TC8合金转子叶片锻造工艺研究

为研制一项TC8合金转子叶片,并达到提高锻造生产效率、降低生产成本的目的,进行了锻造工艺性试验、工艺参数试验,研究了TC8合金锻造工艺适应性以及加热温度、变形程度对低倍组织、显微组织及力学性能的影响.结果表明,TC8合金十分适合锻造工艺,采用较低的锻造加热温度能够获得初生α相含量更高的等轴组织,变形程度在40%以内所获得的组织均匀性较好.在此基础上,依据TC8合金转子叶片单榫头、小尺寸的结构特点,采用了高效的挤压制坯+终锻成形工艺,通过叶片锻造成形试验,试制出了具有均匀且状态理想的金相组织、良好表面质量的TC8合金转子叶片锻件,表明了所制定的叶片成形工艺及工艺参数合理可行.     

柴油机关键件精密成形工艺研究

目的提高柴油发动机关键件泵体铸改锻后的综合机械性能,采用精密成形技术来实现泵体的组织和性能的一致性控制。方法首先通过工艺分析,设计了锻件的形状及其分模方式,建立了锻件的三维实体模型;再根据其工艺方式,设计了模具结构及工艺路线,并对预制坯形状进行了设计。结果经过工艺试制,泵体锻件充型饱满,缺陷得到克服,尺寸精度达到了技术要求,泵体的流线连续,晶粒度达8级,经铸改锻后性能得到了大幅提升。结论通过工艺实验,分析了成形中缺陷产生的原因和控制方法,优化了预制坯设计以及成形关键工艺参数,为确定最终精密成形工艺提供了依据。     

钛合金双安装板静子叶片精锻成形工艺优化

为了缩短双安装板结构的TC4合金低压第二级静子叶片精锻工艺流程,并得到更优的金相组织、力学性能,首次将等温锻造方法引入叶片精锻工艺中,采用一火次等温预锻代替两火次普通预锻.利用刚粘塑性有限元法模拟等温预锻过程,分析了金属流动规律、应变场等的变化情况.结果表明,所成形的等温预锻件应力较低、应变分布比较均匀.经叶片成形工艺试验,得到了采用等温预锻的叶片精锻件,将采用普通预锻的叶片精锻件与之对比,发现采用等温预锻的叶片较采用普通预锻的叶片金相组织均匀性好,而两者的力学性能相当.     

1420铝锂合金模锻件锻造工艺的研究

利用高温变形实验,研究了1420铝锂合金在不同变形条件下的变形行为,获得合金的塑性图、变形抗力图、晶粒尺寸-变形程度关系图,确定出合金的锻造工艺参数:锻造温度为350～420℃,临界变形程度为8%～10%,变形速率以低速为宜.结合实际情况,制定出合理的、经济的1420铝锂合金模锻件成形工艺,即6000t水压机上多方锻开坯→车成锥体→8000t卧式挤压机上终压模成形.生产出的1420合金模锻件尺寸精度高,综合性能优良.     

基于响应面法的铝合金筋板锻件工艺参数多目标优化

为了能获得更好的铝合金筋板类锻件锻造成形工艺参数,提出了基于响应面法(Response Surface Methodology,RSM)和有限元模拟技术(finite element simulation,FEM)的锻造成形工艺参数多目标优化策略.以铝合金筋板类锻件晶粒均匀性和锻造变形力作为评价指标,建立了有限元数值模拟与响应面法相结合的二阶分析模型,求得的回归模型拟合度达89.59%.并运用MATLAB软件求出可行设计空间中目标函数最佳工艺参数组合为始锻温度465℃、锻造速度8.7 mm/s、摩擦系数0.2.锻件的晶粒均匀性有了很大的改善,同时有效的降低了锻件变形力,并通过DEFORM-2D模拟和热加工图对其进行了验证,表明了所提出方法的有效性.     

Ti–6Al–4V钛合金筋板类吊挂锻造成形工艺优化及模具磨损研究

目的 改善Ti–6Al–4V筋板类吊挂锻件成形缺陷,降低模具磨损。方法 通过对原始工艺中存在的折叠、充填不满等缺陷进行分析,揭示局部飞边高度对锻件充填的影响,进而优化终锻模具局部飞边高度;通过增加预锻件筋条等几何特征,对预锻模具结构进行优化设计,并分析塑性变形时筋条区域金属材料的流动情况。结合BP神经网络技术,分析锻造工艺参数对终锻模具磨损的影响,并对工艺参数组合进行优化设计。结果 基于局部飞边高度对锻件充填效果的影响规律,确定最佳局部飞边高度为4 mm;通过增加预锻筋条优化预锻件结构,从而有效避免折叠缺陷;将BP神经网络技术与数值模拟结合,得到了最优工艺参数组合,有效降低了锻造模具的磨损量。结论 通过实际锻造生产试验对模拟分析结果进行了验证,固化了最佳模具结构与工艺参数组合,获得了变形均匀且无工艺缺陷的钛合金发动机吊挂锻件。     

锻件锻后组织和性能的自适应预测

总结了锻造过程优化，变形工艺参数优化及锻件锻后的组织和性能预测的现状和发展趋势。作为今后的发展，提出了一种用模糊网络来建模来预测锻件锻后的组织和性能，并优化变形工艺参数。这对保证锻年质量，减少材料消耗，提高生产率有显著的优越性。     

铝合金控制臂辊锻制坯模锻工艺数值模拟

针对控制臂现阶段模锻成形工艺工序多,生产率低,劳动强度大等缺点,提出辊锻制坯一模锻成形工艺,设计辊锻制坯各道次的尺寸参数,用数值模拟代替物理试验预测金属成形过程。通过对控制臂辊锻成形过程的数值模拟,并对辊锻后坯料进行弯曲、终锻成形,获得较好的锻件,为指导此锻件的生产实践提供了理论依据。     

LC4铝合金呆扳手成形热力学参数的确定

通过试验研究了LC4铝合金呆扳手成形的温度、变形程度、变形速度、加热方式和加热速度等成形热力学参数与成形质量之间的关系.解决了试验过程中出现的一些问题,确定了最佳成形工艺参数为:始锻温度400～450℃、终锻温度350℃左右,第1阶段的变形量为30%～50%,第2阶段的变形量为75%.     

GH4169合金精锻叶片腐蚀条带组织的成因分析及预防措施

目的 分析精锻工艺成形的GH4169合金压气机转子叶片出现腐蚀条带组织的原因,以制定相应的预防措施。方法 对精锻叶片用GH4169合金开展锻造热过程模拟试验,采用电镜观察其显微组织,以判断叶片锻件异常组织与原材料组织的关联。采用数值模拟方法对锻造工艺参数,尤其是锻造变形量进行分析与验证,找出锻造工艺方案的不足之处。结果 当原材料存在δ相偏聚时,容易导致叶身及榫头部位出现纵向腐蚀条带组织;当叶片锻造变形设计不合理,盆弧侧、背弧侧的预锻件与终锻件的变形体积比超出1.1～1.4时,会导致榫头部位出现金属流动异常的现象,进而产生应变剪切带、导致叶片榫头部位出现异常组织。结论 在叶片精密锻造生产前要确保原材料组织均匀,不能出现δ相偏聚,同时采用数值模拟方法来合理控制锻造各阶段的变形量与应变场,确保叶片预锻件与终锻件的变形体积比合理、金属变形均匀,这样才能保证叶片叶身和榫头部位不出现腐蚀条带组织。     

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.     

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...     

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.     

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 ...