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1.
将17-4PH不锈钢锻棒固溶处理后油冷,然后选择在最佳的时效温度480 ℃时效保温0~5 h后空冷。通过光学显微镜(OM)、超景深显微镜、XRD、显微硬度仪等测试方法观察固溶、时效过程的组织演变和分析其沉淀硬化机理;采用电阻仪间接测试ε-Cu相动态时效析出过程对电阻的影响;并利用摩擦磨损试验机测试其耐磨性能。研究发现:17-4PH不锈钢固溶和时效过程没有残留奥氏体和逆转变奥氏体出现,热处理后出现板条状和块状两种马氏体形态,板条状马氏体硬度高于块状马氏体,随着时效时间的延长,两种马氏体硬度同步上升,时效析出明显提高了固溶态组织的硬度;时效2.0~2.5 h附近强化效果和耐磨性能最弱,可能与ε-Cu 相长大及与位错交互作用有关;硬度随时效时间的变化趋势与电阻正好相反。 相似文献
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An extension of ASM2d including pH calculation 总被引:2,自引:0,他引:2
This paper presents an extension of the Activated Sludge Model No. 2d (ASM2d) including a chemical model able to calculate the pH value in biological processes. The developed chemical model incorporates the complete set of chemical species affecting the pH value to ASM2d describing non-equilibrium biochemical processes. It considers the system formed by one aqueous phase, in which biochemical processes take place, and one gaseous phase, and is based on the assumptions of instantaneous chemical equilibrium under liquid phase and kinetically governed mass transport between the liquid and gas phase. The ASM2d enlargement comprises the addition of every component affecting the pH value and an ion-balance for the calculation of the pH value and the dissociation species. The significant pH variations observed in a sequencing batch reactor operated for enhanced biological phosphorus removal were used to verify the capability of the extended model for predicting the dynamics of pH jointly with concentrations of acetic acid and phosphate. A pH inhibition function for polyphosphate accumulating bacteria has also been included in the model to simulate the behaviour observed. Experimental data obtained in four different experiments (with different sludge retention time and influent phosphorus concentrations) were accurately reproduced. 相似文献
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研究了17-4PH钢连续加热条件下的相变行为。结果表明,17-4PH钢在连续加热条件下,相变临界点Ac1、Ac3都随加热速率的加大而提高,转变温区也相应向高温扩展。奥氏体转变量与温度的关系呈S形,转变速率df/dt非定值且存在一个峰值。通过Kissinger法计算,确定17-4PH不锈钢的奥氏体化相变激活能为47.3kJ/mol。 相似文献
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摘要:研究了不同含量的稀土Y对选区激光熔化技术(SLM)用PH13 8Mo钢粉末特性的影响,并通过Thermo-Calc热力学软件、粉体综合特性测试仪、霍尔流速计、激光粒度分析仪、扫描电镜和电子探针等方法对不同Y含量的PH13-8Mo钢粉末特性的变化规律进行研究。结果表明,随着金属粉末中Y含量的增加,金属粉末的松装密度从3.73提高到3.93g/cm3,50g粉末的自由流动时间从25.44减小到25.11s,粉末的流动性变好。同时,PH13 8Mo钢粉末的平均粒径从37.29减小到30.99μm,粉末的粒度分布区间变窄。研究还发现,不含Y的PH13-8Mo钢粉末的组织由树枝晶和等轴晶组成,而Y质量分数为0.080%的PH13 8Mo钢粉末的组织均由等轴晶组成。综上,在PH13.8Mo钢粉末中加入稀土Y,粉末的特性得到优化。 相似文献
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15-5PH steel is one of the martensitic precipitation-hardened stainless steels, which is extensively applied in the aero shafts, and electron beam welding is a significant procedure to manufacture the parts. To verify the dimension accuracies and properties, EBW with oscillation was employed on the cylinders of 15-5PH steel. The welding distortions were measured, and the microstructures and tensile properties of the joints were investigated. The weld appearances of the cylinders were smooth, and the morphology was parallel. After EBW, the shrinkages of the cylinders were above ?0.22?mm, and the welding distortions were ?0.66 to ?1.1‰, and the straightnesses were less than 1‰ due to the distortions. The martensites and a few austenites were in the welds of the cylinders after heat treatment, and the microhardnesses in the welds were 445 HV0.2, which were bigger and more homogeneous than those of the as-welded. The tensile strength and yield strength of the joints were respectively 1300 and 1150?MPa, which were higher than those of the as-welded joints, and the elongation rate of the joints was 10%. The microstructures and properties of the cylinders conformed to the aero shafts, which was attributed to the microstructure transformation with oscillation EBW and heat treatment. 相似文献
10.
余锡华 《安徽水利水电职业技术学院学报》2012,12(2):7-9
文章介绍了生态绿色混凝土在水利工程中应用并对原材料的选择,配合比的确定,混凝土搅拌、运输、浇筑的施工控制进行了探讨。 相似文献