基于团簇结构模型的低活化铁素体/马氏体钢成分设计

使用"团簇加连接原子"结构模型研究了低活化铁素体/马氏体钢的成分特征,确定了BCCFe-Cr二元基础团簇式[CrFe14](Cr0.5Fe0.5),其中团簇[Cr-Fe14]是以溶质原子Cr为心周围被14个基体Fe包围的菱形十二面体。根据团簇式自洽放大和相似组元替代原则,添加V、Mn、Mo、W、Nb和C等合金元素得到2个系列团簇成分式,无C系列[Cr16Fe224](Cr8(V,Nb,Mn,Mo,W,Fe)8)和含C系列{[Cr16Fe224](Cr8(V,Nb,Mn,Mo,W,Fe)8)}C1。使用铜模吸铸快冷技术制备直径6 mm的合金棒,将其在1323 K保温0.5 h+水冷,随后在1023 K保温1 h+水冷。结果表明,无C系列置换固溶体合金为单一铁素体组织,含C系列合金的微观组织随着合金化组元种类和含量的不同而变化;合金的硬度随着组织的改变而改变,且置换固溶体系列合金的硬度随着合金体电子浓度VEC/Ra3的增加而单调降低。     

合金元素对 Nb2Mo2Si合金相平衡及Nb2 Nb 5Si 3共晶组织形态的影响

采用电弧熔炼法制备了 Nb220Si210Mo、Nb220Si210Mo23M (M = Cr , Al , Ti) (原子分数) 四种 Nb2Mo2Si基超高温合金。利用 SEM、EDS、XRD等实验技术对铸造合金的相组成与组织形态进行了观察和分析。Nb220Si210Mo 合金由铌固溶体 (Nb SS) 与βNb 5Si 3化合物两相构成 , 其铸造组织包含大量片层状共晶 (Nb SS 2βNb 5Si 3) 组织。少量合金元素 Cr (3 at %) 能够改变 Nb220Si210Mo 合金的相平衡关系 , Nb220Si210Mo23Cr 的铸造组织中不仅存在 Nb SS和βNb 5Si 3 , 而且还出现少量 Cr 2Nb相 ; 而添加合金元素 Al、Ti (3 at %) 并不改变 Nb220Si210Mo 合金的相平衡关系。添加 Cr 使 Nb SS 2 βNb 5Si 3共晶组织失去了平直片层特征 ; Al 有利于共晶组织中片层状共晶形成 ; 添加 Ti使共晶组织呈现羽毛状特征。合金化使 Nb与βNb 5Si 3的晶格常数发生变化 : Nb的晶格常数均变小; Nb220Si210Mo23Cr合金中βNb 5Si 3的 c/ a值减小 , 其它 3种合金中βNb 5Si 3的 c/ a值增大。     

三维原子探针表征淬回火Cr-Mo-V-Ni中合金钢的元素分布

将Cr-Mo-V-Ni中合金钢在1 030℃奥氏体化保温0.5h后油淬,在600℃回火2次,每次2h。结合光学显微镜(OM)和扫描电子显微镜(SEM),采用三维原子探针(3DAP)技术分析了淬火态和回火态各元素原子的三维空间分布以及碳化物内部和碳化物/基体界面处元素分布和成分变化。结果表明,淬火试样中C原子由于自回火和短程扩散出现了较为明显的片状偏聚,而其他合金原子Cr、Mn、Mo、Si、V和Ni基本分布均匀;回火试样中C、Cr、Mo和V发生共偏聚形成厚度约10nm的合金碳化物M23C6,Si原子形成一层薄薄的偏聚层包裹着M23C6,而Ni又包裹着Si原子而偏聚于最外层。     

耐蚀热强合金ЭП670的性能及其应用

属于奥氏体一类的低碳焊接合金670(OOX20H32T)原先在苏联国内并无生产,这种合金具有良好的热强性、好的工艺性能、好的耐蚀性及组织稳定性等特点。根据苏5632—72标准规定合金的化学成份为(%):C≤0.05、Mn≤0.7、Si≤0.7、Cr=19-22、Ni=32-34、Ti=0.25-0.60、Al≤0.5。     

地面汽轮机叶片的腐蚀防护

前苏联大型电站用汽轮机叶片的腐蚀防护工作,分两个方向进行,即保证协调合金化和改进涂层系统。 根据前苏联中央锅炉汽轮机研究设计院的数据,要获得抗腐蚀性良好的高温合金,首先应对合金化元素的浓度作出下列限制(％重量):Cr≤(18～20);Ti≤3;Al≤(2～3);Mo≤4;Zr(0.05～1.0);对合金化元素的比例作出下列限制:Cr~(1/2)Ti/Al≥(3～6);Ti/Al≥(0.7～1.0);Cr/Al≥5。     

