AZ10镁合金均匀化退火工艺研究

通过金相组织分析、显微硬度测试和热压缩实验,研究了不同退火温度和时间条件下AZ10镁合金铸坯的显微组织、显微硬度、热压缩变形抗力以及变形能,分析了退火温度和时间对铸坯组织转变、成分均匀化、变形抗力和变形能的影响.结果表明,退火温度对均匀化起主要作用,AZ10镁合金铸锭的均匀化退火的优化工艺为400 ℃×18 h.     

AZ61镁合金的均匀化处理

研究了不同退火温度和时间条件下AZ61铸态镁合金的显微组织以及硬度值,分析了温度和保温时间对组织转变和成分均匀性的影响.得出温度是影响均匀化进程的主要因素,并推荐AZ61铸态镁合金的退火工艺为400 ℃×12 h.     

退火工艺对 AZ61镁合金铸坯组织及加工性能的影响

研究了均匀化退火对AZ61半连续铸锭的组织及变形性能的影响.通过组织观察、显微硬度测量以及在1500D Gleeble实验机上进行热压缩并计算变形能,分析比较了均匀化温度和时间对坯料组织和变形性能的影响.结果表明:均匀化退火有利于消除铸态组织中的枝晶偏析,不同均匀化退火工艺对第二相化合物的存在方式存在影响;AZ61镁合金硬度值随着退火温度的升高呈降低趋势;退火温度越高,AZ61镁合金热变形峰值应力大小随保温时间的波动逐渐变大;AZ61镁合金优化的退火工艺参数为400 ℃×12 h.     

铸态镁合金组织和力学性能研究

对Mg-5．0Y-3．0Nd-0．5Zr镁合金进行熔铸和不同温度的均匀化退火。测试该合金的室温拉伸力学性能。并采用金相显微镜,扫描电镜等方法观察铸态和均匀化退火态组织。结果表明,添加稀土元素能使镁合金的铸态组织得到细化,Nd和Y分别以Mg4、Nd3和Mg24Y化合物形式存在,均匀化退火后,试验合金抗拉强度和伸长率得到提高．其中450℃的均匀化退火效果最好,合金的抗拉强度比铸态时的提高了18．6％,塑性提高了3．5％。     

Al含量及均匀化处理对AZ系列镁合金组织的影响

为了在挤压生产中获取均匀的镁合金变形组织,需要掌握合金含量及均匀化退火对热挤压组织的影响规律.本实验通过在Gleeble-1500D热模拟实验机上对不同Al含量的AZ10,AZ31,AZ61和AZ91镁合金进行热模拟挤压,结果表明,经过400℃/12h均匀化退火,AZ10和AZ31合金均形成单一的α固溶体,AZ61合金...     

Ce和均匀化对Mg-2.0Zn-1.0Mn镁合金组织和性能的影响

在Mg-2.0Zn-1.0Mn镁合金中添加稀土Ce进行均匀化和挤压实验,分析稀土Ce和均匀化对ZM21镁合金组织和性能的影响规律。结果表明,添加稀土Ce可以有效细化ZM21合金的晶粒,提高ZM21镁合金的力学性能,降低ZM21镁合金凝固过程中的潜热和凝固温度范围。均匀化退火对ZM21镁合金挤压制品的性能和组织影响较小,但对ZM21+Ce镁合金的性能和组织影响明显,两种合金的断口均为混合型断裂,其中ZM21+Ce镁合金倾向于韧性断裂。     

均质化制度对Mg-Li合金显微组织和机械性能的影响

研究了超轻镁锂变形合金热处理后的合金显微组织和机械性能。镁锂合金在室温条件下具有非常良好的延展性，Mg—Li—Zn系变形镁合金铸锭经不同温度、时间均匀化退火后的组织、硬度以及冷轧性能进行了研究。结果表明。Mg．9％Li-2％Zn-2％Ca合金在573K温度均匀化退火12h后合金铸锭组织均匀；而对于Mg-9％Li-2％Zn合金，523K温度均匀化退火24h后组织较好。     

轧制ZK61镁合金板材晶粒长大行为

通过对热轧的ZK61镁合金板材试样分别进行不同温度和不同保温时间的退火实验,利用金相显微镜(OM)观察显微组织,对晶粒尺寸进行分析和处理,并建立数学模型,系统研究了轧制ZK61镁合金的晶粒长大行为。研究结果表明,晶粒尺寸随着退火温度的升高与退火时间的延长而粗化,退火温度对晶粒长大的影响比退火时间的影响明显。对于ZK61镁合金在250~450℃温度区间的晶粒长大过程,其晶粒尺寸与加热时间的关系可用Beck方程D~n-D_0~n=kt描述,其中k=k_0exp[-Q_g/(RT)]。计算可得晶粒长大指数n为3.5,长大激活能Qg为45kJ/mol。     

铸态ZK51镁合金的显微组织及其阻尼行为

研究了铸态ZK51镁合金的显微组织及其阻尼行为.结果表明,铸态ZK51镁合金显微组织由α-Mg及少量分布在晶界或晶内的Mg7Zn3相组成.室温下,铸态ZK51镁合金的阻尼值随振动频率变化不明显,只随应变振幅的增大而明显增大.在高温200℃条件下,材料阻尼性能随振动频率的增加而呈现指数下降趋势.铸态ZK51镁合金在280℃附近出现热激活弛豫阻尼峰.合金的阻尼行为可采用Granato-Lücke位错阻尼理论解释.     

退火工艺对AZ31镁合金微观组织的影响

研究了不同退火工艺下AZ31镁合金的微观组织.结果表明,退火温度在200～350℃,保温时间在30～120min时,AZ31镁合金横向和纵向显微组织变化基本一致;退火温度为300℃,保温120min后晶粒度均达到最小值,横截面最小晶粒度约为11.51μm,纵截面最小晶粒度约为12.85μm.分析了晶粒度随退火温度和保温时间的变化情况.     

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.     

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.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to