堆焊层数对热丝脉冲TIG堆焊Inconel625的腐蚀性能研究

为了研究热丝脉冲TIG(惰性气体钨极保护焊)堆焊不同层数Inconel 625后堆焊层的腐蚀性能差异,在20钢基体表面分别堆焊单层和双层Inconel 625,通过电化学试验、晶间腐蚀试验和EDS成分分析,对不同层数堆焊层的腐蚀性能进行了对比分析。结果表明：其bode谱中双层堆焊的相位角为80°,单层堆焊和基材的相位角分别下降5°和20°,双层堆焊的阻抗模量与频率的斜率最大,其次是单层堆焊的,基材的最小;基材的容抗弧最小且存在Warbug扩散,双层堆焊的容抗弧最大,单层和双层堆焊较基材的自腐蚀电位分别提高了374.0 mV和392.0 mV,腐蚀电流密度分别下降约99.3%和99.8%,双层堆焊的点蚀电位较单层的提高了430 mV。晶间腐蚀试验后,堆焊层均未出现明显晶间腐蚀而表现为点蚀,双层堆焊的腐蚀失重约为单层的1/5,腐蚀沿柱状晶间贯穿。堆焊层间融合区以及与基体交界处的合金元素变化显著,层内分布均匀,双层堆焊的Fe元素含量低于单层堆焊的,具有更好的耐腐蚀性能。     

汽轮机转轴表面CMT修复层微观组织及力学性能对比研究

目的 针对汽轮机Cr12Ni WMo V转轴在高温环境下的磨损失效问题,对失效部位进行堆焊修复。方法 选用Inconel 625合金和316L不锈钢2种材料,利用冷金属过渡（CMT）技术在汽轮机转轴表面进行堆焊修复再制造。利用光学显微镜、扫描电子显微镜、维氏硬度计和万能试验机等手段,对2种堆焊修复材料和母材的结合情况进行测试和分析,探究其微观组织和力学性能的差异。结果 光学显微镜结果表明,Inconel 625合金和316L不锈钢的熔覆层与基体具有良好的冶金结合,修复试样无缺陷。316L不锈钢修复层组织为奥氏体+δ-铁素体,而δ-铁素体的形成会导致修复层硬度降低、塑性下降;Inconel 625合金修复层的微观组织以奥氏体为基体,具有典型的柱状晶结构,且在枝晶间区域观察到Nb、Mo元素的大量偏聚,这会导致不规则形状的Laves相和细小的MC碳化物在枝晶间区域大量析出。Laves相为脆性相,在室温拉伸过程中易成为裂纹的主要形核点,造成裂纹的产生与扩展,使修复层的延伸率降低。结论 与316L不锈钢相比,Inconel 625合金修复层具有更高的强度和硬度,更适合成为汽轮机转轴表面的堆焊修复...     

基体表面粗糙度对热丝TIG堆焊Inconel625组织和耐腐蚀性能的影响

基体表面粗糙度对堆焊层组织和性能有着深刻的影响。采用热丝TIG在AISI8630表面堆焊Inconel625,研究基体表面粗糙度对堆焊层组织和耐腐蚀性能的影响。应用OM,EDS及SEM等对堆焊层的元素分布以及显微组织进行分析,采用失重法测定堆焊层腐蚀速率。结果表明:随着基体粗糙度值的减小,堆焊过程的陷光效应相应减弱,堆焊稀释率降低。堆焊层中铁元素含量随之减少,显微组织更加细化,分布更加均匀。当基体粗糙度值由12.5μm减小到0.4μm时,堆焊层耐腐蚀性能提高32%。     

水导轴承等离子堆焊Ni60合金组织及其耐腐蚀性能

采用等离子堆焊技术在Z2CN18-10核电用不锈钢表面堆焊Ni60合金,并研究Ni60合金堆焊层的组织结构、硬度和耐蚀性能。结果表明:堆焊层组织主要由γ-Ni、碳化物、硼化物以及γ-Ni和硼化物的共晶组成,堆焊层的底层、中间层和顶层位置各相体积分数不同,中间层菊花状组织最多。Ni60堆焊层硬度约为500HV,明显高于Z2CN18-10不锈钢基体,菊花状共晶组织有助于提高堆焊层硬度。Ni60在硼酸中的钝化能力明显高于海水,且与Z2CN18-10不锈钢的自腐蚀电位差较小,不易发生电偶腐蚀。在模拟海水中堆焊层中间层耐腐蚀性能优于堆焊层的底部和顶部,与基体的自腐蚀电位差较大,容易出现电偶腐蚀。     

两种合金在氯化物熔盐中腐蚀行为研究

氯化物熔盐是太阳能热发电储热系统具有前景的储热介质,但其对金属材料具有很强的腐蚀性。研究了太阳能热发电系统两种常用材料316L不锈钢和Inconel 625合金在900℃的NaCl、KCl、MgCl2和CaCl2熔盐中的腐蚀行为,采用XRD、带有能谱分析系统的扫描电镜分析了腐蚀产物的相组成和形貌。研究结果表明:两种材料在氯化物熔盐中均腐蚀严重,但在碱土金属氯化物熔盐(MgCl2、CaCl2)中的腐蚀程度要比它们在碱金属氯化物熔盐(NaCl、KCl)中严重得多。与Inconel 625合金相比,316L不锈钢在同种氯化物熔盐中的腐蚀速度较快。造成这种现象的原因是316L不锈钢表面的腐蚀产物FeCr2O4和Fe3O4比Inconel 625合金表面的腐蚀产物更易在氯化物熔盐中溶解。研究结果将有助于太阳能热发电系统的选材和发展腐蚀防护技术。     

