终轧温度对低屈强比桥梁耐候钢组织及力学性能的影响  

Effect of finish rolling temperature on microstructure and mechanical properties of bridge weathering steel with low yield ratio

作　　者：刘文胜 张可 徐党委[2] 孟少博 黄重[2] 夏志升[2] 张明亚 孙新军[3] Wensheng LIU;Ke ZHANG;Dangwei XU;Shaobo MENG;Zhong HUANG;Zhisheng XIA;Mingya ZHANG;Xinjun SUN(School of Metallurgical Engineering,Anhui University of Technology,Ma'anshan,Anhui 243032,China;Anyang Iron&Steel Group Co.,Ltd.,Anyang,Henan 455004,China;Department of Structural Steel,Central Iron and Steel Institute Co.,Ltd.,Beijing 100081,China)

机构地区：[1]安徽工业大学冶金工程学院,安徽马鞍山243032 [2]安阳钢铁集团有限责任公司,河南安阳455004 [3]钢铁研究总院有限公司,北京100081

出　　处：《过程工程学报》2024年第4期462-469,共8页The Chinese Journal of Process Engineering

基　　金：河南省博士后科研启动项目(编号:202103098);安徽省高等学校科学研究项目(编号:2023AH051090);国家自然科学基金资助项目(编号:51704008)。

摘　　要：采用Gleeble-3800热模拟试验机、拉伸试验机、显微硬度计等设备,并结合光学显微镜(OM)和电子背散射衍射(EBSD)等表征方法,研究了终轧温度对Cu-Cr-Ni低屈强比桥梁耐候钢组织和力学性能的影响,并阐明了其具体的变化机理。结果表明,终轧温度880℃下的Cu-Cr-Ni桥梁耐候钢组织为粒状贝氏体,随着终轧温度由880℃降低至800℃,组织中出现针状铁素体并逐渐增多;M/A岛的平均尺寸由1.3μm增大至3.3μm,且面积分数由21.7%增大至32.3%;基体中的位错密度显著升高,主要是由基体回复程度大幅降低导致的。此外,Cu-Cr-Ni桥梁耐候钢的硬度及屈服强度随着终轧温度的降低而有所升高,屈服强度由435 MPa增大至496 MPa,抗拉强度基本不变,约为710 MPa,这是由显微组织中的针状铁素体、M/A组元和位错密度等因素共同决定。屈强比增大但总体低于0.7,塑性略有提高。The effect of the finish rolling temperature on the microstructure and mechanical attributes of Cu-Cr-Ni bridge weathering steel,characterized by a low yield ratio,was exhaustively explored in this study.Advanced testing methodologies including the Gleeble-3800 thermal simulation tester,tensile tester,and Vickers hardness tester were employed,in conjunction with characterization techniques such as optical microscope(OM)and electron backscattered diffraction(EBSD).This comprehensive approach aimed to elucidate the specific mechanisms governing these transformative changes.The results of the investigation unveiled pivotal transformations within the microstructure of Cu-Cr-Ni bridge weathering steel.Initially rolled at 880℃,the steel exhibited a granular bainitic microstructure.A reduction in the finish rolling temperature to 800℃ushered in the formation of acicular ferrite,which gradually increased in prevalence.Simultaneously,the average size of the M/A islands expanded from 1.3 to 3.3μm,accompanied by an increase in the area fraction from 21.7%to 32.3%.Notably,a marked elevation in dislocation density within the matrix was observed,primarily attributed to the considerable reduction in the degree of matrix restitution.Furthermore,these microstructural modifications were mirrored by notable enhancements in the material's mechanical properties.The hardness and yield strength of the Cu-Cr-Ni bridge weathering steel experienced a pronounced upswing with diminishing finish rolling temperatures.The yield strength,in particular,exhibited a remarkable increase from 435 to 496 MPa.Contrarily,tensile strength remained relatively stable at approximately 710 MPa.These mechanical variations were intricately linked to the prevalence of acicular ferrite within the microstructure,the presence of M/A constituents,and the heightened dislocation density.Importantly,the yield ratio exhibited an increasing trend,albeit generally maintaining a level below 0.7,indicative of a subtle improvement in plasticity.This research not only

关 键 词：桥梁耐候钢 终轧温度 显微组织 力学性能 

分 类 号：TG142.1[一般工业技术—材料科学与工程] TG335[金属学及工艺—金属材料]