第36卷第8期 北京科技大学学报 Vol.36 No.8 2014年8月 Journal of University of Science and Technology Beijing Aug.2014 T一F钢凝固过程中TN的析出机理和规律 王金永”，刘建华)四，刘建飞”，冯美兰”，周明伟”，廖志”，贾友生) 1)北京科技大学治金工程研究院，北京1000832)涟源钢铁集团有限公司，涟源417009 ☒通信作者，E-mail:liujianhua@metall.usth.cd.cn 摘要结合治金热力学和凝固偏析模型分析了TiF钢凝固过程中TN的析出特点.THF钢凝固前期钢液中TN夹杂无 法生成，固相中TN源自低温固相析出：凝固固相分数达到0.64时，T、N组元在凝固前沿富集程度增加，凝固前沿固相中开 始有TN析出：凝固末期，T和N的富集程度进一步增大，固液相中均能有TN析出.采用扫描电镜分析了TN在铸坯中的分 布，从铸坯表层到中心TN数量和尺寸存在显著变化：从铸坯表层向中心方向TN尺寸不断增大，平均尺寸从1~2μm增大到 5m,在距离表层70-80mm处尺寸达到最大：在铸坯厚度中间位置，TiN尺寸较大，平均尺寸为5um左右：在铸坯中心TN尺 寸又有所变小，平均尺寸为3μm左右：在铸坯表层TN密集程度较高，在铸坯中间和中心TN数量密集程度显著降低.F钢 铸坯中TN析出时机及其尺寸和数量与T、N组元偏析和凝固冷却速度关系密切. 关键词F钢：氮化钛；凝固：偏析：析出 分类号TG142.1 Precipitation mechanism and behavior of TiN during Ti-IF steel solidification WANG Jin→ong',IU Jian--hua”,，LIU Jianfei”,FENG Mei-4an”,ZHO0 Ming-wei,LIAO Zhi,JIA You--sheng2》 1)Institute of Metallurgical Engineering,University of Science and Technology Beijing,Beijing 100083,China 2)Lianyuan Iron and Steel Corporation,Lianyuan 417009,China Corresponding author,E-mail:liujianhua@metall.ustb.edu.cn ABSTRACT Characterization of TiN precipitation during Ti-F steel solidification was analyzed by thermodynamics and the solidifica- tion segregation model.It is found that TiN inclusions cannot precipitate in liquid steel before solidification.In the earlier stage of so- lidification,TiN precipitates at low temperature in solidified steel.When the solid fraction reaches to0.64,TiN can precipitate in solid steel around the solidification front at higher temperatures,due to the increased enrichment of Ti and N.However,at the end stage of solidification,TiN can not only precipitate in solidified steel,but also in molten steel,for the segregation of Ti and N is getting seri- ous.TiN distribution in the Ti-F slab was observed by scanning electron microscopy (SEM).The results show that the number and size of TiN precipitates vary a lot from the slab surface to the center.The TiN size is increasing from the slab surface to the center, from 1-2 um to 5 um,and it is maximum in the area of 70 to 80mm from the slab surface.In the middle of the slab in thickness,the TiN size is large,with an average size of 5m;while in the center of the slab,the TiN size is getting smaller again,with an average size of 3 pm.The TiN denseness is high in the surface layer of the slab,but decreases significantly in the center and middle.The pre- cipitation moment,the size and number of TiN precipitates are closely related with the segregation of Ti and N and the solidification rate. KEY WORDS IF steel:titanium nitride:solidification;segregation:precipitation F钢是超低碳无间隙原子钢的简称，被称为 定为碳氮化物，从而得到无间隙原子的洁净铁素 第三代超深冲钢.它采用钛、铌等强碳氮化合物形 体钢0-习 成元素，将超低碳钢中的碳、氮等间隙原子完全固 TiF钢中TN主要在连铸过程中形成，尺寸处 收稿日期：2013-05-27 DOI:10.13374/j.issn1001-053x.2014.08.006:http:/journals.ustb.edu.cn第 36 卷 第 8 期 2014 年 8 月 北京科技大学学报 Journal of University of Science and Technology Beijing Vol． 36 No． 8 Aug． 