硅对9Cr-1.5WVTa低活化马氏体钢力学性能的影响

基于中国正在研究的聚变堆用9Cr-1.5WVTa低活化马氏体钢(CLAM钢),研究了添加合金元素硅对CLAM钢力学性能的影响。结果表明,添加0.2%Si使得CLAM钢的抗拉强度和屈服强度明显提高,钢的塑性和冲击韧性同时也得到一定提高,其中,韧脆转变温度(DBTT)由-13℃降至-30℃。未添加和添加0.29%Si的CLAM钢均为全马氏体组织,无δ铁素体存在。硅的添加使得9Cr-1.5WVTaSi钢的晶粒细化,从而提高了钢的拉伸和冲击性能。     

用马尿酸-丁醇作萃取剂从钇族希土中分离钇

(1)用0.04M的马尿酸-丁醇溶液作萃取剂萃取希土,在pH?6时,钇位于轻镧元素部分的钕与钐之间,其萃取率低于其他钇族希土元素.可借此性质自钇族希土中分离钇. (2)经过三级萃取,可自含70.5%Y_2O_3的钇族希土原料中,获得纯度为90.8—93.6%的Y_2O_3,收率约35%.当用二次循环萃取方式时,收率大约提高至55%. (3)研究了氨水添加量、萃取级数、溶液中希土浓度、水相与有机相的体积比等因素对萃取分离钇的影响。     

硅对CLAM钢微观结构和力学性能的影响

文章研究了合金元素硅对CLAM钢的力学性能和微观结构的影响。实验表明,在CLAM钢中添加0.2％的Si会使其屈服强度和抗拉强度明显提高,同时使CLAM钢的韧脆转变温度升高,韧性降低。在光学显微镜下观察,CLAM钢呈现回火马氏体组织,Si的添加使奥氏体晶粒细化,致使CLAM钢的强度升高、韧性降低。在透射电子显微镜下观察,回火板条马氏体是其主要结构,存在针状和颗粒状两种形态的碳化物;利用透射电子显微镜选区衍射方法可知,呈颗粒状的碳化物是M23C6型碳化物。Si的添加使马氏体板条的宽度变小。     

慢正电子束研究质子辐照CLAM钢产生的缺陷及其退火行为

为了研究中国低活化马氏体CLAM钢的辐照损伤机理,本文利用慢正电子技术研究了质子辐照CLAM钢时所产生的缺陷及其退火回复行为,发现辐照在材料中产生空位团数密度随质子注量增加而增多,而其尺度增大并不明显.辐照仅产生原子尺度的空位和空位团,400℃退火可以使缺陷很好地消除.此外分析了硅对CLAM钢辐照性能的影响,实验上没有观察到硅的添加抑制了质子辐照缺陷的产生.     

用于HL-2A装置的新型硬X射线探测器

介绍了一种应用于托卡马克等离子诊断领域的新型硬X射线探测器,该探测器主要由硅酸钇镥(Lutetium-yttrium Oxyorthosilicate,LYSO)闪烁体和硅光电倍增管(Silicon Photomultiplier,Si PM)组成。基于项目应用需求,对探测器的选型和基于粒子输运蒙特卡罗仿真软件GEANT4的探测器设计加以阐述,并搭建了前端的探测系统,在HL-2A托卡马克装置上进行了现场诊断实验。实现了硬X射线空间能谱和辐射强度分布的诊断测量。实验表明该探测器阵列具有10 ms的时间分辨率,同时具有结构紧凑、使用方便等特点,能够满足等离子体诊断中硬X射线动态能谱和强度分布测量的诊断需求。     

真空电磁离心铸造1025碳素钢的组织及拉伸性能

采用真空电磁离心铸造方法研究了1025碳素结构钢铸管在950、1 250、1 450 r/min 3种离心转速和0、0.052、0.085和0.115 T 4种磁感应强度作用下的组织和室温拉伸性能.结果表明在磁场作用下,铸态组织得到明显细化,室温强度与拉伸塑性得以提高,达到了对热轧态材料要求的标准.     

钇对9Cr-2WVTa低活化马氏体钢力学性能的影响

研究了稀土合金元素钇对聚变堆用低活化马氏体钢9Cr-2WVTa力学性能的影响,分析了钇在低活化马氏体钢中的冶金行为.研究结果表明,钇元素容易在钢中聚集形成富钇的块状夹杂,割裂了基体的连续性,容易破裂形成微孔;轧板中这些富钇块夹杂沿着轧制方向成条线状分布,使得在拉伸和冲击断裂时出现断口分层现象,降低了钢的力学性能.     

