝还原，保留至电渣锭中。电渣锭中含约1%MgO和2%SiO₂且成分均匀的CaO–Al₂O₃–SiO₂–MgO是在电渣过程中新生的夹杂物。自耗电极中的CaS通过分解为钢液中溶解Ca和S，以及通过与液态氧化物夹杂中Al₂O₃反应的途径在电渣过程被去除。电渣锭中低熔点氧化物夹杂周围环状CaS是钢液凝固过程中溶解S、酸溶铝Al与氧化物夹杂中CaO的反应产物，高熔点氧化物夹杂周围环状CaS是钢液凝固过程中Ca和S偏析后反应新生的夹杂物。复合夹杂物中补丁状CaS是在电渣重熔钢液冷却过程中由复合夹杂物熔体中析出的。
- 非金属夹杂物 /
- 硫化物 /
- 电渣重熔 /
- 超低氧 /
- 硫化物容量
Abstract: The inclusions in the consumable steel electrode and electroslag remelted steel were characterized using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). The evolution mechanism of oxide–sulfide complex inclusions during electroslag remelting (ESR) was elucidated based on inclusion experimental identification and thermodynamic calculation. The results show that the combination of protective atmosphere and deoxidation operation during ESR lowers the total oxygen content from 0.0017% in the electrode to 0.0008% in the ingot. The number proportion of the inclusions smaller than 3 μm in the steel greatly increases after ESR. The inclusions in the steel electrode are two oxide–sulfide complex types of CaS+CaO–Al₂O₃–SiO₂–MgO containing about 3% MgO and CaS+CaO–Al₂O₃–SiO₂–MgO containing about 11% MgO. SiO₂ in the original oxide inclusions that had not been removed in ESRR process was reduced by soluble aluminum in liquid steel, and the products remain in the ESR process until in remelted ingot. The CaO–Al₂O₃–SiO₂–MgO inclusions with uniform elements distribution, which contain about 1%MgO and about 2%SiO₂, in the ingot are newly formed oxide inclusions in the ESR. CaS inclusions in the steel electrode were removed during the ESR through dissociating into soluble calcium and sulfur in liquid steel, and in the way of reacting with Al₂O₃ in liquid oxide inclusions. The shell-type CaS around low-melting-temperature oxide inclusion generated as a result of the reaction between CaO in the oxide inclusion and dissolved aluminum and sulfur in liquid steel during solidification of liquid steel in the ESR process. The shell-type CaS around high-melting-temperature oxide inclusion is the reaction products of enriched soluble Ca and S during solidification of liquid steel. Patch-type CaS in the oxide–sulfide complex inclusion precipitated from the complex inclusion melt during the cooling of liquid steel in the ESR process.
- non-metallic inclusion /
- sulfide /
- electroslag remelting /
- ultralow oxygen /
- sulfide capacity

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图 1 自耗电极和电渣锭中夹杂物的尺寸分布

Figure 1. Size distribution of inclusions in the consumable steel and remelted steel

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图 2 自耗电极中典型夹杂物的元素面分布（a,b,c）和EDS谱图（d,e）（图（d）和（e）中的EDS谱图分别对应图（a）和（c）中夹杂物的EDS点分析）

Figure 2. Element mappings (a,b,c) and EDS spectra (d,e) of complex inclusions in the consumable steel electrode (EDS spectra in (d) and (e) correspond to the inclusions shown in (a) and (c), respectively).

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图 3 自耗电极中氧化物夹杂在CaO–Al₂O₃–SiO₂三元相图中的成分分布。（a）3%MgO；（b）11%MgO

Figure 3. Composition distribution of oxide inclusions in steel electrode on the CaO–Al₂O₃–SiO₂ phase diagram: (a) 3%MgO; (b) 11%MgO

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图 4 电渣锭中典型夹杂物的元素面分布（a,b,c,d）和EDS谱图（e,f）（图（e）和（f）中的EDS谱图分别对应图（a）和（d）中夹杂物的EDS点分析）

Figure 4. Element mappings (a,b,c,d) and EDS spectra (e,f) of complex inclusions in the remelted ingot (EDS spectra in (e) and (f) correspond to the inclusions shown in (a) and (d), respectively)

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图 5 电渣锭中氧化物夹杂在CaO–Al₂O₃–SiO₂三元相图中的成分分布。（a）3%MgO；（b）11%MgO

Figure 5. Composition distribution of oxide inclusions in the remelted ingot on the CaO–Al₂O₃–SiO₂ phase diagram: (a) 3%MgO; (b) 11%MgO

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图 6 氧化物夹杂中SiO₂与酸溶铝[Al]_s反应的吉布斯自由能变化值随温度的变化

Figure 6. Gibbs free energy change for the reaction between SiO₂ in the oxide inclusion and dissolved aluminum in liquid steel against the temperature

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图 7 氧化物夹杂中MgO与酸溶铝[Al]_s反应的吉布斯自由能变化值随温度的变化

Figure 7. Gibbs free energy change for the reaction between MgO in the oxide inclusion and dissolved aluminum in liquid steel against the temperature

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图 8 CaO–Al₂O₃–SiO₂–MgO夹杂物的硫化物容量随温度的变化

Figure 8. Dependence of the sulfide capacity of CaO–Al₂O₃–SiO₂–MgO inclusion on temperature

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表 1 自耗电极的化学成分（质量分数）

Table 1. Chemical composition of the consumable electrode and remelted ingot %

C	Si	Mn	S	Ni	Cr	V	Mo	Ca	T.O	Al	Mg	N
0.39	1.15	0.42	0.0022	0.16	5.67	0.97	1.47	0.0008	0.0017	0.0150	0.0003	0.0083

