铝基复合材料的超塑性EI

采用新型的喷雾沉积法制备了１０ｖｏｌ％ＳｉＣｐ／ＬＹ１２铝基复合材料，并进行超塑性变形研究。结果表明：喷雾沉积法制备的铝基复合材料晶粒细小、组织均匀、致密，所以微观结构较好；该材料经热等静压和等温热正挤压后，具有良好的超塑性；该复合材料超塑性变形时的最佳条件是变形温度为４８０℃和初始应变速率为１．０×１０－３ｓ－１此时的应变速率敏感性指数为０．５３，最大延伸率为３４５％。     

冷轧态SiCp/LY12复合材料超塑性及变形机制

研究了冷轧态ＳｉＣ颗粒（ｄｐ＝１０μｍ）增强ＬＹ１２复合材料（ＳｉＣｐ／ＬＹ１２）的超塑性,着重探讨了变形机制。研究表明：（１）在温度Ｔ＝８０３Ｋ（比熔点高２６Ｋ）,初始应变速度ε０＝４．８×１０＾－４ｓ＾－１时,应变速度敏感系数ｍ值为０．４９,延伸率达２４０％;（２）超塑性变形后的晶粒尺寸约为１０μｍ;（３）该事材料超塑性变形的主要机制是晶界液相和基体中动态回复调节的但却受界面液相和界面扩散流释     

压力浸渗SiCW/LY12复合材料的超塑性

对压力浸渗、小挤压比挤压以及进一步扎制制备的β－ＳｉＣ晶须增强ＬＹ１２铝基复合材料的超塑性变形行为进行了研究。研究表明：该复合材料在温度７８８￣８０８Ｋ、初始应变再率为３．３×１０＾－３￣３．３×１０＾－２ｓ＾－１的条件下超塑性变形时,延伸率为２００％￣３７０％。     

30CrMnSiA钢的恒温相变超塑性

本文研究了７１０－８４０℃之间的３０ＣｒＭｎＳｉＡ钢的恒温超塑性。重点测试了在共析转变点Ａｃｌ点附近的超塑性指标。研究结果表明，３０ＣｒＭｎＳｉＡ钢具有恒温相变超塑性特性，在Ａｃｌ点温度附近材料延伸率有明显增长，流动应力最低。当初始应变速率为４．２×１０＾－４ｓ＾－１时，经预先调质处理的３０ＣｒＭｎＳｉＡ钢最大延伸率为６０８％，最低流动应力为５５ＭＰａ，与７１０－７４０℃温度区间内的研究结果相比延     

喷雾沉积法制造的铝基复合材料的超塑性

喷雾沉积法制造的SiC_P/LY12复合材料经热压和热正挤压后,晶粒得以细化,SiC_P分布的均匀性大大改善.超塑性拉伸试验结果表明:SiC_P/LY12复合材料具有超塑性;变形温度、应变速率对极限延伸率和应变速率敏感性指数m值均有较大的影响.在变形温度为500℃和初始应变速率为1.0×10-3s-1时,获得的极限延伸率为345%.      

缺口状态对SiC／LY12复合材料短纹疲劳行为的影响

研究峰值时效状态下ＳｉＣ／ＬＹ１２复合材料及ＬＹ１２铝合金不同缺口状态下的敌裂纹扩展行为，结果表明：在尖缺口及钝缺口状态下，短裂纹扩展的均表现为“马鞍”型特征；尖缺口下，ＳｉＣ不利于材料疲劳性能，钝缺口下，ＳｉＣ有利于材料疲劳性能，用闭合效应和缺口根部塑性区大小解释了缺口状态对短裂纹扩展的影响。     

SiC颗粒增强铝基复合材料冲击拉伸力学性能的试验研究

对ＳｉＣ颗粒增强铝基复合材料在应变速率为１５０～１０００ｓ＾－１范围内的冲击拉伸力学性能进行了试验研究，得到了材料从弹塑变形直至断裂的完整的应力应变曲线，结果表明ＳｉＣ颗粒增强铝基复合材料是一种应变率敏感材料，随着应变速率的提高，材料的屈服应力，破坏应力以及破坏应变均为相应提高，断口分析表明，ＳｉＣｐ／Ａｌ的破坏形式的比较复杂，是一种颗粒的脆性破坏与铝合金基体的韧性破坏共存，强界面与弱界面共存的混     

SiCw／6061A1复合材料温度循环拉伸变形行为

本文采用热循环拉伸试验方法研究了ＳｉＣｗ／６０６１Ａ１复合材料的变形行为．结果表明，ＳｉＣｗ／６０６１Ａ１复合材料温度循环拉伸变形行为与蠕变类似分为初始变形阶段、稳态变形阶段和快速断裂三个阶段；温度循环拉伸变形稳态流变速率明显提高；温度循环拉伸变形的应力指数低于恒温蠕变的应力指数．     

温轧态2618A铝合金高应变速率超塑性的研究

对温轧态２６１８Ａ铝合金在不同温度（４７０～５５０℃）和应变速率为１０￣（－３）～１０￣（０）ｓ￣（－１）范围内的超塑性进行了研究，确定了最佳超塑性变形规范：在５００～５３０℃温度范围内，应变速率为２．８×１０￣（－１）ｓ￣（－１）的条件下，可获得大于２３０％的延伸率，表明该合金具有高应变速率超塑性的特性。     

SiCp／202Al复合材料的超塑性能及断口形貌

熔铸法（ＩＭ）制备的ＳｉＣ颗粒（１４μｍ）增强２０２４Ａｌ复合材料经轧制成材后，在４９０、５１０、５２０和５３０℃，初始应变速率在１．６７￣１０＾－４￣１．６７×１０＾－３ｓ＾－１的范围内进行了超塑拉伸试验。结果表明，在５２０℃、初始变速速率为８．３３×１０＾－４ｓ＾－１，超塑延伸率最大，为２９０％，ｍ值约为０．４９。同时，利用扫描电镜观察断口形貌，分析了变形机理。     

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.