304不锈钢表面纳米化层的组织和性能

采用表面机械研磨技术(SMAT)对304不锈钢进行表面纳米化处理,利用光学显微镜、扫描电镜、X射线衍射仪、透射电镜和显微硬度仪对处理后的不锈钢表面层组织进行表征,并在不同温度下对表面纳米组织的热稳定性进行研究。结果显示,经过SMAT后,表面获得了约436μm厚度的变形层,表面晶粒尺寸约为80nm;在SMAT处理过程中发生了应变诱发马氏体相变;表层晶粒的细化能显著提高组织的显微硬度;当保温温度在550℃以下时,表层纳米组织具有良好的稳定性,当温度超过600℃时晶粒显著长大。     

调质工艺对X80级管件钢性能与组织影响研究

为研究调质工艺对X80级管件钢的性能和组织影响,通过力学性能检验、光学显微镜(OM)、透射电镜(TEM)、萃取复型及电子背散射衍射(EBSD)等手段,研究了同一温度淬火后,不同回火温度对X80级管件钢性能和组织的影响.结果表明,经940℃淬火后,在500~650℃范围内回火,试验钢的屈服强度和抗拉强度随回火温度的升高均先增加后降低.随回火温度的升高,试验钢由板条贝氏体铁素体(BF)和粒状贝氏体(GB)的混合组织转变为GB和准多边铁素体(QF)混合组织,M/A岛由细长条状变为颗粒状,并发生分解,BF中的板条亚结构逐渐弱化.在500~600℃范围内,组织中析出相随回火温度升高逐渐增多,600℃时析出相开始聚集长大,温度继续升高,析出相尺寸明显增大.回火过程中,试验钢屈服强度受基体组织软化和析出强化两方面的影响.试验钢的低温冲击韧性随回火温度升高逐渐增大,主要是大角度晶界比例增加所致.     

低合金调质钢在回火过程中的力学性能EI北大核心CSCD

研究了回火温度对低合金调质钢力学性能和显微组织的影响。结果表明:淬火态为具有自回火析出物的板条马氏体,具有良好的强韧性配合;在250℃左右回火后片状碳化物析出量增加,提高了屈服强度;在400℃回火后在板条界析出碳化物薄壳,导致回火脆性现象;高温回火后板条形态仍普遍存在,局部区域的板条合并成铁素体块晶。在550℃以上回火析出大量纳米碳化物,渗碳体明显粗化.细晶强化和析出强化是实验钢的主要强化方式。在回火过程中组织演变及析出物性质直接影响拉伸曲线特征和n值。     

焊后热处理对1.25Cr0.5Mo钢在循环水中腐蚀行为的影响

目前有关焊后热处理对1.25Cr0.5Mo钢的腐蚀行为的影响规律尚无文献报道.为此,对正火态1.25Cr0.5Mo钢分别进行淬火、高温回火及调质,模拟不同的焊后热处理,对其金相组织进行分析,并对其腐蚀行为进行电化学测试,研究了不同热处理对1.25Cr0.5Mo钢组织和耐蚀性能的影响.结果表明:正火态1.25Cr0.5Mo钢的金相组织为铁素体和珠光体,淬火组织为板条马氏体,高温回火组织为粗大铁素体和珠光体,调质态组织为均匀的回火马氏体和细小碳化物;淬火处理加速了 1.25Cr0.5Mo钢在工业循环水中的腐蚀速度;高温回火处理对腐蚀行为影响不大;调质处理显著提高了 1.25Cr0.5Mo钢的耐蚀性,是因为调质热处理细化了材料的组织,细化后的组织较晶粒粗大的淬火及淬火后高温回火组织更容易形成氧化物膜,阻碍电极的放电过程,从而获得了较好的耐蚀性能.     

