稀土Ce对X20Co马氏体耐热钢蠕变性能的影响  

Effect of Ce Addition on Creep Properties of X20Co Martensitic Heat-resistant Steel

作　　者：向钰琳 杨仁贤 蔡欣 胡小强[3,4] 李殿中 XIANG Yulin;YANG Renxian;CAI Xin;HU Xiaoqiang;LI Dianzhong(School of Rare Earths,University of Science and Technology of China,Ganzhou 341000,China;Ganjiang Innovation Academy,Chinese Academy of Sciences,Ganzhou 341000,China;Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China)

机构地区：[1]中国科学技术大学稀土学院,赣州341000 [2]中国科学院赣江创新研究院,赣州341000 [3]中国科学院金属研究所沈阳材料科学国家研究中心,沈阳110016 [4]中国科学技术大学材料科学与工程学院,沈阳110016

出　　处：《材料研究学报》2024年第10期721-731,共11页Chinese Journal of Materials Research

基　　金：福建省STS计划配套项目(2020T3009);中国科学院青年创新促进会优秀项目(Y2021060);中国科学院率先计划王宽诚“产研人才”项目(2021001);沈阳市中青年科技创新人才支持计划项目(RC220474)。

摘　　要：采用扫描电子显微镜(SEM)、场发射透射电子显微镜(STEM)及能谱仪(EDS)等实验手段,系统研究了稀土元素Ce对X20Co马氏体耐热钢(X20Co)微观组织和蠕变行为的影响。结果表明,在680~720℃、100~200 MPa实验条件下,Ce元素添加提高了X20Co蠕变寿命,且随着Ce含量的提高,X20Co的蠕变寿命显著延长。在700℃/150 MPa时,添加质量分数为0.005%和0.012%Ce的X20Co其蠕变断裂时间分别为77.6和119.0 h,比不添加Ce的蠕变断裂时间(58.3 h)分别提高33%和104%以上。不添加Ce和添加质量分数为0.005%、0.012%Ce的X20Co,对应的蠕变应力指数分别为5.05和4.76、4.49,蠕变激活能分别为572.3、595.0、642.1 kJ/mol,蠕变门槛应力分别为58.3、87.8、82.5 MPa。三种不同Ce元素含量X20Co的蠕变机制均为位错攀移控制机制,Ce元素的添加,并未改变X20Co的蠕变机制。但是,Ce元素的添加,其明显提高了X20Co的蠕变激活能和门槛应力。蠕变前和断裂后微观组织对比分析表明,X20Co中存在三类析出相:沿晶界分布的富W大尺寸M6C和富Cr的较大尺寸M_(23)C_(6),以及弥散分布在晶内的富V细小MC。Ce元素添加,能够减少大尺寸块状M6C的数量,有效改善X20Co的蠕变性能。The X20Co martensitic heat-resistant steel(X20Co)has notable characteristics such as elevated high-temperature strength,as well as commendable resistance to oxidation and corrosion.The X20Co has been extensively employed as high-temperature working components of die-casting machines for Mg-alloys.Nevertheless,the prolonged exposure of die-casting machine components to high-temperature magnesium alloy liquid might result in deformation and fracture failure due to the occurrence of high-temperature creep.Therefore,it is imperative to enhance the high-temperature creep resistance of X20Co and prolong the operational lifespan of hot-work components in die-casting machinery.Rare earth(RE)elements,including Ce,are seen as potential means to improve the creep properties of X20Co.However,the effect of Ce on the microstructure and creep performance of X20Co have not been reported yet.In this study,the impact of Ce on the creep properties and microstructural characteristics of X20Co by applied stress within 100~200 MPa at 680~720℃ is investigated by means of electronic creep testing machine,scanning electron microscope(SEM),transmission electron microscope(STEM),and energy-dispersive X-ray spectroscopy(EDS).The findings indicate that the incorporation of Ce can enhance the creep resistance of X20Co.Moreover,as a subsequence of the increase of Ce concentration,there is a remarkable and substantial improvement in the creep life of X20Co.As an illustration,by the testing condition of 700℃/150 MPa,the X20Co steel with 0.005%and 0.012%Ce(mass fraction)presents enhanced creep rupture time c.a.33%and 103%respectively superior to that of the plain X20Co.The creep stress exponent,activation energy,and threshold stress of the plain X20Co are determined to be 5.05,572.3 kJ/mol and 58.3 MPa,respectively.Correspondingly,those of the X20Co with 0.005%(mass fraction)Ce are 4.76,595.0 kJ/mol and 87.8 MPa,respectively.Whereas,those of the X20Co with 0.012%(mass fraction)Ce are 4.49,642.1 kJ/mol and 82.5 MPa,respectively.It is indicated

关 键 词：金属材料 X20Co马氏体耐热钢 稀土元素 析出相 蠕变性能 微观组织 

分 类 号：TG142.1[一般工业技术—材料科学与工程]