第36卷第1期 北京科技大学学报 Vol.36 No.1 2014年1月 Journal of University of Science and Technology Beijing Jan.2014 常化后冷却工艺对1600MPa级超高强钢组织性能的 影响 余伟，齐越四，李亮，孙广杰，万德成，董长征 北京科技大学高效轧制国家工程研究中心，北京100083 ☒通信作者，E-mail:qyuc08@163.com 摘要为改善高强度钢的塑性和韧性，对中碳低合金马氏体高强度钢分别采用常化后空冷+回火和常化后控冷+回火工 艺，研究常化后冷却工艺对钢中残余奥氏体及力学性能的影响.采用扫描电镜获得钢的组织形态，利用X射线衍射和电子背 散射衍射技术分析钢中残余奥氏体的体积分数、形貌和分布.发现两种工艺下均得到板条马氏体+残余奥氏体组织，残余奥 氏体均匀分布在板条之间，随工艺参数不同，其体积分数在3%~10%变化.常化后加速冷却能显著细化马氏体板条，提高钢 的屈服强度和抗拉强度100MP以上，冲击功下降4J.残余奥氏体的体积分数随常化控冷终冷温度的升高呈现先升高后降低 的变化，常化后的控制冷却也可以作为进一步改善马氏体类型钢组织和性能的方法， 关键词超高强钢；常化处理；控制冷却：马氏体：残余奥氏体；力学性能 分类号TG142.1 Effect of cooling process after normalizing on the microstructure and properties of 1600 MPa ultra-high strength steel YU Wei,QI Yue,LI Liang,SUN Guang-jie,WANG De-eheng,DONG Chang-zheng National Engineering Research Center for Advanced Rolling Technology,University of Science and Technology Beijing,Beijing 100083,China Corresponding author,E-mail:qiyue08@163.com ABSTRACT The effects of two different processes,normalizing with air cooling tempering and normalizing with controlled cooling tempering,on the retained austenite and mechanical properties of medium-earbon low-alloy martensitic ultra-high strength steel were investigated to improve its plasticity and toughness.The microstructure of the steel was observed by scanning electron microscopy (SEM).The volume fraction,shape and distribution of retained austenite in the steel were measured by X-ay diffraction (XRD)and electron back-scattering diffraction (EBSD).The results show that lath martensite and retained austenite (M+RA)are obtained by the two processes and a uniform distribution of retained austenite is located between lath martensites.The volume fraction of retained austenite varies from 3%to 10%with treatment parameters.Normalizing with controlled cooling can significantly refine lath martensite while the yield strength and tensile strength increase more than 100 MPa and the impact energy decreases by 4J.When the quenching temperature rises,the volume fraction of retained martensite increases firstly and then decreases.Normalizing with controlled cooling can also act as a method for improving the microstructure and properties of martensitic steel. KEY WORDS high strength steel:normalizing:controlled cooling:martensitic steel;retained austenite:mechanical properties 为节约能源和原材料，发展超高强钢已成为近 布及稳定性受热处理工艺影响较大.感应加热回火 年来钢铁材料研究的重点方向之一)，但随着强 能使调质高强度钢获得更多的残余奥氏体，有利于 度的不断提升，延韧性不足成为制约超高强钢应用 改善钢的塑性和韧性园：回火工艺参数的改变可以 的重要技术瓶颈。研究表明，残余奥氏体可以改善 改变贝氏体及马氏体板条间残余奥氏体膜的稳定 钢的延韧性；而残余奥氏体属于亚稳组织，其分 性，提高钢的屈服强度，改善冲击韧性.常规的 收稿日期：2012一1105 DOI:10.13374/j.issn1001-053x.2014.01.009:http:/journals.ustb.edu.cn第 36 卷 第 1 期 2014 年 1 月 北京科技大学学报 Journal of University of Science and Technology Beijing Vol． 36 No． 1 Jan． 2014 常化后冷却工艺对 1600 MPa 级超高强钢组织性能的 影响 余 伟，齐 越，李 亮，孙广杰，万德成，董长征 北京科技大学高效轧制国家工程研究中心，北京 100083  通信作者，E-mail: qiyue08@ 163． com 摘 要 为改善高强度钢的塑性和韧性，对中碳低合金马氏体高强度钢分别采用常化后空冷 + 回火和常化后控冷 + 回火工 艺，研究常化后冷却工艺对钢中残余奥氏体及力学性能的影响． 采用扫描电镜获得钢的组织形态，利用 X 射线衍射和电子背 散射衍射技术分析钢中残余奥氏体的体积分数、形貌和分布． 发现两种工艺下均得到板条马氏体 + 残余奥氏体组织，残余奥 氏体均匀分布在板条之间，随工艺参数不同，其体积分数在 3% ～ 10% 变化． 常化后加速冷却能显著细化马氏体板条，提高钢 的屈服强度和抗拉强度 100 MPa 以上，冲击功下降 4 J． 残余奥氏体的体积分数随常化控冷终冷温度的升高呈现先升高后降低 的变化，常化后的控制冷却也可以作为进一步改善马氏体类型钢组织和性能的方法． 关键词 超高强钢; 常化处理; 控制冷却; 马氏体; 残余奥氏体; 力学性能 分类号 TG142． 1 Effect of cooling process after normalizing on the microstructure and properties of 1600 MPa ultra-high strength steel YU Wei，QI Yue  ，LI Liang，SUN Guang-jie，WANG De-cheng，DONG Chang-zheng National Engineering Ｒesearch Center for Advanced Ｒolling Technology，University of Science and Technology Beijing，Beijing 100083，China  Corresponding author，E-mail: qiyue08@ 163． com ABSTＲACT The effects of two different processes，normalizing with air cooling + tempering and normalizing with controlled cooling + tempering，on the retained austenite and mechanical properties of medium-carbon low-alloy martensitic ultra-high strength steel were investigated to improve its plasticity and toughness． The microstructure of the steel was observed by scanning electron microscopy ( SEM) ． The volume fraction，shape and distribution of retained austenite in the steel were measured by X-ray diffraction ( XＲD) and electron back-scattering diffraction ( EBSD) ． The results show that lath martensite and retained austenite ( M + ＲA) are obtained by the two processes and a uniform distribution of retained austenite is located between lath martensites． The volume fraction of retained austenite varies from 3% to 10% with treatment parameters． Normalizing with controlled cooling can significantly refine lath martensite while the yield strength and tensile strength increase more than 100 MPa and the impact energy decreases by 4 J． When the quenching temperature rises，the volume fraction of retained martensite increases firstly and then decreases． Normalizing with controlled cooling can also act as a method for improving the microstructure and properties of martensitic steel． KEY WOＲDS high strength steel; normalizing; controlled cooling; martensitic steel; retained austenite; mechanical properties 收稿日期: 2012--11--05 DOI: 10． 13374 /j． issn1001--053x． 2014． 01． 009; http: / /journals． ustb． edu． cn 为节约能源和原材料，发展超高强钢已成为近 年来钢铁材料研究的重点方向之一［1--3］，但随着强 度的不断提升，延韧性不足成为制约超高强钢应用 的重要技术瓶颈． 研究表明，残余奥氏体可以改善 钢的延韧性［4--5］; 而残余奥氏体属于亚稳组织，其分 布及稳定性受热处理工艺影响较大． 感应加热回火 能使调质高强度钢获得更多的残余奥氏体，有利于 改善钢的塑性和韧性［6］; 回火工艺参数的改变可以 改变贝氏体及马氏体板条间残余奥氏体膜的稳定 性，提高钢的屈服强度，改善冲击韧性［7--9］． 常规的