Z参数法及其在耐热钢寿命预测中的应用

基于石化和发电装置常用的20钢、1Cr5Mo和12Cr1MoV三种珠光体耐热钢,提出用Z参数法来表征持久性能曲线P=Z0-Z+C1logσ+G2σ.其中Z0、C1、C2为常数,Z0确定了材料无劣化时性能曲线的位置,C1、C2确定了曲线的变化趋势;参数Z是反映了曲线偏移主曲线的位置,同时表征了相关材料持久性能的变化.进一步得到了Z参数与组织劣化程度-珠光体球化等级E之间的线性关系,并以12Cr1MoV钢为例根据其组织劣化等级定量预测了其剩余寿命.     

12Cr1MoV钢组织转变与剩余寿命预测

12Cr1MoV钢是国内电站锅炉等高温部件广泛采用的钢种.研究表明,对于在高温条件下运行的12Cr1MoV钢来说,由于组织的劣化,导致持久性能的下降,这一过程可用Larson-Miller法表示为:10-3·T·(20 lgtr)=Z-blgσ-cσ,其中b,c是常数,Z是用于表征由于组织劣化而产生的组织变化参数.通过关联数种不同组织状态的12Cr1MoV材料的持久性能数据,研究了组织、持久性能与组织变化参数之间的关系,为高温构件剩余寿命的预测提供了一种新的分析方法.     

基于应力松弛实验对服役25Cr35Ni型耐热钢的高温性能评估

以服役的25Cr35Ni型钢为对象,研究利用应力松弛实验开展高温性能评估的方法以及对持久性能的预测效果。结果表明:由于高温服役后晶界处碳化物出现网链状和奥氏体基体内二次碳化物明显粗化,25Cr35Ni型耐热钢持久性能降低。通过得到的不同温度和应力的松弛蠕变速率曲线及外推关系,结合松弛蠕变速率-断裂时间关系方程,可以实现由松弛实验及少量蠕变持久实验开展持久寿命评估。与基于高温持久实验的预测结果比较,两者吻合较好。     

12CrlMoV钢组织转变与剩余寿命预测

12Cr1MoV钢是国内电站锅炉等高温部件广泛采用的钢种。研究表明,对于在高温条件下运行的12Cr1MoV钢·T·(20+lgt来说,由于组织的劣化,导致持久性能的下降,这一过程可用Larson Miller法表示为:10-3r)=Z-blgσ-cσ,其中b,c是常数,Z是用于表征由于组织劣化而产生的组织变化参数。通过关联数种不同组织状态的12Cr1MoV材料的持久性能数据,研究了组织、持久性能与组织变化参数之间的关系,为高温构件剩余寿命的预测提供了一种新的分析方法。     

加热炉Cr5Mo炉管材料性能分析及寿命预测

以某炼油厂提供的加热炉Cr5Mo炉管为研究对象,从试验角度进行了炉管的宏观检验、化学成分分析、硬度测试、力学性能分析和金相检验。结果表明:炉管在经过长时间高温服役后屈服强度有明显降低,珠光体球化现象加重。依据高温持久性试验结果,利用等温线法和L-M参数法对炉管剩余寿命进行了预测,评估结论为在操作温度650℃及应力18MPa的条件下,该批炉管至少还能服役一个周期。     

MHZ常数在耐热钢持久性能预测中的应用

本研究提出选用MHZ常数关联耐热钢持久性能数据,以HP40和Super304钢为例比较了基于MHZ常数和标准推荐L-M常数的持久性能曲线与实验数据之间的相关性;并对工业中常用的十七种耐热钢实验数据进行分析,对比了MHZ常数和L-M常数在持久性能预测精度上的差异。结果表明不同的L-M常数对数据拟合结果有较大影响,工程应用中为保证较高预测精度需选用优化的L-M常数,否则会导致构件应用时偏危险;对所分析的大部分钢新选用的MHZ常数不仅具有更高预测精度和更优拟合效果,而且能更直观比较不同耐热钢之间的持久性能,故可以作为耐热钢的TTP参数。     

长期服役Cr9Mo炉管的持久性能及剩余寿命预测

针对长期服役后的Cr9Mo炉管材料的金相组织及力学性能等进行了研究,并在此基础上,确定了炉管材料的劣化程度及其剩余寿命.这些研究对Cr9Mo炉管的高温性能、寿命预测及延寿策略的制定具有指导意义.     

2.25Cr-1Mo的焊接及回火脆化倾向评定

珠光体耐热钢是以Cr-Mo为主的合金钢,合金元素的质量分数一般小于10%,钢的显微组织为珠光体+铁素体或贝氏体+铁素体。珠光体耐热钢有较好的抗氧化性和高温蠕变强度,广泛用于石油化工行业中高压、高温、临氢设备的制造。珠光体耐热钢的焊接一直是压力容器生产制造过程中的重点难点。该文以2.25Cr-1Mo(12Cr2Mo1R)为例介绍一下珠光体耐热钢的焊接工艺,并对焊接接头进行回火脆化倾向评定。     

碳迁移对镍基和奥氏体焊条焊接的Cr5Mo异种钢焊接接头蠕变破断寿命的影响

基于节约费用和施工方便的考虑，工程应用中常采用异种钢焊接。Cr5Mo异种钢焊接接头广泛应用于炼油、石油化工等过程工业中的高温环境。针对镍基和奥氏体焊条焊接的Cr5Mo异种钢焊接接头，通过时效处理和蠕变持久实验，研究了碳迁移对蠕变破断强度与时间的影响。研究表明，奥氏体焊条焊接的Cr5Mo异种钢焊接接头由于碳迁移蠕变破断强度下降，破断寿命减少，约为镍基焊条焊接的Cr5Mo异种钢焊接接头蠕变破断寿命的50％。     

X20CrMoV12.1钢的组织结构和缺口疲劳强度

用扫描电镜和透射电镜观察X20CrMoV12.1耐热钢在545℃长期运行后的微观组织结构变化,研究了不同运行时间后材料的缺口疲劳强度和硬度.结果表明:经过高温长期运行后,X20CrMoV12.1钢的组织明显退化,其显微组织由原来的马氏体板条结构和弥散分布的细小碳化物逐步转变为亚晶粒和分布在晶界上的粗化球形碳化物组织;随着在高温下运行时间的增加,耐热钢的显微硬度和疲劳强度逐渐降低.其原因是基体中固溶体主要合金元素Cr,Mo,V发生贫化,固溶强化效果降低,沿晶界分布的粗化球形碳化物弱化了材料晶界强度,从而导致X20CrMoV12.1耐热钢高温服役寿命下降.     

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.……     

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.     

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.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to