5A06铝镁合金温热环境变形机理的研究

目的获得5A06铝镁合金的本构方程及各向异性指数。方法在一定温度范围和不同应变速率下进行单向拉伸试验,获得了5A06-O铝镁合金板材不同温度不同应变速率下的真实应力-真实应变曲线及不同方向的厚向异性指数等关键参数,并结合当前关于各向异性屈服准则的研究,通过分析与计算得到了适合于5A06铝镁合金温热成形的Barlat2000各向异性屈服准则。结果获得了温度范围为150～300℃的5A06铝镁合金的本构方程,以及温度范围为20～300℃的5A06铝镁合金的各向异性系数α_1—α_8随温度的变化曲线。结论获得的5A06铝镁合金的本构方程及各向异性指数较为符合实验结果,可用于该材料温热成形的有限元模拟。     

纯钼薄板各向异性拉压不对称性本构建模研究

目的 对纯钼薄板的各向异性、拉压不对称性以及本构关系进行研究.方法 对纯钼薄板进行不同方向的单拉实验、中心带孔试样单拉实验,和纯钼薄板V形弯曲实验,同时结合有限元模拟反推材料力学性能以及对CPB06屈服准则及Swift强化模型进行参数标定,并进行模型可靠性验证.结果 纯钼薄板具有一定的面内各向异性、拉压不对称性以及显著...     

加工方式对AZ31变形镁合金热拉伸流变应力的影响

针对不同方法制备的AZ31镁合金薄板,利用热拉伸试验机和金相显微镜对其在不同温度和变形速率下的流变应力进行了实验研究.结果表明:挤压、交叉、热轧和冷轧等方法制备的AZ31镁合金薄板的应力-应变曲线基本特征是相同的.峰值流变应力随变形温度的升高和应变速率的降低而降低,在低温时具有明显的厚度效应;当温度大于350℃时峰值流变应力几乎不随板材厚度变化而变化;应变速率小于1.0×10-2s-1,变形温度大于150℃下所有AZ31薄板的延伸率均δ≥45%;单向轧制薄板的各向异性随温度提高减小.     

新型铝锂合金板材塑性流动与各向异性性能试验研究

通过单向拉伸试验,研究了新型Al-Li-Cu-Mg合金板材的基本成形性能.针对材料显著的各向异性性能,选取屈服强度、抗拉强度、延伸率以及厚向异性指数等材料性能参数进行对比分析,绘制了7个不同取样方向的单向拉伸曲线,研究了材料各向异性的规律.基于对本构方程、各向异性屈服准则的研究及对比,建立了新型Al-Li-Cu-Mg合金的本构模型,并根据实验曲线计算得到Hill48、Barlat89屈服准则中的各向异性参数,结合各屈服准则绘制了新型Al-Li-Cu-Mg合金屈服轨迹.对比分析各试件的断口方向,并结合第一、第三强度理论,分析了材料的各向异性.利用SEM观察试样的断口形貌,分析对比试件断口的韧窝特征及带状特征.研究发现:试件的延伸率越大,其韧窝特征越明显;反之,其带状特征越明显.从微观角度印证了Al-Li-Cu-Mg合金板材存在的各向异性.     

超细晶纯铝微塑性变形本构关系的建立

为了研究超细晶纯铝热变形行为,利用等通道挤压工艺制备了超细晶纯铝,并采用INSTRON 5965材料电子万能试验机对超细晶纯铝进行了高温微压缩实验,分析了超细晶纯铝在150~250℃、应变速率3.3!10-4~1!10-1s-1条件下流动应力的变化规律.研究表明,流动应力随试样尺寸的减小呈下降趋势,且变形温度和应变速率对流动应力有显著影响,流动应力随变形温度的升高和应变速率的降低而降低.基于双曲正弦形式修正的Arrhenius关系的本构模型,建立了超细晶纯铝高温微压缩变形本构关系.实验验证表明,所建立的本构关系能够较好地反映超细晶纯铝高温微塑性变形行为特征.     

