某空压机曲轴断裂失效分析

某空压机曲轴在车辆行驶过程中于轴颈圆角处发生断裂。通过宏观分析、扫描电镜分析、金相分析、圆角表面粗糙度测试以及硬度测试等方法对空压机曲轴的断裂原因进行了分析。结果表明:曲轴断裂为低应力下的高周疲劳断裂;裂纹起源于轴颈与轴肩圆角过渡处的加工刀痕,经疲劳扩展后发生断裂;曲轴断裂的根本原因是圆角处加工刀痕粗大,表面粗糙度不满足加工标准要求,应力集中严重,以及曲轴基体硬度偏低。最后针对曲轴断裂失效原因,提出了相应的改进建议。     

柴油机曲轴断裂分析

某6缸发动机曲轴在运行20000km后,从第七主轴颈与第六连杆颈之间的截面处断裂.对断裂曲轴进行了断口观察、化学成分分析、金相组织和力学性能检验.结果表明,曲轴属弯曲疲劳断裂,疲劳裂纹的主源位于第七主轴颈圆角过渡处.通过对相关件作进一步的调查分析,找出了曲轴断裂失效的原因,并提出了改进措施,取得了效果.     

汽车发动机曲轴断裂失效分析

某厂生产的发动机曲轴在用户使用过程中,3个月内共发生了4起曲轴断裂失效事故,采用化学成分分析、金相检验、硬度测试以及断口的宏、微观形貌分析等方法对断裂曲轴进行了分析。结果表明：曲轴断裂为高周低应力弯曲疲劳断裂,导致其断裂的主要原因是在曲轴第一曲拐过渡圆角R附近的曲柄表面聚集分布着机加工刀痕,形成了应力集中;在用户行驶过程中因车况、路面等复杂因素形成的过载或冲击载荷等作用下,在第一曲拐轴颈尺附近曲柄表面应力集中的机加工刀痕处萌生疲劳裂纹,并逐步扩展直至断裂失效。     

汽车曲轴断裂原因

某汽车曲轴在进行耐久测试时发生断裂。采用宏观观察、化学成分分析、扫描电镜分析和金相检验等方法，对该曲轴的断裂原因进行了研究。结果表明：该曲轴的断裂性质为疲劳断裂，裂纹起源于过渡R处的表面，R处尺寸偏小以及车刀加工纹路较深，增大了R处的应力集中，在运行时，R处萌生裂纹，在交变载荷的作用下，裂纹发生疲劳扩展，最终导致曲轴断裂。     

汽车发动机曲轴断裂失效分析

采用断口分析、显微组织检验、低倍组织检验、能谱分析和化学成份分析等方法对某汽车发动机曲轴断裂进行了失效分析,判断断裂失效的主要原因是非金属夹杂和次表面的原始微裂纹,建议改进热处理工艺,保证组织的均匀性,选用非金属夹杂物含量小的钢材。     

柴油机曲轴早期断裂分析

采用宏观断口分析、化学成分分析和显微组织检验等方法对增压柴油发动机曲轴发生断裂的原因进行了分析。结果表明,曲轴材质符合技术要求,而热处理后的校直过程存在问题,由此留下了隐患,造成该曲轴在运行过程中产生疲劳裂纹而断裂。提出了改进措施,杜绝了此类事故的发生。     

某地铁受电弓拉杆球铰轴承失效原因

某地铁受电弓拉杆球铰轴承在运行过程中发生失效断裂.采用宏观分析、断口分析、金相检验、硬度测试及化学成分分析等方法对球铰轴承的失效原因进行了分析.结果表明:该受电弓拉杆球铰轴承的断裂模式属于高周低应力疲劳断裂.球铰轴承在服役过程中承受频繁的振动和交变载荷作用,折角处的微裂纹成为疲劳裂纹源区,裂纹在交变载荷作用下不断扩展,...     

QT700-2球墨铸铁发动机曲轴失效分析

目的某厂生产的QT700-2球墨铸铁曲轴在路试过程中出现断裂,需寻找失效原因并提出解决措施。方法通过应用金相组织分析、化学成分分析、表面残余应力测试和力学性能测试等方法,对该曲轴的失效原因进行了分析。结果测试后分析结果表明,曲轴是在较大扭转循环载荷下,在第四连杆颈滚压圆角边缘多点萌生裂纹而导致疲劳断裂是其失效的主要原因。结论建议改进热处理工艺,保证组织的均匀性;改进加工工艺,减少应力集中;并强化表面残余应力以提高曲轴的疲劳寿命。     

自动扶梯主驱动链条外链板断裂分析

某自动扶梯主驱动链条外链板在运行过程中断裂失效。采用宏观检验、化学成分分析、硬度测试、非金属夹杂物检验以及金相检验等方法对外链板的断裂原因进行了分析。结果表明:外链板表面打印字头底部过渡圆角尖锐并存在折叠缺陷,同时部分原材料存在表面脱碳缺陷,导致外链板打印字头底部过渡圆角处应力集中以及材料表面抗疲劳性能降低;在多重应力的作用下外链板表面打印字头底部缺陷处萌生疲劳裂纹,裂纹不断扩展最终导致外链板疲劳断裂失效。     

某余热锅炉集箱端盖断裂脱落原因分析

对某余热锅炉省煤器集箱端盖在运行24个月后发生整体断裂脱落事故进行了分析,通过对失效端盖进行宏观分析、化学成分分析、硬度测试、金相检验、扫描电镜以及能谱分析,找出了端盖断裂失效原因。结果表明:端盖失效性质为腐蚀疲劳断裂;端盖内的运行介质中含有具有腐蚀性的氯离子,在较高温度和应力作用下促使端盖内壁产生裂纹,并在集箱内温度波动造成的热疲劳应力作用下快速扩展最终导致端盖断裂脱落。     

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