高温持久试验机测控系统

根据GB／T2039－1997《金属拉伸蠕变及持久试验方法》对高温持久试验的要求,对高温持久试验设备进行控制系统的设计和软件的开发,系统采用智能仪表完成对加热炉温度的检测和控制,利用组态软件自主开发应用程序,可在上位机上对16台持久试验机进行集中操作管理,实现了对高温持久试验全过程的计算机操作和监控。     

国产T92钢高温持久过程中的显微组织演变

对某国产T92钢进行了620,650,700℃三个温度下不同时间的高温持久试验和显微组织观察试验。结果表明:在620,650℃时,随着持久试验时间的延长,T92钢基体显微组织仍保持板条状马氏体形貌特征,碳化物析出数量不断增加,尺寸也有所长大,且持久试验达到一定时间后晶界会产生微孔洞;在700℃长时间高温持久试验后,T92钢基体显微组织板条状马氏体形貌特征消失,且晶界碳化物粗化严重。     

δ铁素体对ZG1Cr10MoWVNbN耐热钢持久强度的影响

通过对不同淬火温度的ZG1Cr10MoWVNbN耐热钢试样进行高温蠕变持久试验和金相分析,研究了δ铁素体对其持久强度的影响。结果表明:该耐热钢中的δ铁素体呈带状分布,降低了马氏体基体的连续性,使得该钢持久强度下降,并且δ铁素体含量越高,试样持久试验时间则越短;同时由于δ铁素体中固溶了大量合金元素,降低了马氏体基体中的合金元素含量,减弱了马氏体耐热钢的固溶强化和沉淀强化作用,这也会降低该钢的高温持久强度。     

SUS347奥氏体钢高温损伤的试验研究

对SUS347奥氏体钢持久强度试验后的试样进行了金相分析,探讨了高温损伤与持久强度之间的关系。分析结果表明,试验钢的高温损伤度随着温度的升高而上升,而持久强度则随着高温损伤度的增加而减小。这一关系的确立,为从微观角度研究奥氏体钢的蠕变损伤提供了一种判断依据。     

民用航空发动机150 h持久试验技术

150 h持久试验是型号研制必不可少的试验环节,也是适航条款明确规定的强制要求,深受适航当局的关注。该文对民用航空发动机150 h持久试验试车进行仔细分析和深入研究,针对需求逐层级分解,获取关键技术点,在试验试车过程中结合台架进行适应性改造,落实发动机三红线实现技术、台架推力修正技术以及等效试车谱制定技术,为完成持久试验试车奠定了坚实的技术基础。     

GH864合金在超温条件下碳化物含量与持久强度的关系

采用物理化学相分析、X射线衍射、金相检验和持久试验等分析方法研究了烟汽轮机叶片合金（GH864）在不同超温试验条件下显微组织中的碳化物含量与持久强度的关系。结果表明：随着GH864合金中碳化物含量的增加,尤其是M23C6量的增多,其持久强度下降,从而缩短了其剩余寿命。     

Ti40钛合金的持久寿命及其预测方法

通过高温持久试验对不同温度下Ti40钛合金的持久寿命进行研究,建立了Ti40合金的持久强度曲线。结果表明:在较低应力水平下,Ti40合金的持久寿命随应力增加而损耗的程度较为严重。同时,采用等温线外推法预测Ti40合金的持久寿命,预测结果表明:在500℃,310MPa条件下Ti40合金的持久寿命为828.80h,其置信度可达99.94%,该数据可为航空发动机的设计与选材提供参考依据。     

甲醇裂解气氛保护加热中氢脆的研究方法

通过对圆柱光滑试样的缓慢拉伸试验以及对圆柱缺口试样和预裂纹紧凑拉伸试样的静载持久试验,研究了40CrMnSiMoVA钢经甲醇裂解气氛保护加热后的氢脆倾向,通过分析和比较试验结果,得出预裂纹紧凑拉伸试样的静载持久试验适宜研究此类氢脆的结论,并讨论了在无法精确测定氢含量时对氢脆倾向定量考虑的方法。     

持久强度试验数据处理

持久强度试验数据处理的传统方法有等温直线法和Larson-Miller法。等温直线法需在每个试验温度下建一个方程,比较繁琐,Larson-Miller法需要商榷,为此开发了多元回归法。多元回归法是利用温度、断裂时间和应力之间的统计关系建立多元回归方程,用方程预测持久强度的方法。多元回归法预测持久强度的误差小、精度高;可进行温度和时间的外推预测;不需计算对数或使用对数坐标,方便直观。     

铝圆筒持久强度试验

鉴于用户对铝圆筒持久性能测定的高可靠性要求,却因无法制取满足国标要求的持久强度试验的试样而无法对其进行测试,因此专门设计并制造了一套铝圆筒持久强度试验台(专利号01101063.O),对成品铝圆筒进行持久强度测试.结果表明:外推得到95%置信度下铝圆筒在40℃服役10 a(年)的持久强度σ1040=(399±18)MPa.铝圆筒的持久性能可以满足用户要求.     

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 ...