D0:10.13374.issn1001-053x.2013.07.008 第35卷第7期 北京科技大学学报 Vol.35 No.7 2013年7月 Journal of University of Science and Technology Beijing Jul.2013 汽车大梁钢中第二相粒子析出行为 黄耀)，赵征志)区，赵爱民)，孙薇)，赵代银)，包阔) 1)北京科技大学冶金工程研究院，北京1000832)河北钢铁集团承德钢铁集团有限公司，承德067102 ☒通信作者，E-mail:zhaozhzhi@ustb.cdu.cn 摘要运用热动力学理论和Oswald熟化理论研究了不同氮含量汽车大梁钢中第二相粒子的析出和熟化行为.研究发 现钢中N含量的增加会促进V(C,N)在奥氏体中析出从而细化铁素体晶粒，当氮的质量分数增至4.2×10-4时铁素体晶 粒尺寸能细化至4.7.形核率-温度曲线和析出-温度-时间曲线表明氮含量的增加可以扩大奥氏体区中最大形核率的 温度范围，氮的质量分数由5.5×10-5增至4.2×10-4时其最快析出的鼻点温度由840℃上升至968℃.透射电镜观察 显示氮含量的增加明显降低析出V(C,N)粒子的尺寸.VN在奥氏体中的Oswald熟化速率计算表明熟化速率随温度的 降低不断减少，同时增加N含量还可以有效降低析出粒子的熟化速率，从而抑制沉淀析出的第二相粒子的熟化长大过 程 关键词汽车钢：氮：析出：Ostwald熟化：碳氮化物：晶粒细化 分类号TG142.41 Precipitation behavior of secondary phases in automobile beam steel HUANG Yao),ZHAO Zheng-zhi),ZHAO Ai-min),SUN Wei),ZHAO Dai-yin )BAO Kuo2) 1)Research Institute of Metallurgy Engineering,University of Science and Technology Beijing,Beijing 100083,China 2)Chenggang Company,Hebei Iron and Steel Group,Chengde 067102,China Corresponding author,E-mail:zhaozhzhi@ustb.edu.cn ABSTRACT The precipitation and ripening behavior of secondary phases in automobile beam steel with different nitrogen contents were investigated by the thermo-kinetic theory and the Ostwald ripening theory.It is found that increasing the content of nitrogen in the steel can promote the precipitation of V(C.N)in austenite,thus the ferrite grains are greatly refined,and the ferrite grain size is decreased to 4.7 um when the content of nitrogen increases to 4.2x10-4.The curve of nucleation rate to temperature calculated by the thermodynamic theory shows that nitrogen can effectively expand the temperature zone of the biggest nucleation rate,and the precipitation-temperature-time curve demonstrates that the shortest incubation temperature can rise from 840 C to 968 C when the content of nitrogen increases from 5.5x10-5 to 4.2x10-4.Transmission electron microscopy observations reveal that the size of precipitated V(C,N)is effectively decreased with the increasing content of nitrogen.The calculated Ostwald ripening rate of VN in austenite indicates that the ripening rate weakens with the temperature dropping,and moreover increasing the content of nitrogen also can decrease the ripening rate to inhibit the ripening growth of the precipitated secondary phases. KEY WORDS automobile steel:nitrogen;precipitation:Ostwald ripening:carbonitrides;grain refinement 目前，钒微合金钢被广泛应用在汽车大梁用低合金钢的总体性能四.对微合金碳氮化物的析 钢以及建筑用螺纹钢筋上.在钢中加入微量的合 出行为来说，热动力学分析是一种非常有效的方 金元素V与N后，可以阻碍晶粒再结晶和高温 法2-3)].研究含钒汽车大梁钢中第二相粒子的析出 奥氏体的长大，并且由于V(C,N)在奥氏体和铁 行为，对实际生产中制定合理的热轧控冷工艺有重 素体中的析出产生沉淀强化，从而显著改善高强 要的指导意义.