工程科学学报，第38卷，第5期：691698,2016年5月 Chinese Journal of Engineering,Vol.38,No.5:691-698,May 2016 D0l:10.13374/j.issn2095-9389.2016.05.014:http://journals.ustb.edu.cn 纳米贝氏体的热力学分析及强韧化研究 智超》，赵爱民123)四，何建国2》，赵复庆12”，车英建2) 1)北京科技大学治金工程研究院，北京1000832)北京科技大学现代交通金属材料与加工技术北京实验室，北京100083 3)北京科技大学钢铁共性技术协同创新中心，北京100083 ☒通信作者，E-mail:aimin..zhao@usth.edu.cn 摘要针对目前高碳高硅低温贝氏体（纳米结构贝氏体）相变速度缓慢的现状，采用贝氏体相变热力学理论分析主要合金 元素对低温贝氏体相变驱动力的影响，设计了新型纳米结构贝氏体钢成分0.83C-2.44Si0.43Mn0.73A1.利用膨胀仪研究 该成分贝氏体钢在不同温度下的相变整体动力学，综合使用扫描电子显微镜、X射线衍射、电子背散射衍射等方法研究热处 理工艺对实验钢组织和力学性能的影响.结果表明，350℃等温转变贝氏体的抗拉强度为1401MPa,延伸率为42.21%，强塑 积可达59136MP·%,在室温拉伸过程中发生明显的相变诱导塑性效应：230℃等温转变组织中贝氏体铁素体片层厚度小于 100nm,抗拉强度达2169MPa. 关键词贝氏体钢：纳米结构材料：力学性能研究：热力学分析 分类号TG142.2 Thermodynamic analysis and strength-toughness research of nanobainite ZHI Chao,ZHAO Ai-min,HE Jian-guo,ZHAO Fu-qing2,CHE Ying jian) 1)Engineering Research Institute,University of Science and Technology Beijing,Beijing 100083,China 2)Beijing Laboratory forModern Transportation Advanced Metal Materials and Processing Technology,University of Science and Technology Beijing, Beijing 100083,China 3)Collaborative Innovation Center of Steel Technology,University of Science and Technology Beijing,Beijing 100083,China Corresponding author,E-mail:aimin.zhao@ustb.edu.cn ABSTRACT In view of slow phase transformation rate in high-earbon,silicon-rich and low-alloy bainite steel (nanostructured bain- ite steel),the effects of alloy elements on the overall kinetics of low temperature bainite phase transformation were analyzed by using the thermodynamic theory of bainite phase transformation,and a composition of 0.83C-2.44Si-0.43 Mn-0.73Al (mass fraction,% was designed to develop a novel nanostructured bainitic steel.The overall phase transformation kinetics of this new designed nanobai- nitic steel at different temperatures were investigated by dilatometry.The effects of heat treatment parameters on the microstructure and mechanical properties were analyzed by scanning electron microscopy,X-ray diffraction and electron backscatter diffraction.It is found that the nanobainitic steel,which exhibited excellent mechanical properties with an ultimate tensile strength of 1401 MPa,a total elon- gation rate of 42.21%and a strength and ductility product of 59136 MPa%,can be obtained by austempering at 350C.In addition, transformation-induced plasticity (TRIP)effect appears during tensile testing at room temperature.When austempered at 230 C,the nanobainitic steel has a finer microstructure with the thickness of bainite ferrite laths less than 100 nm,and its tensile strength can reach up to 2169 MPa. KEY WORDS bainitic steel:nanostructured materials:mechanical properties investigation:thermodynamic analysis 收稿日期：2015-05-08 基金项目：国家自然科学基金资助项目(51271035)工程科学学报，第 38 卷，第 5 期: 691--698，2016 年 5 月 Chinese Journal of Engineering，Vol． 38，No． 5: 691--698，May 2016 DOI: 10． 13374 /j． issn2095--9389． 2016． 05． 014; http: / /journals． ustb． edu． cn 纳米贝氏体的热力学分析及强韧化研究 智 超1，2) ，赵爱民1，2，3) ，何建国1，2) ，赵复庆1，2) ，车英建1，2) 1) 北京科技大学冶金工程研究院，北京 100083 2) 北京科技大学现代交通金属材料与加工技术北京实验室，北京 100083 3) 北京科技大学钢铁共性技术协同创新中心，北京 100083  通信作者，E-mail: aimin． zhao@ ustb． edu． cn 摘 要 针对目前高碳高硅低温贝氏体( 纳米结构贝氏体) 相变速度缓慢的现状，采用贝氏体相变热力学理论分析主要合金 元素对低温贝氏体相变驱动力的影响，设计了新型纳米结构贝氏体钢成分 0. 83C--2. 44Si--0. 43Mn--0. 73Al． 利用膨胀仪研究 该成分贝氏体钢在不同温度下的相变整体动力学，综合使用扫描电子显微镜、X 射线衍射、电子背散射衍射等方法研究热处 理工艺对实验钢组织和力学性能的影响． 结果表明，350 ℃等温转变贝氏体的抗拉强度为 1401 MPa，延伸率为 42. 21% ，强塑 积可达 59136 MPa·% ，在室温拉伸过程中发生明显的相变诱导塑性效应; 230 ℃ 等温转变组织中贝氏体铁素体片层厚度小于 100 nm，抗拉强度达 2169 MPa． 关键词 贝氏体钢; 纳米结构材料; 力学性能研究; 热力学分析 分类号 TG142. 2 收稿日期: 2015--05--08 基金项目: 国家自然科学基金资助项目( 51271035) Thermodynamic analysis and strength-toughness research of nanobainite ZHI Chao 1，2) ，ZHAO Ai-min1，2，3)  ，HE Jian-guo 1，2) ，ZHAO Fu-qing1，2) ，CHE Ying-jian1，2) 1) Engineering Ｒesearch Institute，University of Science and Technology Beijing，Beijing 100083，China 2) Beijing Laboratory forModern Transportation Advanced Metal Materials and Processing Technology，University of Science and Technology Beijing， Beijing 100083，China 3) Collaborative Innovation Center of Steel Technology，University of Science and Technology Beijing，Beijing 100083，China  Corresponding author，E-mail: aimin． zhao@ ustb． edu． cn ABSTＲACT In view of slow phase transformation rate in high-carbon，silicon-rich and low-alloy bainite steel ( nanostructured bain￾ite steel) ，the effects of alloy elements on the overall kinetics of low temperature bainite phase transformation were analyzed by using the thermodynamic theory of bainite phase transformation，and a composition of 0. 83C--2. 44Si--0. 43Mn--0. 73Al ( mass fraction，% ) was designed to develop a novel nanostructured bainitic steel． The overall phase transformation kinetics of this new designed nanobai￾nitic steel at different temperatures were investigated by dilatometry． The effects of heat treatment parameters on the microstructure and mechanical properties were analyzed by scanning electron microscopy，X-ray diffraction and electron backscatter diffraction． It is found that the nanobainitic steel，which exhibited excellent mechanical properties with an ultimate tensile strength of 1401 MPa，a total elon￾gation rate of 42. 21% and a strength and ductility product of 59136 MPa·% ，can be obtained by austempering at 350 ℃ ． In addition， transformation-induced plasticity ( TＲIP) effect appears during tensile testing at room temperature． When austempered at 230 ℃，the nanobainitic steel has a finer microstructure with the thickness of bainite ferrite laths less than 100 nm，and its tensile strength can reach up to 2169 MPa． KEY WOＲDS bainitic steel; nanostructured materials; mechanical properties investigation; thermodynamic analysis