超低碳鋼精煉過程中Fe-Al-Ti-O類復合氧化物夾雜的演變與控制

顧超; 趙立華; 甘鵬

doi:10.13374/j.issn2095-9389.2019.06.007

超低碳鋼精煉過程中Fe-Al-Ti-O類復合氧化物夾雜的演變與控制

doi: 10.13374/j.issn2095-9389.2019.06.007

顧超¹,
趙立華^2, ,,
甘鵬¹

1.
北京科技大學鋼鐵冶金新技術國家重點實驗室, 北京 100083
2.
北京科技大學冶金與生態工程學院, 北京 100083

基金項目:

國家自然科學基金資助項目 5157419

詳細信息

通訊作者:
趙立華, E-mail: 15210951549@sina.cn

中圖分類號: TF769.2
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出版歷程
- 收稿日期: 2018-12-20
- 刊出日期: 2019-06-01

Revolution and control of Fe-Al-Ti-O complex oxide inclusions in ultralow-carbon steel during refining process

GU Chao¹,
ZHAO Li-hua^{2
, ,},
GAN Peng¹

1.
State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China
2.
School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China

More Information

Corresponding author: ZHAO Li-hua, E-mail: 15210951549@sina.cn

摘要

摘要: 超低碳鋼是一種重要的汽車用鋼材料, 鋼中通常添加鈦元素, 使其形成析出物, 提高鋼材的深沖性.然而鈦元素作為一種脫氧能力較強的元素, 進入鋼液中通常首先形成氧化物.為了減少含鈦氧化物夾雜的生成, 基于"轉爐-RH-連鑄"的超低碳鋼生產流程, 對RH精煉過程進行系統取樣, 分析了鋁脫氧劑加入后及合金化元素鈦加入后的氧、氮氣體含量變化及夾雜物特征變化, 并使用FactSage熱力學計算軟件對Fe-Al-Ti-O夾雜物穩定相圖進行計算.研究結果顯示, 含鈦類氧化物夾雜通常以Al₂O₃類夾雜物作為形核質點, 對其形成包裹狀夾雜物.若避免含Ti夾雜物的生成, 當鋼中Ti質量分數為0.1%時, 鋼中溶解Al質量分數應在0.01%以上.對含鈦氧化物的生成及長大流程進行研究, 通過對Al₂O₃夾雜物及Ti₂O₃夾雜物粗化率的計算及附著功的比較可知, Ti₂O₃夾雜物在1600℃時的熟化生長速率較Al₂O₃較大且Ti₂O₃夾雜物與Al₂O₃夾雜物相比不容易相互碰撞融合并從鋼液中去除.若提高精煉過程中的氧化物夾雜物去除率, 應嚴格控制含鈦氧化物類夾雜物的生成.
- 超低碳鋼 /
- RH精煉 /
- Al₂O₃夾雜物 /
- Ti₂O₃夾雜物
Abstract: Ultralow-carbon steel is an important material for automobile production. Titanium is usually added in this steel grade to form a precipitant and improve the deep drawing property of the steel. However, due to the deoxidation capacity of Ti, Ti addition will directly generate Ti-bearing oxide inclusions instead of the precipitant. To reduce the amount of Ti-bearing oxide inclusions, samples were collected during the RH refining based on the basic oxygen furnace-Ruhrstahl-Heraeus reactor-continuous casting (BOF-RH-CC) ultralow-carbon steel production process, and the oxygen content and inclusion characterization after Al addition and Ti addition were analyzed. The thermodynamics calculation software FactSage was adopted to calculate the Fe-Al-Ti-O inclusion stability phase diagram. The results show that the Al₂O₃ inclusion usually acts as the nucleation point of the Ti-bearing oxide inclusion, which wraps the Al₂O₃ inclusion to form the Al-Ti-O complex inclusion. To avoid the generation of the Ti-bearing oxide inclusions, the mass fraction of dissolved Al in the molten steel should be greater than 0.01% when the Ti mass fraction is 0.1%. Furthermore, the generation and growth behavior of the Ti-bearing oxide inclusion were also studied. Based on the calculation of the growth rate and the comparison of the adhesion work of the Al₂O₃ inclusion and the Ti₂O₃ inclusion, it is concluded that the growth rate of Ti₂O₃ inclusion is greater than that of Al₂O₃ inclusion, and it is more difficult for Ti₂O₃ inclusions to collide with each other and to be removed at 1600℃. Therefore, the generation of Ti-bearing oxide inclusions should be strictly controlled to improve the removal rate of oxide inclusions in ultralow-carbon steels.
- ultralow-carbon steel /
- RH refining /
- Al₂O₃ inclusion /
- Ti₂O₃ inclusion

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圖 1 加料及取樣示意圖

Figure 1. Schematic of charging and taking specimens

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圖 2 RH精煉過程中氣體含量變化: (a) 全氧; (b) 氮質量分數

Figure 2. Variation of the gas content during RH refining: (a) total oxygen content; (b) nitrogen content

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圖 3 RH精煉過程中氧化物夾雜物數量及尺寸特征變化

Figure 3. Variation of the amount and size characterization of oxide in-clusions during RH refining

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圖 4 RH精煉過程中氧化物類夾雜物的典型形貌. (a) RH進站; (b) 加Al后; (c) 加Ti后

Figure 4. Typical morphologies of oxide inclusions during RH refining: (a) beginning of RH; (b) after Al addition; (c) after Ti addition

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圖 5 Fe-Al-Ti-O夾雜物平衡相圖(1600℃)

Figure 5. Inclusion stability diagram of the Fe-Al-Ti-O system at 1600℃

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圖 6 超低碳鋼中典型氧化物類夾雜物形貌的演變機理

Figure 6. Revolution mechanism of typical oxide inclusions in ultralow-carbon steels

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圖 7 Al₂O₃及Ti₂O₃夾雜物粗化率變化

Figure 7. Variation of k_dof Al₂O₃and Ti₂O₃inclusions with oxygen content

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圖 8 Al₂O₃及Ti₂O₃夾雜物的附著功(W_ad) 比較

Figure 8. Comparison of the adhesion work (W_ad) of Al₂O₃and Ti₂O₃inclusions

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表 1 目標超低碳鋼主要成分(質量分數)

Table 1. Main composition of the target steel ? %

C	Si	Mn	S	P	Al	Ti	Nb
0. 002	0. 010	0. 100	0. 007	0. 015	0. 020	0. 020	0. 004

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表 2 Al₂O₃及Ti₂O₃夾雜物的相關表面性質參數及V₀

Table 2. Relative surface parameters and V₀of Al₂O₃and Ti₂O₃inclu-sions

夾雜物種類	γ_SV/(J·m^-2)	θ /(°)	V₀ /(m³·mol^-1)
Al₂O₃	0. 94^[14]	144^[15]	8. 6 × 10^-6
Ti₂O₃	1. 61^[16]	122^[16]	1. 13 × 10^-5

下載: 導出CSV

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