甲基乙烯基硅泡沫材料在复合条件下的辐射效应研究

为考察甲基乙烯基硅泡沫材料在不同条件下的辐射效应,开展了受压状态下材料经⁶⁰Co γ射线辐照后的热老化和湿热老化实验。采用扫描电镜、傅里叶转换红外光谱仪、固体核磁共振仪、万能材料试验机和蠕变松弛试验机等手段剖析了材料微观结构和宏观性能。结果表明,不同条件下老化后甲基乙烯基硅泡沫材料的泡孔有减小的趋势。²⁹Si交叉极化的NMR分析发现材料中有机硅链段峰的强度随吸收剂量的增大而升高,¹³C交叉极化的NMR分析表明γ射线辐照后材料的结构规整性有所降低。辐射后热老化样品的拉伸强度总比辐射后湿热老化样品的低,辐射老化和湿热老化的协同作用对材料的应力松弛率影响非常明显。     

国产304NG控氮不锈钢应用性能研究

通过向奥氏体不锈钢中加入适量的氮和降低碳含量,可以提高钢的强度,改善钢的耐腐蚀性能,而基本上不影响钢的塑性和韧性.本文对核工程用304NG控氮不锈钢的应用性能进行了研究,包括材料的基本特性和应力腐蚀、均匀腐蚀等性能.结果表明,国产304NG控氮不锈钢的综合性能满足核工程需求,与国外同类产品处于同一水平.     

以水杨酸-丁醇作萃取剂从钇族希土元素中分离钇

我们测定了水杨酸-丁醇萃取钍和十一个希土元素的萃取率,观察到在pH=5.5—7时钇的萃取率位于轻镧采元素的钕与钐之间,在同一pH值下,钇的萃取率较重镧系元素低,因此有可能从钇族希土元素中分离钇.这样,我们在半逆流连续萃取装置中进行了从钇族希土元素中分离钇的研究.系统地做了氨水加入量、水杨酸浓度、希土溶液浓度等条件试验.在适当的条件下经一次萃取,Y_2O_3纯度可从70%提高到95—98%,收率为57%左右.钇的交叉部分经二次循环,可得纯度大于95%的Y_2O_3,总收率为68%.因而证实了上面的推断是正确的,同时提出了一个成本便宜、操作简便,能连续、快速分离出纯度为95—98%的Y_2O_3的新方法.     

硅对低活化马氏体钢电子辐照行为的影响

利用超高压透射电子显微镜研究了两种成分的低活化马氏体钢(CLAM钢)的辐照损伤行为。结果表明：电子辐照能在未添加硅的CLAM钢中产生辐照空洞;在450℃下辐照至14dpa时,空洞数密度约为8.7×10²¹m^－3,辐照肿胀率约为0.26％;在450℃下的辐照肿胀率明显比500℃下的高;当损伤率为2×10^－3dpa/s时,添加合金元素硅能显著提高CLAM钢的抗辐照肿胀能力,未在添加硅的CLAM钢中实验观察到辐照空洞的形成。在450℃下进行辐照时,添加硅的CLAM钢出现明显的辐照共格析出现象。     

Influence of non-metal inclusions on mechanical properties of CLAM steel

The effect of the size and distribution of non-metal inclusions on mechanical properties of the China low activation martensitic steel (CLAM) was investigated. The tensile and Charpy V-notch impact tests showed that electroslag remelting improved the tensile properties and reduced the ductile brittle transition temperature (DBTT). Inclusion detection of CLAM by optical microscopy and scanning electron microscope showed that both the dimensions and quantities of the alumina inclusions decreased and their distributions became more uniform after remelting. The better refinement and distribution uniformity of alumina inclusions were considered as the main possible reasons for the improvement of the mechanical properties of CLAM steel after remelting.     

Effect of direct and reheated quenching on microstructure and mechanical properties of CLAM steels

Direct and reheated quenching on microstructural mechanical properties of China Low Activation Martensitic (CLAM) steel was investigated. Three direct quenching and tempering (DQ&T) CLAM steels were rolled at the same finish rolling temperature with different quenching rate, and their microstructures and mechanical properties were compared with those of a reheated quenching and tempering (RQ&T) CLAM steel. DQ&T process was proven to strengthen the tensile property but lower the toughness compared to RQ&T process due to the finer austenite grain size formed under RQ&T process. Tensile property first increased with quenching rate and then decreased. The reason for this was discussed.     

