弹簧钢带冷冲压起皮原因分析

某公司对进口的冷轧弹簧钢带(50CrVA)进行冷冲压加工时，钢带表面沿轧制方向出现了起皮、剥离等现象。对该钢带进行化学成分、力学性能和金相组织等检验。结果表明，钢带的原材料中已存在冶金缺陷以及各类夹杂物，同时还有严重的带状偏析组织，这些都是钢带表面存在微裂纹的原因。当该钢带在冷加工时，促使裂纹沿轧制方向扩展，最终导致钢带起皮和剥离。     

45A圆钢矫直断裂原因分析

通过对45A圆钢进行化学成分、金相组织、夹杂物、低倍检验,发现夹杂物较严重,且圆钢截面低倍组织存在严重裂纹.夹杂物和截面裂纹的共同作用,使圆钢发生了矫直断裂.     

Q460C中厚钢板折弯裂纹形成原因

某厂生产厚度为20 mm的Q460C钢板在折弯过程中出现裂纹。采用宏观观察、化学成分分析、金相检验、扫描电镜及能谱分析等方法分析裂纹产生的原因。结果表明：试样折弯裂纹产生的主要原因为炼钢过程中钢液中P、S元素含量过高,且连铸过程存在钢包下渣的情况,导致铸坯中产生P、S元素偏析,铸坯内部存在大量非金属夹杂物;随着轧制过程温度的不断降低,钢板内部形成严重的带状组织,最终导致钢板在折弯过程中发生开裂。     

Q345B宽带钢边缘裂纹分析

采用化学成分分析、力学性能测试、显微组织观察和夹杂物检验等方法对有边缘裂纹的Q345B宽带钢进行分析。发现是由于铸坯存在FeS,MnS等夹杂物,轧制中这些夹杂物及过高锰含量导致裂纹的进一步扩展,最终形成边缘裂纹。     

Q550D钢拉伸试样断口分层原因

某Q550D钢拉伸试样在拉伸试验后出现拉伸断口分层现象。通过宏观观察、金相检验、硬度测试、能谱分析等方法,对拉伸断口的分层原因进行了分析。结果表明:Q550D钢板坯在连铸过程中采用了不适宜的连铸工艺,造成连铸钢坯在上、下1/4处出现成分正偏析,在连铸钢坯的1/2处存在负偏析、夹杂物,后续经轧制后在板材的1/4厚度处存在较严重的贝氏体偏析带,在心部区域有大量的B类夹杂物,最终导致拉伸试样断口出现分层现象。     

某宽厚钢板等离子切割开裂原因

在某宽厚板的等离子切割工序中,其板厚1/2处产生中心裂纹。采用宏观观察、化学成分分析、金相检验、扫描电镜及能谱分析、硬度测试等方法分析该钢板开裂的原因。结果表明：在钢板1/2厚度处存在明显的偏析带,基体和偏析带的显微组织分别为回火马氏体和淬火马氏体,在偏析带中分布有长条状夹杂物,裂纹从夹杂物处萌生并扩展;等离子切割后的淬硬层硬度较大,具有很大的淬硬倾向,在热应力和组织应力的作用下,钢板最终开裂。     

中厚板轧材探伤不合的原理分析与措施

因铸坯内部质量原因造成轧材探伤不合的原因主要有四个,分别是氢致裂纹,铸坯内部的中心偏析与裂纹,铸坯内部的夹杂物和铸坯内部的带状组织发达。本文针对中厚板生产中出现的轧材分层问题展开分析,从连铸坯的内部质量缺陷和轧钢的压下量等方面分析轧材分层产生的原因及预防措施。     

Q235中板冷弯开裂原因探讨

Q235钢板在冷弯时出现开裂，采用扫描电子显微镜对开裂件进行了观察。结果表明，钢板表皮下存在的大量夹杂物，在轧制过程中极易形成裂纹源，并由此产生裂纹的延伸扩展，最终导致钢板冷弯时开裂。消除钢板冷弯开裂的主要措施是提高钢水的纯净度以减少其内部夹杂物。     

中厚板材表面纵裂纹成因分析

用光学显微镜和电子显微镜对中厚板轧后出现的表面纵裂纹进行了观察和分析。发现钢板横截面上的裂纹都有向内扩展的趋势．在裂纹面和裂纹周围都存在夹杂物，且夹杂物成分中有结晶器保护渣的特有成分钠和钾；裂纹面上有大量气泡，沿轧制方向呈簇状分布。因此认为，凡影响初生坯壳凝固均匀性的因素对纵裂纹的产生都有影响，其中保护渣的性能和皮下气泡是钢材产生表面裂纹的主要原因。     

余热处理钢筋剪切开裂分析

通过金相检验、扫描电镜观察、夹杂物分析和工艺分析等手段对牌号为HRB335,规格为击Ф22mm的余热处理钢筋剪切开裂的原因进行了分析。结果表明：是由于连铸坯内部裂纹中存在的夹杂物导致铸造裂纹在轧制过程中不能被焊合,从而引起了钢筋剪切开裂。     

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.     

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.     

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 ...     

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     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.