终轧温度对高性能桥梁钢力学性能及组织的影响  

Effects of finish rolling temperature on mechanical property and microstructure in a high performance bridge steel

作　　者：余宏伟 董中波 吴开明 饶水林 胡锋 陈英 YU Hongwei;DONG Zhongbo;WU Kaiming;RAO Shuilin;HU Feng;CHEN Ying(The State Key Laboratory of Refractories and Metallurgy,Collaborative Innovation Center for Advanced Steels,International Research Institute for Steel Technology,Wuhan University of Science and Technology,Wuhan 430080,Hubei,China;Technology Center,Echeng Iron and Steel Co.,Ltd.,of Baowu Group,Ezhou 436002,Hubei,China;R&D Center of Baosteel,Wuhan 430080,Hubei,China)

机构地区：[1]武汉科技大学耐火材料与冶金省部共建国家重点实验室,高性能钢铁材料及其应用省部共建协同创新中心,国际钢铁研究院,湖北武汉430080 [2]宝武集团鄂城钢铁有限公司技术中心,湖北鄂州436002 [3]宝钢股份中央研究院,湖北武汉430080

出　　处：《钢铁研究学报》2023年第7期861-872,共12页Journal of Iron and Steel Research

基　　金：国家自然科学基金资助项目(U20A20279);广西科技计划资助项目(桂科AA22068080)。

摘　　要：利用拉伸、冲击试验机测试力学性能,采用光学显微镜、扫描电镜和透射电镜研究了终轧温度对高性能桥梁钢Q370qE力学性能和微观组织、晶界取向角度差、织构、位错和析出相形态的影响。结果表明:在875~803℃范围内降低终轧温度,钢的屈服强度和抗拉强度均提升,屈强比上升,韧脆转变温度降低,低温韧性提高。终轧温度为803℃时,钢的屈服强度、抗拉强度分别为420、542 MPa,-40℃的夏比冲击功均值为243 J。降低终轧温度有利于铁素体晶粒的细化和均匀性的提升,细化珠光体团束的尺寸,减少珠光体组织的数量,改变了珠光体形态,出现退化形态;但较低的终轧温度,珠光体组织由分散变为连续的条带,加重了钢的带状组织。同时降低终轧温度,促进了大角度晶界的形成和小角度晶界的减少,有利于晶粒<001>取向的减弱和<110>取向的增多;有利于晶内Nb/Ti碳氮化物析出相颗粒的细化及球状的形成,铁素体晶粒内部位错增多并大量缠结,也促进了Nb/Ti碳氮化物在位错上的形成。The mechanical properties of high performance bridge steel Q370qE were tested by tensile and impact testing machines.The effects of finishing rolling temperature on mechanical properties,microstructure,grain boundary orientation angle difference,texture,dislocation and precipitate morphology were studied by optical microscope,scanning electron microscope and transmission electron microscope.The results show that the yield strength,tensile strength and yield strength ratio of the steel increase when the finishing rolling temperature is reduced in the range of 875-803℃.The ductile brittle transition temperature is reduced and the low temperature toughness of the steel is improved.When the final rolling temperature is 803℃,the yield and tensile strength of the steel are 420MPa and 542MPa,respectively.The average Charpy impact energy is 243J at-40℃.Reducing the finishing rolling temperature is beneficial to refine the ferrite grain size and improve the uniformity.The size of pearlite cluster bundle and the number of pearlite structure reduce,some pearlite clusters are degenerated.The pearlite structure changes from dispersed to continuous strip,which increases the banded structure of the steel.The formation of large angle grain boundaries and the reduction of small angle grain boundaries in Q370qE steel,which is conducive to the weakening of grain<001>orientation and the increase of grain<110>orientation.The precipitations of Nb/Ti carbonitride in the grain are refined and spherical.The increase in internal dislocations and a large amount of entanglement in ferrite grains also promote the formation of Nb/Ti carbonitrides on dislocations.

关 键 词：终轧温度 低温韧性 退化珠光体 大角度晶界 析出相 

分 类 号：TG142.4[一般工业技术—材料科学与工程]