含Al耐热奥氏体不锈钢的团簇式成分设计

表面生成Al2O3保护膜的奥氏体不锈钢具有良好的高温服役性能,为了使Al强烈促进铁素体的生成需要精确匹配奥氏体稳定元素Ni和Al的含量。为此,本文先引入“团簇加连接原子”结构模型,解析该类不锈钢的成分特征,确定其16原子团簇式,进而结合当量计算并基于橡树岭实验室推出的成分,固定C含量(质量分数)为0.1%,设计了固定Ni含量提高Al(代替Cr)含量和固定Al含量提高Ni(代替Fe)含量两个成分系列,分别为Al _x Si_0.05Nb_0.15-Fe_8.7Ni_3.0Mn_0.3-Cr_3.6-x Mo_0.2(x=0.8,1.0和1.1)和Al₁Si_0.05Nb_0.15-Fe_11.7-y Ni _y Mn_0.3-Cr_2.6Mo_0.2(y=3.2,3.4,3.7和4.0),研究了Ni和Al的不同匹配对固溶水淬(1250℃/1.5 h)加时效态(800℃/24 h)奥氏体稳定性的影响。Ni含量为3.0的16原子团簇式,Al含量为0.8时为单相奥氏体;Al含量为1.0和1.1时,奥氏体失稳而铁素体形成。在Al含量为1.0的16原子团簇式中,Ni含量为3.2~4.0时均为单相奥氏体。即在16原子团簇式模型下Al_0.8(2.45%)和Al₁(3.08%)分别需要Ni_3.0(20.00%)和Ni_3.2(21.43%)以避免形成铁素体,最终确定该类不锈钢的理想团簇式为[(Al,Si,Nb)₁-(Fe,Ni,Mn)₁₂](Cr,Mo,W)₃。     

多元合金团簇构型优化的研究

为了研究多元合金基体的稳定性,探讨了获得多元合金团簇平衡几何构型的途径,根据随机行走思想编写了多元合金构型优化的计算程序,并铸造了3种合金样品,其基体成分分别为Fe7Cr0.68Mn2.0V1.47Ni1.37Si0.7C,Fe8Cr0.74Mn2.3V1.45Ni1.55Si0.5C,Fe7Cr0.80Mn1.86V1.47Ni1.47Si0.8C,研究了这3种Fe基多元合金奥氏体基体的稳定性及平衡几何构型.计算结果表明:合金1的奥氏体基体最稳定,合金3的奥氏体基体最不稳定,最容易转变成马氏体,与X射线衍射结果一致.     

音频磁头用软磁合金的研制

对4Mo-79Ni 坡莫合会附加 Ti、W、V 和 Al 等元素所得合金的磁性能和机械性能作了研究。新合金之一,当成分为(wt%)1.98W、0.96Ti、0.57Mn、4Mo、80Ni,余 Fe 时,具有μ_1=4.13mH/m(0.10mm,10kHz),Hc=JA/m,B_8=0.666T,ρ=60μΩ·cm。得出了从成分上确保合金 B_8和ρ值的计算式。     

Ti38Zr45Ni17准晶合金的储氢性能及其V合金化

研究了三元Ti38Zr45Ni17准晶合金及其V合金化后的四元合金(Ti0.38Zr0.45Ni0.17)100-xVx(x=5%、10%、30%、40%、60%(原子分数))的吸放氢性能.准晶成分设计思想源自于团簇线方法,即在Ti-Zr-Ni三元合金体系中利用两条团簇线的交点确定最佳准晶成分Ti38Zr45Ni17.利用铜模吸铸快冷工艺制备直径为3mm的合金棒.吸放氢测试结果表明,Ti38Zr45Ni17准晶在303K首次吸氢量为0.9%(质量分数),在573K时合金首次吸氢量可达2.38%(质量分数),合金吸氢过程快速完成,并放出大量的热,可将吸氢前的粉末样品烧结成块体凝聚物.吸氢后准晶结构消失,完全转化为氢化物结构.添加5%～30%(原子分数)的V进行合金化时可提高合金在573K下的首次吸氢量,最大为2.96%(质量分数);具有固溶体结构的(Ti0.38Zr0.45Ni0.17)40V60合金在室温下首次吸氢量为3.2%(质量分数).由于准晶及其V合金化的合金在吸放氢之后均形成了稳定的氢化物,导致其放氢非常困难.     

Zr1-xTix(Ni0.6Mn0.3V 0.1Cr0.05)2(x=0～0.5)Laves相储氢合金的电化学性能

本文研究Zr1-xTix(Ni0.6 Mn0.3V0.1Cr0.05)2(x=0,0.1,0.2,0.3,0.4,0.5)系Lav es相储氢电极合金的气态P-C-T性能、晶体结构及电化学性能.XRD分析表明,Ti合金化使 Zr基储氢合金主相从C15相转变为C14相.当x>0.2时,第二相Zr7Ni10相消失, 并出现TiNi相.Ti合金化使Zr基储氢合金中C15相和C14相的晶格常数线性递减.气态P-C-T 测试表明,Ti合金化从x=0增加至x=0.5时合金的吸放氢平台压力升高约10倍,但降低了储氢合金的最大储氢容量.电化学测试表明,Ti合金化有利于改善Zr基储氢合金的活化性能, 这与Ti在KOH溶液中易于溶解有关,但过高的Ti含量降低了合金电极的循环稳定性.Zr1 -xTix(Ni0.6Mn0.3V0.1Cr0.05)2合金的电化学容量和高倍率放电性能均随合金中Ti含量的增加先上升后下降,这与合金的相结构组成有很大关系 .     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...