AZ31B镁合金管材热态内压成形性能的研究

为了研究变形镁合金AZ31B管材的热态内压成形性能,通过单向拉伸测试了不同温度和应变速率下其力学性能的变化,通过胀形实验研究了温度对内高压成形性能的影响,以及相应变形条件下微观组织的变化.实验结果表明:在20～300℃时,AZ31B的屈服强度和抗拉强度随着温度的升高而降低,总伸长率随着温度的升高而提高,均匀伸长率随着温度的升高先增大后减小;当应变速率在0.001～0.1s-1时,屈服强度和抗拉强度随应变速率的增大而升高,总伸长率随着应变速率的增大而减小,均匀伸长率随着应变速率的增大先增加后减小;当温度在20～250℃时,镁合金管材的极限胀形率随温度的升高先增大后减小,在175℃时达到最大值.微观组织观察表明,175℃下不完全动态再结晶和孪晶两种微观组织的出现是使镁合金管材极限胀形率提高的主要原因.     

T6态7075铝合金温热下各向异性研究

对高强度铝合金7075-T6在0.03s-1应变率下,50～250℃温度范围进行系列单向拉伸试验,并测得不同温度下的厚向异性系数R。结果表明：7075-T6铝合金的流动应力随试验温度的升高而减小;在50～200℃温度区间,延伸率随温度的升高而增加;当温度为250℃时,由于T6特性的消失,延伸率反有所降低,得到最佳的成形...     

TC1钛合金板材热加工性能研究

目的 研究新一代飞机用TC1钛合金板材在不同温度和应变速率下的热塑性变形行为,进行热变形本构建模,构建热加工图。方法 在Gleeble-3500热模拟试验机上开展TC1钛合金板材在温度为500~650 ℃、应变速率为0.01~0.000 1 s^?1条件下的等温恒应变速率单向拉伸试验,利用应变补偿的双曲正弦模型进行热变形本构拟合,绘制热加工图。结果 在同一温度下,TC1钛合金的流动应力随应变速率的减小而降低,但伸长率增加,最大断裂应变增大;变形温度在500 ℃时,加工硬化占据主导地位,随着温度升高至550、600、650 ℃,硬化阶段变短,应力达到峰值后很快下降,发生软化,此时热软化占主要地位。结论 建立的应变补偿的双曲正弦本构模型能够有效描述TC1钛合金板材在不同温度和应变速率条件下的热塑性变形行为;根据建立的TC1钛合金板材热加工图,可以确定其热加工工艺窗口为600~650 ℃、0.000 1~0.001 s^?1,为TC1钛合金板的热加工提供科学指导。     

考虑摩擦效应的工业纯钛TA2热压缩变形本构方程及热加工图

目的 研究工业纯钛TA2在变形温度为800~950 ℃、应变速率为0.001~1 s^?1、压下量为50%条件下的热压缩变形行为,构建材料高温本构方程及热加工图。方法 利用Gleeble–3500热模拟试验机进行热压缩试验,对实测流变曲线进行摩擦修正,通过线性回归拟合等方法建立本构方程,基于动态材料模型构建工业纯钛TA2热加工图,确定材料最佳热变形区域。结果 工业纯钛TA2热变形激活能Q为473.491 kJ/mol,应力指数n为3.876 6;最佳热变形参数为变形温度850~950 ℃、应变速率0.02~0.35 s^?1。结论 工业纯钛TA2摩擦修正后的流变应力值均低于实测值,流动应力随变形温度的升高和应变速率的减小而降低。所建立的Arrhenius本构模型可较为准确地描述工业纯钛高温流变行为。工业纯钛TA2在中高温中等应变速率条件下加工性能良好,该区域材料发生了动态再结晶组织转变。     

6013-T4铝合金不同温度下的动态流变应力及组织演变

采用分离式霍普金森(SHPB)压杆装置进行6013-T4铝合金动态压缩试验,获得温度为25℃、100℃、200℃、300℃、400℃,应变速率为1 000s~(-1)、2 000s~(-1)、3 000s~(-1)、4 000s~(-1)、5 000s~(-1)条件下材料的真应力-真应变曲线,并通过透射电子显微镜(TEM)观测了6013-T4铝合金在不同变形条件下的组织演变。结果表明:6013铝合金有明显的温度敏感性,但是对应变速率的敏感性较弱。应变速率和温度对6013铝合金微观组织的影响显著,位错密度随应变速率的升高而增大,随温度的升高而减小。基于实验数据,求得了6013铝合金Johnson-Cook模型的本构参数并建立其本构模型。与实验结果进行对比,结果表明,所建立的本构模型能够很好地预测6013铝合金的流变应力。     

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.……     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

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.