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71.
Stacking fault energy and stacking fault nucleation energy are defined in terms of the physical nature of stacking faults and stacking fault energy, and the measuring basis for stacking fault energy. Large quantities of experimental results are processed with the aid of a computer and an expression for calculating stacking fault energy has been obtained as γ300SF(mJ·m-2)=γ0SF+1.59Ni-1.34Mn+0.06Mn2-1.75Cr+0.01Cr2+15.21Mo-5.59Si-60.69(C+1.2N)1/2 + 26.27(C+1.2N)(Cr+Mn+Mo)1/2+0.61[Ni·(Cr+Mn)]1/2. 相似文献
72.
Mahdi Alipour Mohammad Amin Torabi Mohammad Sareban Hadi Lashini Ehsan Sadeghi Abolfazl Fazaeli 《基于设计的结构力学与机械力学》2020,48(5):525-541
AbstractIn this article, we investigated the effect of martensite morphology on the mechanical properties and formability of dual phase steels. At first, three heat treatment cycles were subjected to a low-carbon steel to produce ferrite–martensite microstructure with martensite morphology of blocky-shaped, continuous, and fibrous. Tensile tests were then carried out so as to study mechanical properties, particularly the strength and strain hardening behavior of dual phase steels. In order to study the formability of dual phase samples, Forming Limit Diagram was obtained experimentally and numerically. Experimental forming limit diagram was obtained using Nakazima forming test, while Finite Element Method was utilized to numerically predict the forming limit diagram. The results indicated that the dual phase samples with fibrous martensite morphology had the highest tensile properties and strain rate hardening out of the three different microstructures. Blocky-shaped martensite morphology, on the other hand, had the worst mechanical properties. The study of the strain hardening behavior of dual phase sample by Kocks–Mecking-type plots, evinced two stages of strain hardening for all specimens with different microstructures: stages III and IV. The forming limit diagram of dual phase steels also proved that samples with fibrous martensite morphology had the best formability compared to other two microstructures. The simulated forming limit diagram manifested that there is a good agreement between experimental results and those obtained by FEM. 相似文献
73.
为了提高对城市燃气管道泄漏检测的准确性,该文提出了一种基于声波与压力波耦合的识别方法,并通过实验考察了它的可行性。实验发现管道的气体泄漏引起了两个显著特征,即泄漏噪声与压力下降。泄漏噪声的强度随泄漏量增大而增大,但噪声的频率基本保持不变;管道内压力降低的速率与泄漏量大小正相关。据此发展了一种基于相关算法的泄漏耦合识别方法,通过判别泄漏噪声与压力降是否同时出现,以及相关函数值大小与阈值对比,来判别泄漏是否发生及其大小。实验验证了耦合识别方法的有效性,并展示了比单一信号识别方法更好的抗干扰能力。 相似文献
74.
Computer models can provide the basis for real‐time monitoring and control of fluid flow in pipelines. Problems of fluid flow in pipelines are mathematically represented by a non‐linear system of coupled partial differential equations. In this paper, several numerical techniques are evaluated with respect to their suitability for the purpose of real‐time monitoring of fluid flow in pipelines. The proposed techniques are evaluated in terms of the L1, the L2, and the L∞ error norms. Moreover, the developed simulators will be compared in terms of their speed of response and settling time which are essential factors for an effective real‐time monitoring scheme. Finally, the selected simulation scheme is further tested under assumed pipeline leak conditions. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
75.
L. M. Ocampo C. O. R. Mattos I. C. P. Margarit-Mattos J. D. Fabris M. C. Pereira H. R. Rechenberg D. L. A. de Faria 《Hyperfine Interactions》2006,167(1-3):739-746
Four samples of steels with alloying elements were exposed to an industrial environment during 1,955 days, aiming to elucidate the effect of the alloying elements Cu and Ni on the resistance of weathering steels to corrosion processes. The samples were characterized with optical microscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), saturation magnetization measurements and with energy dispersive (EDS), infrared, Mössbauer and Raman spectroscopies. All the steels originated orange and dark corrosion layers; their thicknesses were determined from the SEM images. EDS data of such rust layers showed that the alloying element content decreases from the steel core towards the outer part of the rust layer. Moreover, in the dark rust layer some light-gray regions were identified in the W and Cu-alloy steel, where relatively higher Cr and Cu contents were found. XRD patterns, infrared, Raman and Mössbauer spectra (298, 110 and 4 K) indicated that the corrosion products are qualitatively the same, containing lepidocrocite (γFeOOH; hereinafter, it may be referred to as simply L), goethite (αFeOOH; G), feroxyhite (δ′FeOOH; F), hematite (αFe2O3; H) and magnetite (Fe3O4; M) in all samples; this composition does not depend upon the steel type, but their relative concentrations is related to the alloying element. Mössbauer data reveal the presence of (super)paramagnetic iron oxides in the corrosion products. Saturation magnetization measurements suggest that feroxyhite may be an occurring ferrimagnetic phase in the rust layer. 相似文献
76.
