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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. 相似文献
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珠光体耐热钢在高温时效中的材料弱化 总被引:1,自引:1,他引:0
采用了11种实验室模拟工艺(650~750 ℃、1.5~873 h),利用TEM、SEM、OM等考察了珠光体耐热钢12Cr1MoV高温长时间加热后成分、组织结构与性能的变化.研究表明,试验用钢在高温时效后其组织结构明显退化,固溶体内合金元素Cr、Mo、V严重贫化(其中Mo的降幅为2/3),发生晶粒长大(~70%),碳化物向晶界的聚集粗化,以及相变位错密度显著降低和位错胞尺寸变大及消散等,同时基体硬度下降30%.多层次结构综合分析表明,12Cr1MoV耐热钢高温时效中,由于组织结构的退化,引起其性能的劣化,导致材料的弱化(老化). 相似文献
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以电站锅炉12Cr1MoV钢高温过热器爆管为研究对象,通过宏观观察、金相检验、硬度测试、化学成分分析等方法分析了爆管背烟侧及迎烟侧管材的显微组织及力学性能差异。结果表明:该过热器管材有明显劣化现象,爆管背烟侧和迎烟侧显微组织和力学性能存在明显差异;爆管迎烟侧组织老化现象较为严重,珠光体呈4.5级球化,常温拉伸性能和硬度明显低于背烟侧的,表明炉内长期高温烟气冲刷对高温过热器管迎烟侧材质劣化影响更为明显。 相似文献
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对低碳低合金耐热钢12Cr1MoV在高温时效过程中,合金元素贫化以及从晶内向晶界扩散迁移、晶粒长大和脱溶沉淀的碳化物粒子粗化等成分、组织结构变化进行了研究,运用扩散理论、相变热力学和动力学理论对这些转变的规律进行分析和处理,并获得与实验相符合的结果.结果表明,合金元素的贫化和晶粒长大分别符合ΔC=K.t3/2和Dt=C.t1/2规律;通过Larson-Miller(P=T(C+lgt)热强参数的统一描述,指出了12Cr1MoV钢高温时效是持续而又缓慢的成分和组织结构逐渐变化(退化)的过程. 相似文献
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《理化检验(物理分册)》2017,(2)
通过热模拟试验对12Cr1MoV钢进行了不同工艺的正火+回火热处理,研究了热处理工艺对该钢显微组织及力学性能的影响。结果表明:12Cr1MoV钢正火+回火后的正常显微组织为回火贝氏体+铁素体或回火贝氏体+铁素体+珠光体或铁素体+珠光体;如果回火温度过高或正火冷却速率不足,则分别会导致钢中出现两相区组织黄块马氏体和钒的碳化物沿晶界及晶内聚集长大的情况,显著降低钢的力学性能。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
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. 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
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... 相似文献
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A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils. 相似文献
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Janet Lang 《Materials and Manufacturing Processes》2017,32(7-8):857-866
ABSTRACTThe 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. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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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. 相似文献
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The end of over unit products of more than Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits beer wine yellow wine fruit syrup wine others cover over % of the national top-branded liquor products.…… 《中国标准化(英文版)》2008,25(1):30
The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.…… 相似文献
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Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster. 相似文献
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S. K. Malhotra Paramanand Singh A. Thirunavukkarasu 《Materials and Manufacturing Processes》2006,21(7):652-657
Al2O3-ZrO2 nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness. 相似文献