Zn-10Al-2Cu合金高温热压缩流变行为研究

采用Gleeble-3800热模拟试验机对Zn-10Al-2Cu合金在变形温度为150~330℃、变形速率为0.01~10s-1条件下的流变行为进行研究。结果表明:Zn-10Al-2Cu合金在热压缩变形中,当应变速率一定时,流变应力随变形温度的升高而减小;而当变形温度一定时,流变应力随着变形速率的增大而增大,达到峰值后下降趋势平缓。Zn-10Al-2Cu合金的热压缩流变行为可用双曲正弦形式的本构方程来描述。在本实验条件下,该锌铝铜合金热变形应力指数n为5.4、热变形激活能Q为137kJ/mol,高温流变应力用含Zener-Hollomon参数的Arrhenius方程描述为:σ=123ln{(Z/(1.22×1013))1/5.4+[(Z/(1.22×1013))2/5.4+1]1/2}。     

ZK60镁合金的热压缩变形行为

采用Gleeble-1500热模拟机在温度250～400℃、应变速率0.001～1s-1、最大变形程度105%的条件下对ZK60镁合金进行了高温压缩模拟实验研究。分析了实验合金在高温变形时的流变应力和应变速率及变形温度之间的关系,计算了变形激活能和应力指数,并观察了热压缩变形过程中组织的变化。结果表明,合金的峰值流变应力随应变速率的增大而增加,随温度的升高而减小;在给定的变形条件下,计算出合金的变形激活能为63～130kJ/mol,应力指数为2.78～3.79;降低变形温度和提高应变速率可使再结晶晶粒的平均尺寸减小。     

BFe10-1-1铜合金热压缩流变应力行为

BFe10-1-1合金管是制造冷凝器的关键材料,主要采用热挤压方法成形.为了制定该合金的热挤压工艺,并为其挤压成形的数值模拟分析提供热力学参数,在Gleeble-1500动态热模拟机上进行高温等温压缩试验,研究了BFe10-1-1合金在高温塑性变形过程中的流变应力行为.试验温度为800~950℃,应变速率为0.1~20 S-1.研究结果表明,BFe10-1-1合金的流变应力随变形温度的增加而减小,随应变速率的增大而增大;随着应变速率越大,动态再结晶软化现象更为明显;获得了采用Zener-Hollomon参数来描述的BFe10-1-1合金高温变形的峰值应力方程,计算获得该合金变形激活能Q为182.68 kJ/mol.     

Cu-Ni-Si-P合金动态再结晶研究及组织转变

在Gleeble-1500D热模拟试验机上,对Cu-2.0Ni-0.5Si-0.03P合金进行高温压缩实验,应变速率为0.01～5s-1、变形温度为600～800℃,对其高温等温压缩流变应力行为进行了研究.研究结果表明:随变形温度升高,合金的流变应力下降,随应变速率提高,流变应力增大.在应变温度为750、800℃时,合金热压缩变形流变应力出现了明显的峰值应力,表现为连续动态再结晶特征.可采用Zener-Hollomon参数的双曲正弦函数来描述Cu-2.0Ni-0.5Si-0.03P合金高温变形时的流变应力行为.从流变应力、应变速率和温度的相关性,得出了该合金高温热压缩变形时的应力指数n,应力参数α,结构因子A,热变形激活能Q和流变应力方程.合金动态再结晶的显微组织强烈受到变形温度的影响.     

7075Al/SiCp复合材料的热压缩变形流变应力和组织行为

采用圆柱试样在Gleeble-1500热模拟机上对喷射沉积7075Al/SiCp复合材料进行高温压缩变形实验,实验条件为:变形温度300～450℃,应变速率0.001～1s-1.结果表明:7075Al/SiCp复合材料的流变应力大小受到变形温度和应变速率的强烈影响,流变应力随应变的增加而逐渐增加,出现一峰值后逐渐下降;流变应力随变形温度的升高、应变速率的降低而降低.可用Zener-Hollomon参数的双曲正弦形式来描述7075Al/SiCp复合材料高温压缩变形流变应力.随着变形温度的升高和应变速率的降低,7075Al/SiCp复合材料热变形过程中SiCp的分布逐渐均匀化,有利其热加工性能的改善.     

