冷轧态Al-Li-Cu-Mg-Zr合金的超塑变形工艺

研究了未经预处理的冷轧态 Al-Li 合金超塑变形工艺,根据三段拉伸设想,按正交试验设计方案,进行了超塑拉伸试验。结果表明:对于冷轧态 Al-Li 合金,采用三段拉伸工艺可以获得良好的超塑性,其延伸率达到550%以上,超过一段和两段拉伸。     

冷轧态Al—Li—Cu—Mg—Zr合金的超塑变形工艺

研究了未经预处理的冷轧态Ａｌ－Ｌｉ合金超塑变形工艺，根据三段拉伸设想，按正交试验设计方案，进行了超拉伸试验，结果表明，对于冷轧态Ａｌ－Ｌｉ合金，采用三段拉伸工艺可以获得良好的超塑性，其延伸率达到５５０％以上，超过一段和两段拉伸。     

热处理工艺对BT22钛合金组织和性能的影响

研究了两级退火工艺参数对BT22钛合金显微组织和室温拉伸性能的影响.研究发现:热处理后的显微组织为α+β的两相组织,晶粒形状较为规则,晶界上有连续和不连续的α相,晶内分布着点状、球状和短杆状的α相;BT22钛合金强度在830℃(T1)出现极大值,随着等温淬火温度(T2)的升高及时效温度(T3)的降低而增高,塑性的变化规律与强度相反;等温淬火的冷却方式(υ2)对合金的性能影响不大,BT22合金具有低速冷却的淬火性能,淬透性能极好.     

LY12合金形变时效强化的研究

本文研究了形变时效(淬火 室温预拉伸形变 时效和淬火 预时效 温形变 最终时效)对LY12合金的显微组织和常规机械性能的影响,分析了形变时效强化机制。结果表明,室温预拉伸形变可使LYl2合金强度提高,预时效(欠时效)十温形变 短时最终时效可使强度提高的幅度更大,但形变使塑性下降;细小弥散的析出相和高密度均匀分布的位错,以及两者的交互作用是形变时效强化的主要原因。     

铍青铜淬火及时效的显微组织

铍青铜是优良的弹性合金,其显著特征是在淬火后具有高的塑性,能制成各种形状的弹性元件,经时效后强度、硬度、弹性明显提高,而且弹性滞后小,弹性稳定。本厂显示记录仪表的滚子簧片等仪表弹性元件均采用铍青铜带材制成。仪表弹性元件的弹性性能及其稳定性是影响仪表的显示和记录精度的重要因素之一。由于本厂选择了较合理的淬火以及时效热处理工艺,获得比较理想的淬火组织及时效组织,保证了弹性元件的良好性能。本文分析本厂所用铍青铜带材淬火及元件时效的显微组织,并讨论了显微组织与性能关系。     

形变热处理对低浓度CuCr合金性能的影响

用两种形变热处理工艺制备了Cu-0.4Cr合金,并通过测定不同工艺合金的硬度和电导率,研究了形变热处理工艺对合金性能的影响,以得到硬度和电导率综合性能优异的且适宜工业化批量生产的工艺.结果表明,CuCr合金在线热轧淬火后经60%冷轧并在450℃时效30min后其硬度和电导率分别为156Hv,86.4%IACS,该工艺适合工业化批量生产;经固溶一冷轧80%-450℃时效30min后,合金硬度和电导率可达176Hv,80.2%IACS,虽然该工艺所制备合金性能优异,但难以实现工业化批量生产.对所得结果分析表明,所制备CuCr合金极易过时效,且冷轧变形量越大,时效温度越高,合金过时效越明显,生产中难以控制.微合金化以延缓时效是该合金值得研究的方向.     

Cu-15Ni-8Sn及Cu-15Ni-8Sn-0.2Nb Spinodal分解型弹性合金的研究

研究了形变时效和淬火时效对含 Nb 和不含 Nb 的两种 Cu-15Ni-8Sn spinodal 分解型合金的力学性能、应力松弛性能和其他物理性能。经56%形变、400℃时效30min 能使这两种合金获得很高的强度(σb～1400MPa,σ_(0.2)～1300MPa)和弹性模量(E～140,000MPa);在200℃具有良好的抗应力松弛性能;加 Nb 的合金能改善250℃的抗应力松弛性能。淬火时效处理能获得适中的强度(σ_b900～950MFa,σ_(0.2)630～650MPa)和极良好的延性(δ～20%);加 Nb 能加速 spinodal分解,提高时效初期的强度。淬火时效态的两种合金在250℃下均显示良好的强度和弹性的稳定性,十分适合用作高温导电弹性材料。对调幅组织的强化和 Nb 的作用进行了讨论。     

热轧水冷Cu-Ni-Si合金的时效与冷轧工艺改进

研究了时效对不同状态Cu-3.2Ni-0.75Si-0.3Zn合金性能的影响,发现时效冷轧产生的高密度位错在时效初期和后期对溶质原子的析出分别起着促进和抑制两种相反的作用.对热轧水冷 60%冷轧合金的时效及冷轧工艺进行了正交试验.结果表明,各因素对电导率和显微硬度影响程度的主次顺序分别为:时效温度＞时效时间＞时效后冷轧量,和时效温度＞时效后冷轧量＞时效时间.对热轧水冷并60%冷轧合金直接进行适当的时效和冷轧工艺,可以获得和合金固溶 时效后相当的性能,为生产中省去固溶工艺提供了参考依据.     

热处理制度对含Zr的Al-Zn-Mg-Cu系合金组织与性能的影响

本文系统研究了热处理制度(包括单级时效、不同温度和时间组合的双级时效、分级淬火)对含Zr的Al—Zn—Mg—Cu系合金显微组织和力学性能的影响。结果表明,预时效+150℃/24h终时效的双级时效工艺具有比传统的峰值时效工艺T6和其它双级时效工艺更高的强度和塑性。通过对透射电镜薄膜样品的组织观察,分析了分级淬火及时效过程中合金的沉淀析出行为及ZrAl_3相对沉淀过程的影响。     

Ti-15-3钛合金超塑行为研究

为系统了解Ti-15-3合金的超塑性,研究了固溶态和两种不同变形量冷轧态的Ti-15-3合金板材在700～800 ℃和1×10-4 ～3×10-3s-1应变速率范围内的超塑性行为.结果表明:Ti-15-3合金具有较好的超塑性能,冷轧态合金的延伸率均优于固溶态,且随着板材冷轧变形量的增大而增大;各应变速率下,该合金都在780 ℃时获得最大延伸率和应变速率敏感性指数.在780 ℃和1×10-4s-1条件下拉伸时,冷轧变形量为52%的Ti-15-3合金板材获得了370%的延伸率,m值为O.56;变形温度和速率对合金的超塑性能影响很大,合金的延伸率在730～780 ℃范围内随温度的升高和应变速率的降低而升高,合金的流变应力则随之下降.     

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.……     

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.     

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.     

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 ...