7N01S-T5铝合金厚板搅拌摩擦焊接头的晶间腐蚀行为

本研究对14 mm厚的7N01s-T5铝合金搅拌摩擦焊(FSW)试样沿板厚方向进行分层切片,采用OM和TEM等微观组织表征方法及晶间腐蚀性能测试手段,研究了接头各区的晶间腐蚀行为。实验发现,焊接接头各区域的腐蚀形貌存在明显的不同。接头的热影响区腐蚀程度最严重,其中热影响区上、下表层较中心层的腐蚀更严重,这主要归因于晶界处连续分布的析出相粒子和晶粒尺寸存在差异。热机影响区位于热影响区和搅拌区的过渡位置,晶粒扭曲变形,由于受到焊接的热循环作用,晶界析出相发生了部分溶解,腐蚀倾向性相对较低。搅拌区在FSW过程中经历了剧烈的塑性变形和温升,形成细小的等轴晶,析出强化相粒子发生了完全溶解,其晶间腐蚀倾向性最低。     

5052-H112铝合金搅拌摩擦焊接头应力腐蚀的研究

采用慢应变速率拉伸法分析了6mm厚5052铝合金及其搅拌摩擦焊接头在大气及海水环境下的应力腐蚀敏感系数,通过OM、SEM、显微硬度仪等分析了接头组织形貌、断口形貌及接头硬度。结果表明:焊核区晶粒由细小的等轴晶粒组成,平均晶粒尺寸约为5μm,为母材的1/10;合金及其接头在应变速率为3.36×10-6 s-1时的应力腐蚀敏感系数分别为1%、2%,应力腐蚀系数小;硬度最小值及接头断口均位于接头返回侧热影响区,为接头的薄弱区;接头断口均由细小、均匀的韧窝组成,呈典型的切断形貌,接头在海水中的断口韧窝较大气中平而浅,这与接头的应力腐蚀倾向有关。     

厚板铝合金搅拌摩擦焊接头的冲击性能

采用搅拌摩擦焊对厚度为30 mm的2A12铝合金板材进行对焊连接,分析了接头不同厚度处的微观组织与冲击性能。结果表明:随着热输入量的减少,接头上层的晶粒相比于下层出现了粗化现象,导致接头上层区域的冲击韧性低于下层。焊核区晶粒最为细小,热机影响区次之,热影响区晶粒最为粗大;焊核区的冲击韧性高于热影响区,热机影响区由于存在微型裂纹,所以冲击韧性最低。焊核区上层的晶粒尺寸小于热机影响区下层的晶粒尺寸,但焊核区上层的冲击韧性低于热机影响区下层的冲击韧性,这是由于焊核区所含的Al₂CuMg脆性第二相的数量较多。焊接接头冲击韧性的变化不仅与焊缝不同区域的微观组织变化有关,还与该区域的第二相数量有关。     

微量Zr对Al-Zn-Mg-Mn合金板材抗剥落腐蚀性能的影响

通过腐蚀浸泡实验和电化学阻抗谱测试,研究了微量Zr的添加对Al-Zn-Mg-Mn合金板材抗剥落腐蚀性能的影响,并结合金相显微镜(OM)、电子背散射衍射技术(EBSD)、扫描透射电镜(STEM)等显微组织表征结果对影响机理进行分析和讨论。结果表明：在Al-Zn-Mg-Mn板材中添加微量Zr可以改善抗剥落腐蚀性能,剥落腐蚀等级由EB级变为EA级,最大腐蚀深度由593 μm降至421 μm。通过分析板材晶粒组织的差异和晶界η相尺寸、间距和化学成分的变化及无沉淀析出带宽度的变化,认为添加微量Zr后是通过综合作用来影响材料的剥落腐蚀行为。     

316L不锈钢焊缝腐蚀微电池的形成机理

为了探究316L不锈钢焊缝腐蚀微电池的形成机理,通过微观组织观察及电化学试验进行了分析。采用扫描电镜(SEM)对焊件三区(焊缝区、热影响区、母材区)的形貌及元素组成进行了观察分析,采用金相显微镜观察微观组织,并确定晶粒度及非金属夹杂物及其分布。结果表明:316L不锈钢焊缝形成腐蚀微电池的倾向与元素组成、非金属夹杂物和晶粒度大小等因素紧密相关;焊缝三区腐蚀电位、腐蚀电流不同,耐蚀性能差异较大,因而腐蚀电位最低的热影响区与腐蚀电位最高的母材区在电解液中比较容易形成腐蚀微电池,且热影响区可视为此微电池的阳极,腐蚀进程较快。     