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表 2 电渣锭的化学成分（质量分数）

Table 2. Chemical composition of the remelted ingot %

C	Si	Mn	S	Ni	Cr	V	Mo	Ca	T.O	Al	Mg	N
0.39	1.06	0.42	0.0016	0.16	5.67	0.97	1.47	0.0005	0.0008	0.0160	0.0002	0.0088

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表 3 采用的一阶活度相互作用系数数据^{[11, 21–22]}

Table 3. First-order interaction parameters $\mathop e\nolimits_i^j $ used in the present calculation

$\mathop e\nolimits_i^j $	C	Si	Mn	S	Ni	Cr	V	Ca	O	Al	N
Al	0.091	0.056	0.0035	0.035	–0.029	0.0096	—	–0.047	–1.98	0.045	–0.058
Si	0.18	0.11	0.002	0.056	0.005	–0.0003	0.025	–0.067	–0.23	0.058	0.09

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表 4 采用的一阶活度相互作用系数$e_i^j$^{[20, 22, 29]}

Table 4. First-order interaction parameters $e_i^j$ used in the present study^{[20, 22, 29]}

$\mathop e\nolimits_{\rm{i}}^j $	C	Si	Mn	S	Ni	Cr	V	Mo	Ca	O	Al
Ca	–0.34	–0.096	–0.0156	–140	–0.044	0.014	—	—	–0.002	–9000	–0.072
S	0.111	0.075	–0.026	–0.046	—	–0.0105	–0.019	0.0027	–110	–0.27	0.041
Mg	0.15	–0.096	—	—	–0.012	0.022	—	—	—	560	–0.27

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表 5 ξ的计算参数

Table 5. Parameters used for calculating ξ

Unary reaction	ξ_i
MgO	9573.07326
Al₂O₃	157705.276
SiO₂	168872.847
CaO	–3.3099425×10⁴

Binary reaction	ξ_mix
Al₂O₃–CaO	${y_{{\rm{A}}{{\rm{l}}^{{\rm{3 + }}}}}} \cdot {y_{{\rm{C}}{{\rm{a}}^{{\rm{2 + }}}}}} \cdot \left[ {98282.7968 + 55.07340941T} \right]$
Al₂O₃–SiO₂	${y_{{\rm{A}}{{\rm{l}}^{{\rm{3 + }}}}}} \cdot {y_{{\rm{S}}{{\rm{i}}^{{\rm{4 + }}}}}} \cdot \left[ {186850.468} \right]$
CaO–SiO₂	${y_{{\rm{C}}{{\rm{a}}^{{\rm{2 + }}}}}} \cdot {y_{{\rm{S}}{{\rm{i}}^{{\rm{4 + }}}}}} \cdot \left[ {97271.7695 + 72.874T} \right]$
MgO–SiO₂	${y_{{\rm{M}}{{\rm{g}}^{{\rm{2 + }}}}}} \cdot {y_{{\rm{S}}{{\rm{i}}^{{\rm{4 + }}}}}} \cdot \left[ {69740.322 - 224.084556T} \right]$

Ternary reaction	ξ_mix
Al₂O₃–MgO–CaO	${y_{{\rm{A}}{{\rm{l}}^{{\rm{3 + }}}}}} \cdot {y_{{\rm{M}}{{\rm{g}}^{{\rm{2 + }}}}}} \cdot {y_{{\rm{C}}{{\rm{a}}^{{\rm{2 + }}}}}} \cdot \left[ {4165955.5 - 1066.5663T - {\rm{3040801}}{\rm{.89}}{y_{{\rm{A}}{{\rm{l}}^{{\rm{3 + }}}}}}} \right]$
Al₂O₃– SiO₂–CaO	${y_{{\rm{A}}{{\rm{l}}^{{\rm{3 + }}}}}} \cdot {y_{{\rm{S}}{{\rm{i}}^{{\rm{4 + }}}}}} \cdot {y_{{\rm{C}}{{\rm{a}}^{{\rm{2 + }}}}}} \cdot \left[ { - 2035792.64 + {\rm{686}}{\rm{.044695}}T} \right]$
Al₂O₃–SiO₂–MgO	${y_{{\rm{A}}{{\rm{l}}^{{\rm{3 + }}}}}} \cdot {y_{{\rm{S}}{{\rm{i}}^{{\rm{4 + }}}}}} \cdot {y_{{\rm{M}}{{\rm{g}}^{{\rm{2 + }}}}}} \cdot \left[ {{\rm{156192}}{\rm{.588}} - {\rm{290}}{\rm{.498555}}T{\rm{ + 949447}}{\rm{.247}}{y_{{\rm{A}}{{\rm{l}}^{{\rm{3 + }}}}}}} \right]$
SiO₂–MgO–CaO	${y_{{\rm{M}}{{\rm{g}}^{{\rm{2 + }}}}}} \cdot {y_{{\rm{S}}{{\rm{i}}^{{\rm{4 + }}}}}} \cdot {y_{{\rm{C}}{{\rm{a}}^{{\rm{2 + }}}}}} \cdot \left[ { - {\rm{1526497}}{\rm{.71 + 625}}{\rm{.662842}}T{\rm{ + 1485255}}{\rm{.98}}{y_{{\rm{C}}{{\rm{a}}^{{\rm{2 + }}}}}}} \right]$

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