4-(2-Thiazolylazo)resorcinol (TAR) is used as a chelating reagent in the reversed-phase HPLC separation and determination of transition and rare earth elements in low-alloy steels. A precolumn derivatization method is used, followed by separation on an octadecyl-bonded silica stationary phase with a sodium octane-1-sulphonate-tartaric acid mobile phase. The eluted metal chelates are detected by uv-visible spectrophotometry. The requirements for sample preparation, characterization of precolumn derivatization and the optimum conditions for the sensitive detection of metal ions after liquid chromatography (LC) separation are discussed. The influence of the pH of the chelating medium and the eluent, the concentration of TAR and the eluent were investigated. The results are compared with those of other methods such as atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). 相似文献
77.
肯基亚克盐下油田8033井地面管线堵塞机理的研究 总被引:3,自引:0,他引:3
通过堵塞物的分离和组分分析,探讨了哈萨克斯坦肯基亚克盐下油田8033井地面管线的堵塞机理。利用有机溶剂对其堵塞物进行了分离,各组分的含量如下:无机杂质2.78%,正庚烷沥青质0.12%,胶质4.76%,蜡33.25%。利用X射线衍射分析技术分析了无机物杂质的组成,其中的石英成分高达85.9%。利用高温气相色谱技术分析了蜡样的碳数构成,其中C40以上的蜡成分约占50%。通过堵塞物样品粘温曲线的测定,研究了堵塞物样品的流变特性,并确定了其析蜡点温度为65℃。实验结果表明,盐下油藏8033井地面管线的堵塞原因主要是由于在地面温度下原油中高碳蜡的析出,并与无机杂质协同作用,加剧了堵塞物的形成。据此提出了现场解除堵塞物的措施以及今后生产过程中需要采取的预防措施。 相似文献
78.
We describe the quantitative determination of low nitrogen contents (< 1 %wt) in highly-alloyed, duplex stainless steels
by EPMA using a calibration curve. Five monophasic stainless steels with various nitrogen concentrations were used for the
calibration curve, namely, three highly alloyed steels prepared in the laboratory, with nitrogen contents 0.066, 0.565 and
1.016 %wt and two industrial alloys with nitrogen concentrations 0.174 %wt and 0.023 %wt. For these samples, the plot of nitrogen
X-ray intensities versus nitrogen contents exhibited an acceptable linear relationship. Average nitrogen contents of the analysed
duplex alloys were found to vary in the range < 0.045–0.07 %wt in ferrite and 0.52–0.77 %wt in austenite. These results suggest
that the nitrogen solubility limit in ferrite has been reached; on the other hand, nitrogen solubility in austenite increases
due to the high manganese and low nickel contents. 相似文献
79.
Mary Kamburova 《Mikrochimica acta》1998,128(3-4):177-180
The interaction of Cr(VI) and Nitrotetrazolium Blue has been examined. A 12 NTB (CrO3Cl)2 ion-associate is formed and is extractable into 1,2-dichloroethane. The optimum conditions have been established. The molar absorptivity at 260 nm was (8.2 ± 0.06) × 104L mol–1cm–1. Beer's law was obeyed in the range 0.01–0.4 g ml–1 Cr(VI). A sensitive and selective method for determination of micro-quantities of Cr(VI) in soils and steels is suggested. 相似文献
80.
Needham D. J.; Billingham J.; Schulkes R. M. S. M.; King A. C. 《IMA Journal of Applied Mathematics》2008,73(1):274-322
In this paper, we develop a hydraulic theory to describe theoccurrence and structure of slugging in a confined two-layergas–liquid flow generated by prescribed, constant, upstreamvolumetric flow rates in each layer. A linearized theory forthe uniform flow is established, after which we use bifurcationtheory to study fully non-linear periodic travelling wave structures.We find that a two-parameter family of such travelling wavesolutions exists. Under given conditions, the volumetric flowrate constraint provides a relation between these two parameters.To select a unique periodic travelling wave solution, we requirea further relation. We first investigate the conjecture thatthe periodic travelling wave solution selected in the initialvalue problem has the same wavelength as the linearly most temporallyunstable mode. To do this, we solve the initial value problemnumerically on a periodic domain. We find that the separationof the liquid slugs that form is much longer than the wavelengthof the most unstable temporal mode. We then develop a differentconjecture based on the convective instability of the long tailsof the available periodic travelling wave solutions, which leadsto a better understanding of the wavelength selection process. 相似文献