中国抗中子辐照钢的抗辐照设计与验证

聚变堆等未来先进核能系统要求材料在强流高能中子辐照下长期保持良好的结构稳定性和机械性能。为适应未来先进核能技术发展的需要,中国科学院核能安全技术研究所•凤麟团队牵头研发了具有我国自主知识产权的中国抗中子辐照钢--CLAM钢。CLAM钢的设计考虑了未来核能清洁性的要求,以及苛刻服役环境中材料抗辐照、耐高温、耐腐蚀等性能要求。通过中子学计算分析设计了低活化成分范围,基于选择性纳米相析出进行了抗辐照、耐高温性能优化设计。针对材料的抗辐照性能,利用国内外中子、离子、电子及等离子体辐照设施开展了系列辐照考验研究,通过多角度表征辐照前后材料的微观结构和宏观性能,综合评估了材料的辐照性能,并与国际上同类材料在相近或相同条件下的辐照性能进行了对比分析,结果表明CLAM钢具有良好的抗辐照性能。     

Microstructure and its influence on mechanical properties of CLAM steel

The microstructure of China Low Activation Martensitic steel (CLAM) and its influence on mechanical properties were investigated. The tensile test showed that the strength of CLAM (HEAT 0603A) was higher than that of HEAT 0408B at room temperature, and the reverse results were obtained at elevated temperatures. The results indicated that the microstructure was composed of dispersived carbide particles and lath martensite with high dislocation density. The main precipitation phases were Cr-rich M₂₃C₆ carbides precipitated mainly along the lath boundaries and prior-austenite grain boundaries and Ta-rich MX particles precipitated mainly in the laths and lath boundaries. The finer lath was the main reason for the higher strength of HEAT 0603A compared with HEAT 0408B at room temperature; contrasted with the lower strength at high temperature. Heavier hot forging deformation degree was considered as the main possible reason for the decrease of martensite lath width in HEAT 0603A.     

Present status of development of high chromium steel for Japanese FBR components

This paper presents the establishment of the provisional specifications and material strength standard of the high chromium (Cr) steels for fast breeder reactor (FBR) components. For the improvement of toughness and ductility of the steels, a series of mechanical tests and metallurgical examinations are performed for several kinds of high Cr steels with the controlled balance of tungsten (W) and molybdenum (Mo). In addition, the effect of heat treatment condition on material properties is also investigated. Based on these results, it is revealed that W should be diminished to achieve better ductility and toughness and that it is difficult to improve the long-term properties by changing heat treatment condition. Then the provisional specifications of the high Cr steel for FBR components are given and the provisional material strength standard is proposed for the specifications of the steel. The standard obtained in this study is utilized for the FBR plant design.     

430℃下2.98dpa中子辐照后CLAM钢的拉伸和冲击性能

利用高通量工程试验堆HFETR开展了CLAM钢430℃下2.98dpa的中子辐照实验,通过辐照前后拉伸和冲击性能测试与对比分析,研究了CLAM钢的中子辐照硬化和脆化效应。结果显示,CLAM钢辐照后室温测试的抗拉强度和屈服强度分别为710 MPa和615 MPa,较辐照前分别下降16 MPa和-0.5MPa,总延伸率减小1%,断面收缩率下降4%,保持良好的强度、塑性和韧性。冲击测试表明,CLAM钢辐照前后韧脆转变温度基本相同,上平台能量无明显变化,约为217J,未出现明显辐照脆化。CLAM钢的抗辐照性能略优于其他低活化铁素体/马氏体RAFM钢在类似辐照条件下的性能。     

Ring test of 304 stainless steel tube oxidized in high temperature steam

The residual mechanical strength and ductility of 304 stainless steel claddings were studied in tests of ring compression, ring tension and hardness. The tests were made after the specimens had been heated in steam and in argon gas to temperatures between 900° C and 1350° C. The effects of crystal grain growth and oxygen absorption in the metal on the residual properties were also studied. The experiments showed that the claddings retained their ductility well at temperatures below 1300° C and when the oxide scale thickness was below 40% of the initial wall thickness. The claddings maintained a constant level of residual strength when heated at temperatures over 1000° C or when the oxide thickness was over five percent. These results were used to support our proposals for limits on stainless steel cladding damage in a LOCA.