新型纳米复合强化9Cr-ODS钢的设计、组织与力学性能  

Microstructure and Mechanical Properties of a Novel Designed 9Cr-ODS Steel Synergically Strengthened by Nano Precipitates

作　　者：芮祥 李艳芬 张家榕[2,3] 王旗涛 严伟 单以银 RUI Xiang;LI Yanfen;ZHANG Jiarong;WANG Qitao;YAN Wei;SHAN Yiyin(School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China;Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;CAS Key Laboratory of Nuclear Materials and Safety Assessment,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]中国科学技术大学、材料科学与工程学院,沈阳110016 [2]中国科学院金属研究所、师昌绪先进材料创新中心,沈阳110016 [3]中国科学院金属研究所、中国科学院核用材料与安全评价重点实验室,沈阳110016

出　　处：《金属学报》2023年第12期1590-1602,共13页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目No.51971217;中国科学院金属研究所海外引进“优秀学者”人才项目No.JY7A7A111A1

摘　　要：设计了一种新型纳米氮化物(MX相)与氧化物协同强化的9Cr-ODS钢,并对粉末冶金制备材料在不同热处理后的力学性能与显微组织进行了测试表征。采用粉体热锻造固化成型替代热等静压工艺,制备的新型ODS钢获得了98%的良好致密度。材料正火及回火后的组织为回火马氏体,不存在明显的择优取向及粗、细混晶组织,平均晶粒尺寸约1μm。在晶界未观察到明显的M23C6型碳化物,但在基体内获得了大量尺寸在30~200 nm范围的MX析出相。同时,纳米氧化物析出相弥散分布,平均粒径约3.0 nm、数密度约1.9×10^(23) m^(-3)。力学性能测试表明:材料的显微硬度随正火温度从980℃升高至1200℃而逐渐降低,而随回火温度从700℃升高至800℃呈现先增加后降低的趋势;材料经1100℃、1 h正火及750℃、1 h回火后获得了最佳的强塑性,室温屈服强度、抗拉强度以及延伸率分别为1039 MPa、1103 MPa及20.5%,700℃下分别为291 MPa、333 MPa及16%。Oxide dispersion-strengthened(ODS)steels with nano-scale Y2O3 or Y-Ti-O oxides have been considered as potential structural materials used in advanced nuclear systems.In this work,a novel 9Cr-ODS steel,namely,MX-ODS steel,was designed by decreasing carbon content to eliminate conven-tional M23C6-type carbides and by increasing the content of nitrogen and vanadium to form MX-type precipitates.In addition,the MX-ODS steel was synergistically strengthened by nano-scale MX precipitates and oxides.After fabrication by powder metallurgy,microstructural observation,and mechanical property tests were conducted after different heat treatments.The density of the prepared materials using hot forging instead of hot isostatic pressing was about 98%.Results of the microstructure observation of the MXODS steel indicated that after normalizing and tempering,the tempered martensitic structure dominated,and the mean effective grain size was approximately 1μm.Moreover,the preferential orientation of coarse-grained and fine-grained mixed grains was not detected.By diminishing carbon content,M23C6-type carbides precipitated at the grain and sub-grain boundaries were eliminated.By contrast,MX-type precipitates with a diameter of approximately 30-200 nm were formed in the matrix.Furthermore,nanoscale Y-rich oxides with an average size of approximately 3.0 nm were dispersed in the matrix,and a number density can reach to approximately 1.9×10^(23 )m^(-3).Furthermore,“core-shell”structure precipitates were found,which were spherical in shape with a diameter ranging from 10 to 20 nm.Such precipitates also contained Y,Ta,and O as the core and V as the shell.The mechanical properties indicate that microhardness decreased from 372 to 320 HV with the increase of normalizing temperature from 980oC to 1200oC.In addition,microhardness decreased significantly after tempering but initially increased and then decreased with the increase of tempering temperature from 700oC to 800oC,with a peak microhardness at approximately 750oC.Excellent stre

关 键 词：ODS钢 MX析出相 纳米氧化物 显微组织 力学性能 

分 类 号：TL341[核科学技术—核技术及应用]