NiCrBSi堆焊层的电化学腐蚀失效过程

在碳钢表面制备NiCrBSi耐蚀合金堆焊层,采用腐蚀浸泡试验和交流阻抗法研究了镍基合金层在3.5%NaCl溶液中的腐蚀失效过程.镍基堆焊层具有良好的耐蚀性能,交流阻抗测试过程中利用恒电位极化进行加速腐蚀.结果发现,夹杂物的存在是堆焊层发生局部腐蚀的根本原因,减少夹杂物的数目和减小夹杂物的体积可以有效提高堆焊层的耐蚀性能.堆焊层耐蚀性能稳定,阻抗随腐蚀的进行略有下降,腐蚀体系的等效电路为典型的Randles等效电路.如果堆焊层某些局部区域腐蚀严重,表面有基底露出点,则堆焊层阻抗显著减小,体系的等效电路发生变化,堆焊层与基底间即使没有发生宏观的电偶腐蚀也会失效.自然腐蚀电位测试结果证明,可以通过监测结构件电极电位的变化来判断堆焊层的腐蚀失效情况.     

稀土La2O3对CMT堆焊Inconel 625合金显微组织和抗高温氧化性能影响

目的 研究稀土氧化物对CMT堆焊镍基合金显微组织和性能的影响规律。方法 采用静电自组装工艺制备含有1%(质量分数,下同)La2O3的Inconel 625药芯焊丝,再采用CMT堆焊工艺制备Inconel 625和1% La2O3/Inconel 625镍基合金试样。系统研究添加La2O3对Inconel 625堆焊试样显微组织、显微硬度、拉伸强度及抗高温氧化性能的影响。结果 添加了La2O3的Inconel 625堆焊试样的金相组织明显细化,且显微组织由柱状晶转变为等轴晶。基体组织主要为γ–Ni固溶体和少量Laves相,且添加了La2O3的镍基合金Laves相的尺寸更为粗大。随着稀土氧化物La2O3的添加,显微硬度值从(235.97±2.99)HV0.3增加到(246.53±4.10)HV0.3,抗拉强度从543.12 MPa增加到564.25 MPa。在高温氧化试验条件下,CMT堆焊1% La2O3/Inconel 625试样的氧化速率明显小于未添加La2O3的Inconel 625原始试样的氧化速率。结论 稀土La2O3的添加产生了细晶强化以及柱状晶向等轴晶的转变,使Inconel 625堆焊试样的显微硬度和抗拉强度都有了一定的提升。在高温氧化过程中,稀土La2O3可作为Cr2O3氧化物的形核中心,促进致密Cr2O3氧化膜生长,相应提升了其表面的抗高温氧化性能。     

3.5% NaCl溶液中Inconel 690合金微动腐蚀与磨损的交互作用特性

使用PLINT微动腐蚀试验机,位移幅值(D)为100~250μm,法向载荷(Fn)为20~80N,频率(f)为2 Hz,循环次数(N)为10 000次,在3.5%的NaCl溶液中进行了Inconel 690合金微动腐蚀试验。结果表明:微动腐蚀与磨损成正交互作用,腐蚀对磨损的促进量是交互作用量增加的主要部分;微动引起腐蚀电位负移,载荷和位移幅值增加均引起腐蚀电流及腐蚀速率增加;磨痕表面可观察到磨损与腐蚀共同作用及相互促进的形貌特征。Inconel 690合金在3.5%的NaCl溶液中的微动腐蚀机理主要是磨损腐蚀、剥层和磨粒磨损的递进及协同作用。     

镍基625合金电子束熔覆TiC涂层表面改性研究

目的 采用电子束表面改性技术对Inconel 625镍基合金进行电子束表面合金化(EBSA)处理,制备性能良好的TiC涂层,提高Inconel 625镍基合金的表面性能。方法 采用不同的电子束扫描速度(80、100、120 mm/min)在Inconel 625镍基合金表面制备TiC涂层,使用扫描电镜(SEM)拍摄合金区横截面进行EDS能谱分析,使用电子背散射衍射仪(EBSD)对合金层进行EBSD表征分析,使用显微硬度仪测量EBSA后的表面硬度,使用摩擦磨损试验机(RTEC)测试表面耐磨性、生成摩擦曲线并拍摄磨损表面的三维形貌。结果 从宏观形貌上来看,在80 mm/min扫描速度下涂层成形质量最好。微观组织测试结果表明,随着扫描速度的增大,平均晶粒尺寸增大。显微硬度测试结果表明,随着扫描速度的增大,表面硬度呈现降低的趋势,但涂层表面硬度均高于基材硬度。当扫描速度为80 mm/min时,TiC强化颗粒较多分布在表面,其表面硬度最高,为457HB,与基材相比,表面硬度提高了1.936倍。耐磨性测试结果表明,当扫描速度为80 mm/min时,磨损体积和磨损率最低,分别为0.913 1 mm<...     

Inconel 625合金中析出相演变研究进展EI北大核心CSCD

本文综述了Inconel 625合金析出相的析出与演变行为,重点介绍了该合金不同类型析出相包括γ′相、γ″相、δ相、Ni2(Cr,Mo)相以及MC,M6C,M23C6型碳化物和Laves相;阐明不同成形工艺、热处理及高温蠕变过程中析出相的析出与演化行为,论述不同类型的析出相对合金性能的影响;指出Inconel 625合金快速成形及焊接过程中产生裂纹的主要因素,并提出未来重要的发展方向是如何通过选择与控制相析出来进一步提高Inconel 625合金的热强性和热疲劳性能。     

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