Mg-10Gd-3Y-0.6Zr-1Ag镁合金热压缩变形行为研究

为了考察Mg-10Gd-3Y-0.6Zr-1Ag镁合金在不同条件下的变形行为,采用Gleeble2000热模拟机对该合金进行研究,分析了该合金在变形温度350~500℃,应变速率0.001~1 s-1条件下流变应力的变化规律.研究结果表明:变形温度和应变速率对流变应力有显著的影响,流变应力随变形温度的升高和应变速率的降低而降低;在应变速率相同的情况下,合金在较高温度下变形时,流变应力随应变量的增加达到峰值后,基本呈稳态流变特征;采用双曲正弦模型计算出该合金的变形激活能和应力指数,建立了该合金相应的热变形本构关系.     

Cu-2.32Ni-0.57Si-0.05P合金热压缩变形研究

在Gleeble-1500D热模拟试验机上,对Cu-2.32Ni-0.57Si-0.05P合金在应变速率为0.01～5s-1、变形温度为600～800℃、最大变形程度为60%条件下,进行恒温压缩模拟实验研究.分析了实验合金在高温变形时的流变应力、应变速率及变形温度之间的关系,研究了变形温度对合金显微组织的影响.计算了合金高温热压缩变形时的应力指数n、应力参数α、结构因子A以及平均热变形激活能Q.结果表明:合金的流变应力随变形温度升高而降低,随应变速率提高而增大.热变形过程的流变应力可用双曲正弦本构关系来描述.当变形温度高于750℃时,合金流变曲线呈现出明显的动态再结晶特征,合金显微组织为完全的动态再结晶组织.合金的热加工宜在应变速率为0.1～1s-1、温度为700～800℃范围内进行.     

Cu-Cr-Zr-Ce合金高温热变形行为研究

Cu-Cr-Zr系合金是一类高强度高导电集成电路用引线框架铜合金。在Gleeble-1500D热模拟实验机上,采用等温压缩实验研究了Cu-Cr-Zr-Ce合金在变形温度为600～800℃、应变速率为0.01～5s-1条件下的流变应力的相互变化规律,测定了其真应力-应变曲线,并利用光学显微镜分析了合金在热压缩过程中的组织演变规律。结果表明,Cu-Cr-Zr-Ce合金的真应力-真应变曲线呈现典型的动态回复特征,其流变应力和峰值应力随变形温度的降低和应变速率的提高而增大;且变形温度越高,应变速率越小,合金越容易发生动态回复和再结晶。在上述实验基础上,基于流变应力、应变速率和温度的相关性,计算出了该合金热压缩变形时的热变形激活能Q,并建立了其等温压缩塑性变形过程的流变应力与变形温度和应变速率之间关系的本构方程。     

β21S钛合金高温变形行为研究EI北大核心

在Gleeble-1500热模拟试验机上对β21S钛合金进行了高温恒应变速率压缩实验,研究其在变形温度为750～1100℃,应变速率为0．01～1s^-1条件下的流变应力及微观组织变化规律,计算了变形激活能及应力指数,并给出了流变应力的计算模型。结果表明：合金的流变应力随应变速率的增大而增大,在恒应变速率下,其应力水平随温度的升高而降低;在较低温度和高应变速率变形时,合金仅发生回复现象,随着温度的升高和应变速率的降低,有部分再结晶发生且再结晶程度逐渐增大;计算得出实验条件下的变形激活能和应力指数分别为211．04kJ／mol和4．0129。     

ZK60镁合金热压缩变形行为

为了研究ZK60镁合金的热变形行为,采用Gleebe-1500热模拟机在变形温度为423～673K、应变速率为0.001～10s-1条件下对合金进行的热压缩试验.分析合金流变应力与应变速率、变形温度之间的关系,通过引入Z参数建立合金流变应力本构方程,并观察合金变形过程中的显微组织演变.结果表明:变形温度低于473K且应变速率大于0.1s-1时试样发生宏观开裂;在变形温度较高和应变速率较低时,合金真应力-真应变曲线具有动态再结晶特征.随变形温度升高和应变速率的降低流变应力减小,热压缩后的组织中再结晶现象越明显;应变速率越高,再结晶晶粒越细小.     

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.……     

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...     

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.……     

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.     

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