用电阻法测试45钢在硫酸中的腐蚀深度

采用新型电阻法研究了棒状45钢在0.1,0.3,0.5 mol/L H2SO4液中腐蚀后的电阻与腐蚀深度的关系,建立了腐蚀深度与电阻的关系式.结果表明:用该关系式计算出的腐蚀深度精度可达0.07 μm;在测量范围内(腐蚀深度<217.25 μm),新型电阻法计算与测量出的腐蚀深度差值小于3.25 μm,平均差值为2.39 μm.试样丰径较小时,用新型电阻法计算的腐蚀深度误差更小;试样半径较大时,用传统电阻法计算的腐蚀深度误差更小.     

AZ31镁合金搅拌摩擦焊接头微弧氧化表面防护研究

在硅酸盐溶液中于AZ31镁合金搅拌摩擦焊接头表面制备一层均匀的微弧氧化膜。分析微弧氧化膜的截面组织、相组成和显微硬度分布,并采用浸泡和电化学方法评估微弧氧化表面处理对焊接接头腐蚀行为的影响。结果表明:接头搅拌区的显微硬度高于镁合金母相区,热影响区硬度低于母相区,但接头不同区域对应的微弧氧化膜硬度都相同,比镁合金基体提高约7倍。在3.5%NaCl溶液中浸泡后,焊接样品热影响区腐蚀严重,而微弧氧化膜表面形貌没有明显变化。未表面处理的接头热影响区电位低于搅拌区和母相区,其腐蚀电流密度也较大,但不同区域微弧氧化膜的腐蚀电流密度都相近,并明显低于未氧化处理的焊接样品。微弧氧化表面处理能显著改善镁合金搅拌摩擦焊接头抗腐蚀性能。     

镁合金搅拌摩擦焊接组织特征研究

通过对镁合金AZ31进行搅拌摩擦焊获得了成型良好的焊缝,采用金相显微镜对焊缝组织进行了分析,并采用透射电镜和X射线能谱仪对晶粒形貌和晶界析出的第二相进行了观测分析。结果表明,镁合金搅拌摩擦焊可以获得组织致密的焊缝,焊缝区域根据组织特点可以分为焊核区、热机影响区和热影响区;焊核区"洋葱环"之间呈现层片状结构,晶界强化相数量减少且尺寸变小;热机影响区在前进侧和焊核区有明显的分界,晶粒呈细长条状,后退侧和焊核区分界相对不明显,晶粒变形较小;热影响区在前进侧较窄,组织与母材组织相比变化较小,而后退侧热影响区较宽,晶粒尺寸有所增长,这与搅拌摩擦过程中金属切削迁移的堆积过程有关。     

腐蚀长度、宽度、深度对带大面积腐蚀缺陷管道应力的影响分析

针对大面积片状腐蚀缺陷导致管道破坏的问题,利用ABAQUS软件并结合实际数据,建立不同腐蚀条件下的腐蚀管道模型,采用正交试验法对其应力状态进行分析,将模拟结果与API579准则结果进行比较,验证其准确性.结果 表明:腐蚀长度、宽度、深度均对带大面积腐蚀缺陷管道的应力状态产生影响,其中腐蚀深度的影响最为显著,腐蚀长度的影响最小;腐蚀宽度在40°～80°范围内对管线的应力状态影响较大,当腐蚀宽度超过80°时,应力变化趋于稳定;不同腐蚀尺寸参数对管线的应力状态影响程度不同,其中腐蚀深度影响最大,所以在进行管线补强、剩余寿命预估及安全评估时,要重点考虑腐蚀深度的影响.     

中性盐雾环境中Q235钢板腐蚀率与表面特征参数的关系

为更全面地评价锈蚀钢材腐蚀发展程度,探讨钢材腐蚀后的损伤参量变化规律,通过对Q235钢板进行中性盐雾加速腐蚀,得到了钢板不同腐蚀程度下的质量损失率,并采用三维非接触式表面形貌仪测试腐蚀钢板表面,得到了钢板腐蚀后的孔洞率、平均腐蚀深度、最大腐蚀深度、表面三维粗糙度参数Sa及Sq等表面特征参数的相关数值,建立了腐蚀损伤参量的变化函数模型以及腐蚀率与表面特征参数关系式,可为材料耐蚀性研究提供基础数据。     

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.