深冷处理对低碳高合金马氏体轴承钢力学性能及组织的影响

利用洛氏硬度计、X射线衍射仪、扫描电子显微镜及透射电子显微镜等研究了低碳高合金马氏体轴承钢深冷处理后的硬度变化及组织演化。结果表明:深冷处理促使部分残留奥氏体转变为马氏体,导致深冷处理后实验钢的硬度较淬火态硬度有所升高。经深冷处理后实验钢在0~100 h回火过程中的硬度均比未深冷处理实验钢的硬度高。深冷处理促使钢中碳原子偏聚并在回火过程中以碳化物的形式析出,与未经深冷处理的实验钢相比,经深冷处理的实验钢回火后马氏体基体中的含碳量更低,表明实验钢经深冷处理后在回火过程中析出更多的碳化物。透射电镜分析表明,实验钢在回火过程中析出的大量弥散分布的纳米级M2C和M6C型碳化物是实验钢长时间回火后保持高硬度的主要原因。     

物理金相二级人员试题参考答案

(续上期 )1 1 .随着回火温度的升高 ,固溶在 α相中的碳化物逐渐析出 ,当温度更高时 ,亚晶粒长大并发生回复和再结晶。与此同时渗碳体发生聚集长大并球化 ,晶格恢复不再有畸变。1 2 .一般合金钢在 2 0 0～ 350°C之间出现第一类回火脆性 ,与新形成的碳化物沿马氏体条间、束的边界或在片状马氏体的孪晶带和晶界上析出有关。某些钢于 450～ 650°C之间回火时将发生脆性 ,即第二类回火脆性 ,这与杂质元素如 Sb、P、Sn、As等在晶界的偏聚有关。1 3.亚温淬火是不完全淬火 ,它是在临界区或两相区加热淬火 ,淬火后在马氏体基体上还保留少量弥散…     

一种SCWR包壳管用9-12%Cr低活性F/M钢的组织及析出相研究

运用Thermo-Calc软件进行热力学计算,预测了一种新型9-12%Cr低活性F/M(铁素体/马氏体)实验钢的组织。对淬火回火热处理后的显微组织进行了观察,并对析出物进行电子衍射结构分析和EDS化学成分检测。结果表明,实验钢是典型的回火板条马氏体组织,位于各种晶界上的析出物均为富Cr的碳化物M_(23)C_6,其化学成分随碳化物的形貌变化而变化。对实验钢进行60%冷变形并随后在820℃退火10-300 min,M_(23)C_6在完全再结晶、奥氏体相变过程中进一步球化,Cr、W不断富集,Cr/Fe逐渐升高至2后成分趋于稳定,化学组成接近于(Cr_(15)Fe_6W_2)C_6。     

一种多元低合金高碳钢的热处理组织及硬度的研究

对一种低合金高碳钢(0.81C,0.65Cr,0.89W,0.54Mo,0.23V)热处理组织及硬度研究表明,该钢退火具有多类型碳化物(M3C,M7C3,M23C6,M6C和MC),在800～840℃区间退火,处于γ相低温区原碳化物部分溶解和新碳化物重新形核生长过程,使碳化物颗粒超细化,平均尺寸0.33～0.34 μm.淬火时,因M3C、M23C6溶解于奥氏体的速度较快,在840～860℃淬火时,硬度可达HRC63～65;未溶碳化物M6C和MC(VC)有利于马氏体细化,但因其数量较少,淬火最高温度不易超过880℃.该钢在低温和中温回火有较好的抗回火性能,并能有效地促进残余奥氏体转变.该钢热处理过程组织结构特征能较好地以相平衡热力学计算结果进行解释.     

热处理工艺对18Cr23MoVRE耐磨铸钢组织及性能的影响

研究了18Cr23MoVRE耐磨钢在不同的热处理工艺下的显微组织和力学性能。研究结果表明,18Cr23MoVRE耐磨钢经不同温度淬火+300℃回火处理后,其组织均为回火马氏体基体+少量碳化物。淬火温度提高,试验钢的硬度增加,冲击韧性略有下降。在1000℃淬火+300℃回火时,试验钢获得优良的综合性能,硬度可达到HRC58.5,冲击韧性达到5.8J。     

高温长期加热对异种钢焊接接头碳迁移及组织性能的影响

本文用热处理方法对奥氏体和珠光体异种钢接头的碳迁移现象及其对接头组织和机械性能的影响进行了研究,认为:焊缝金属有析出物出现;熔合区形成一个增碳层;热影响区形成一个脱碳的铁素体带。随回火参数 P 值增加,焊缝析出物增多,晶界加厚;增碳层加宽;脱碳层铁素体晶粒长大;接头拉伸强度,弯曲角和梅氏冲击值均降低,但这种降低在一定温度(如490℃)下逐步达到饱和。     

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