2014 Ti--IF 钢凝固过程中 TiN 的析出机理和规律 王金永1) ，刘建华1) ，刘建飞1) ，冯美兰1) ，周明伟2) ，廖 志2) ，贾友生2) 1) 北京科技大学冶金工程研究院，北京 100083 2) 涟源钢铁集团有限公司，涟源 417009  通信作者，E-mail: liujianhua@ metall． ustb． edu． cn 摘 要 结合冶金热力学和凝固偏析模型分析了 Ti--IF 钢凝固过程中 TiN 的析出特点． Ti--IF 钢凝固前期钢液中 TiN 夹杂无 法生成，固相中 TiN 源自低温固相析出; 凝固固相分数达到 0. 64 时，Ti、N 组元在凝固前沿富集程度增加，凝固前沿固相中开 始有 TiN 析出; 凝固末期，Ti 和 N 的富集程度进一步增大，固液相中均能有 TiN 析出． 采用扫描电镜分析了 TiN 在铸坯中的分 布，从铸坯表层到中心 TiN 数量和尺寸存在显著变化: 从铸坯表层向中心方向 TiN 尺寸不断增大，平均尺寸从 1 ～ 2 μm 增大到 5 μm，在距离表层 70 ～ 80 mm 处尺寸达到最大; 在铸坯厚度中间位置，TiN 尺寸较大，平均尺寸为 5μm 左右; 在铸坯中心 TiN 尺 寸又有所变小，平均尺寸为 3 μm 左右; 在铸坯表层 TiN 密集程度较高，在铸坯中间和中心 TiN 数量密集程度显著降低． IF 钢 铸坯中 TiN 析出时机及其尺寸和数量与 Ti、N 组元偏析和凝固冷却速度关系密切． 关键词 IF 钢; 氮化钛; 凝固; 偏析; 析出 分类号 TG 142. 1 Precipitation mechanism and behavior of TiN during Ti-IF steel solidification WANG Jin-yong1) ，LIU Jian-hua1)  ，LIU Jian-fei1) ，FENG Mei-lan1) ，ZHOU Ming-wei2) ，LIAO Zhi2) ，JIA You-sheng2) 1) Institute of Metallurgical Engineering，University of Science and Technology Beijing，Beijing 100083，China 2) Lianyuan Iron and Steel Corporation，Lianyuan 417009，China  Corresponding author，E-mail: liujianhua@ metall． ustb． edu． cn ABSTＲACT Characterization of TiN precipitation during Ti-IF steel solidification was analyzed by thermodynamics and the solidifica￾tion segregation model． It is found that TiN inclusions cannot precipitate in liquid steel before solidification． In the earlier stage of so￾lidification，TiN precipitates at low temperature in solidified steel． When the solid fraction reaches to 0. 64，TiN can precipitate in solid steel around the solidification front at higher temperatures，due to the increased enrichment of Ti and N． However，at the end stage of solidification，TiN can not only precipitate in solidified steel，but also in molten steel，for the segregation of Ti and N is getting seri￾ous． TiN distribution in the Ti-IF slab was observed by scanning electron microscopy ( SEM) ． The results show that the number and size of TiN precipitates vary a lot from the slab surface to the center． The TiN size is increasing from the slab surface to the center， from 1--2 μm to 5 μm，and it is maximum in the area of 70 to 80 mm from the slab surface． In the middle of the slab in thickness，the TiN size is large，with an average size of 5 μm; while in the center of the slab，the TiN size is getting smaller again，with an average size of 3 μm． The TiN denseness is high in the surface layer of the slab，but decreases significantly in the center and middle． The pre￾cipitation moment，the size and number of TiN precipitates are closely related with the segregation of Ti and N and the solidification rate． KEY WOＲDS IF steel; titanium nitride; solidification; segregation; precipitation 收稿日期: 2013--05--27 DOI: 10． 13374 /j． issn1001--053x． 2014． 08． 006; http: / /journals． ustb． edu． cn IF 钢是超低碳无间隙原子钢的简称，被称为 第三代超深冲钢． 它采用钛、铌等强碳氮化合物形 成元素，将超低碳钢中的碳、氮等间隙原子完全固 定为碳氮化物，从而得到无间隙原子的洁净铁素 体钢［1 － 2］． Ti--IF 钢中 TiN 主要在连铸过程中形成，尺寸处