本文研究了一般氮含量（质量分数 收稿日期：2012-04-29第 35 卷 第 7 期 北 京 科 技 大 学 学 报 Vol. 35 No. 7 2013 年 7 月 Journal of University of Science and Technology Beijing Jul. 2013 汽车大梁钢中第二相粒子析出行为 黄 耀1)，赵征志1) ，赵爱民1)，孙 薇1)，赵代银1)，包 阔2) 1) 北京科技大学冶金工程研究院，北京 100083 2) 河北钢铁集团承德钢铁集团有限公司，承德 067102 通信作者，E-mail: zhaozhzhi@ustb.edu.cn 摘 要 运用热动力学理论和 Oswald 熟化理论研究了不同氮含量汽车大梁钢中第二相粒子的析出和熟化行为. 研究发 现钢中 N 含量的增加会促进 V(C,N) 在奥氏体中析出从而细化铁素体晶粒，当氮的质量分数增至 4.2×10−4 时铁素体晶 粒尺寸能细化至 4.7 µm. 形核率–温度曲线和析出–温度–时间曲线表明氮含量的增加可以扩大奥氏体区中最大形核率的 温度范围，氮的质量分数由 5.5×10−5 增至 4.2×10−4 时其最快析出的鼻点温度由 840 ℃上升至 968 ℃. 透射电镜观察 显示氮含量的增加明显降低析出 V(C,N) 粒子的尺寸. VN 在奥氏体中的 Oswald 熟化速率计算表明熟化速率随温度的 降低不断减少，同时增加 N 含量还可以有效降低析出粒子的熟化速率，从而抑制沉淀析出的第二相粒子的熟化长大过 程. 关键词 汽车钢；氮；析出；Ostwald 熟化；碳氮化物；晶粒细化 分类号 TG142.41 Precipitation behavior of secondary phases in automobile beam steel HUANG Yao 1), ZHAO Zheng-zhi 1) , ZHAO Ai-min 1), SUN Wei 1), ZHAO Dai-yin 1), BAO Kuo 2) 1) Research Institute of Metallurgy Engineering, University of Science and Technology Beijing, Beijing 100083, China 2) Chenggang Company, Hebei Iron and Steel Group, Chengde 067102, China Corresponding author, E-mail: zhaozhzhi@ustb.edu.cn ABSTRACT The precipitation and ripening behavior of secondary phases in automobile beam steel with different nitrogen contents were investigated by the thermo-kinetic theory and the Ostwald ripening theory. It is found that increasing the content of nitrogen in the steel can promote the precipitation of V(C,N) in austenite, thus the ferrite grains are greatly refined, and the ferrite grain size is decreased to 4.7 µm when the content of nitrogen increases to 4.2×10−4 . The curve of nucleation rate to temperature calculated by the thermodynamic theory shows that nitrogen can effectively expand the temperature zone of the biggest nucleation rate, and the precipitation-temperature-time curve demonstrates that the shortest incubation temperature can rise from 840 ℃ to 968 ℃ when the content of nitrogen increases from 5.5×10−5 to 4.2×10−4 . Transmission electron microscopy observations reveal that the size of precipitated V(C,N) is effectively decreased with the increasing content of nitrogen. The calculated Ostwald ripening rate of VN in austenite indicates that the ripening rate weakens with the temperature dropping, and moreover increasing the content of nitrogen also can decrease the ripening rate to inhibit the ripening growth of the precipitated secondary phases. KEY WORDS automobile steel; nitrogen; precipitation; Ostwald ripening; carbonitrides; grain refinement 目前，钒微合金钢被广泛应用在汽车大梁用 钢以及建筑用螺纹钢筋上. 在钢中加入微量的合 金元素 V 与 N 后，可以阻碍晶粒再结晶和高温 奥氏体的长大， 并且由于 V(C,N) 在奥氏体和铁 素体中的析出产生沉淀强化，从而显著改善高强 低合金钢的总体性能 [1] . 对微合金碳氮化物的析 出行为来说，热动力学分析是一种非常有效的方 法[2−3] . 研究含钒汽车大梁钢中第二相粒子的析出 行为，对实际生产中制定合理的热轧控冷工艺有重 要的指导意义. 本文研究了一般氮含量 (质量分数 收稿日期：2012-04-29 DOI:10.13374/j.issn1001-053x.2013.07.008