THE TRAPPING PHENOMENA OF HYDROGEN STUDIED BY THE ELECTROCHEMICAL PERMEA—TION TECHNIQUE AND THE DISCUSSION OF SEVERAL EXPERIMENTAL PROBLEMS

本文运用电化学渗透技术研究了18Ni 马氏体时效钢的氢扩散和捕集现象。结果表明,时效试样内存在析出相颗粒,使表观氢扩散系数减小,其原因是析出相界面捕集氢,阻滞了氢输运过程的进行;并发现500℃时效3h 表观扩散系数最小,扩散激活能最大,因为该制度时样品内析出相颗粒的数量最多,分布最弥散,此时的析出相界面捕集能为10.0kJ/mol,陷阱密度(室温时)为3.4×10~(26)/m~3。最后就常规双电解池式的电化学渗透实验,分析和讨论了几个值得注意的问题。     

电化学渗透法研究氢陷阱捕集现象及几个实验问题讨论

本文运用电化学渗透技术研究了18Ni 马氏体时效钢的氢扩散和捕集现象。结果表明,时效试样内存在析出相颗粒,使表观氢扩散系数减小,其原因是析出相界面捕集氢,阻滞了氢输运过程的进行;并发现500℃时效3h 表观扩散系数最小,扩散激活能最大,因为该制度时样品内析出相颗粒的数量最多,分布最弥散,此时的析出相界面捕集能为10.0kJ/mol,陷阱密度(室温时)为3.4×10~(26)/m~3。最后就常规双电解池式的电化学渗透实验,分析和讨论了几个值得注意的问题。     

65Mn钢氢陷阱参数的讨论

在电化学渗透法测量６５Ｍｎ钢五种显微组织陷阱参数的基础上，用陷阱参数分离法得到下贝氏体中位错的陷阱能为２８．１ＫＪ／ｍｏｌ；回火马氏体中孪晶应变场的陷阱能力７４．４ＫＪ／ｍｏｌ；挛晶和位错作为混合陷阱的陷阱能力４９．６ＫＪ／ｍｏｌ．     

奥氏体耐热钢Sanicro25蠕变行为和断裂特征

用OM、SEM和TEM等方法研究了超超临界电站用Sanicro25钢的蠕变机制。结果表明，这种钢的最小蠕变速率随着温度的升高和应力的增大而提高。根据最小蠕变速率特征得出表观应力指数为7.6～8.2，表观激活能为496.7～531.8 kJ/mol。在蠕变过程中在晶内弥散析出的纳米级Cu-rich相和MX相阻碍位错运动，导致蠕变门槛值应力的出现。用线性外延法求出的门槛值应力，随着温度的升高而减小。用门槛值将蠕变本构方程修正为■，可将不同温度下的最小蠕变速率归一化；同时确定真实应力指数(n=5)和真实表观激活能(Q=286.6 kJ/mol约等于γ-Fe自扩散激活能)，从而判别出实验参数下材料的蠕变机制为点阵自扩散协助的位错攀移。     

喷射沉积Al-3.3Fe-10.7Si合金的组织、韧性及内耗性能研究

利用喷射沉积工艺制备Al-3.3Fe-10.7Si合金坯,经挤压制成试样.研究了合金组织、韧性及内耗行为,得出该合金在60～250℃温度范围产生的内耗峰,是由于晶界滑动弛豫引起的,弛豫过程激活能为172.2kJ/mol.在内耗峰位置晶界滑动消耗部分振动能,合金韧性在此处出现极大值.     

Fe-Cr-Mo-W-V系热作模具钢高温热稳定性机理研究

采用硬度和扫描组织评价方法分析了三种Fe-Cr-Mo-W-V热作模具钢(DM、H21和H13)在580~650℃下的热稳定性,研究结果表明DM钢较H21、H13钢具有高的热稳定性。同时,通过测定三种钢的连续加热曲线并结合透射电镜组织,研究了高温热稳保温过程中存在的重要碳化物的类型。为了揭示Fe-Cr-Mo-W-V钢的热稳定机理,计算了三种钢由M2C型碳化物形成阶段向MC型碳化物形成阶段转变的临界点激活能,其值为163.9~204.1kJ/mol,表明M2C、MC型碳化物的形成不仅受体扩散影响,而且与位错管道扩散激活能相关,DM钢具有最高临界激活能,其值高达204.1kJ/mol。进一步对比三种钢中的价电子结构差异,得出最高热稳定性的DM钢具有最佳价电子结构。     

一种新型耐蚀高弹性合金—00Cr12Ni9Cu2TiNbBeRE马氏体时效不锈钢

本文对以00Cr12Ni9Cu2TiNb马氏体时效不锈钢为基,单一或复合加入微量铍和稀土元素的各炉钢进行了物理—机械性能和化学性能的测定,从而选定00Cr12Ni9Cu2TiNbBeRE钢为一种综合性能优良的新型耐蚀高弹性合金。通过超高压电镜、X—射线衍射仪、电子探针等对上述两种钢的组织结构进行了较深入地研究。两种钢的显微组织均为板条马氏体。00Cr12Ni9Cu2TiNb钢的析出相为棒状NiTi;而00Cr12Ni9Cu2TiNbBeRE钢的析出相为棒状NiTi及球状NiBe,且其时效激活能为155.5kJ/mol,比00Cr12Ni9Cu2TiNb钢要高6.3kJ/mol。     

7B04铝合金的超塑变形行为及其机理

在470～530℃、3×10~(-4)～1×10~(-2)s~(-1)条件下对7B04铝合金进行超塑拉伸,在530℃、3×10~(-4)s~(-1)的条件下得到了1663%的最大延伸率。计算结果表明,应变速率敏感性指数m的最大值为0.63。在不同初始应变速率条件下变形激活能Q的计算值分别为158.44 k J/mol、188.13 kJ/mol、177.78 kJ/mol和250.54 kJ/mol。建立7B04铝合金高温变形本构方程并绘制了R-W-S变形机理图。结合微观组织演变和计算结果,分析了超塑变形机理。结果表明,7B04铝合金的主要变形机理为晶格扩散控制、位错滑移协调的晶界滑动。     

马氏体冷轧-回火制备超细晶钢及其热稳定性

在低碳钢和低碳加铌、钒、钛微合金钢中,通过马氏体冷轧--回火的方法获得了尺寸为数百纳米的超细晶粒铁素体组织,研究了超细晶粒组的形成机制和热稳定性.通过马氏体相交在这些钢中引入了大量高密度位错,马氏体冷轧后位错进一步增殖,形成大量位错胞状结构;在500-600℃进行的60min回火将上述胞状结构转变成具有清晰大角晶界的超细晶粒.在回火过程中形成的微合金元素碳化物对位错运动和晶界移动具有有效的"钉扎"作用,有助于获得超细晶组织并明显提高其热稳定性.     

Ultrafine Grains Formed through Tempering Cold Rolled Martensite and the Thermal Stability Analysis

在低碳钢和低碳加铌、钒、钛微合金钢中,通过马氏体冷轧--回火的方法获得了尺寸为数百纳米的超细晶粒铁素体组织,研究了超细晶粒组的形成机制和热稳定性. 通过马氏体相变在这些钢中引入了大量高密度位错,马氏体冷轧后位错进一步增殖, 形成大量位错胞状结构;在500-600℃进行的60 min回火将上述胞状结构转变成具有清晰大角晶界的超细晶粒.在回火过程中形成的微合金元素碳化物对位错运动和晶界移动具有有效的“钉扎”作用,有助于获得超细晶组织并明显提高其热稳定性.     

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.     

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.     

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 ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.