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排序方式: 共有639条查询结果,搜索用时 15 毫秒
41.
通过等效应变、轧制压下量和轧制温升的理论分析以及纯铜的变形试验,研究室温累积叠轧变形(accumulative roll bonding,ARB)制备超细晶铜板。结果表明,室温ARB变形可以获得超细晶板带材,纯铜6道次ARB变形后.平均晶粒大小约为0.5μm。 相似文献
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The microstructure and mechanical properties of a precipitation hardenable Al–Mg–Si alloy subjected to cryorolling (CR), short annealing and ageing treatments are reported in this present work. The pre-cryorolled solid solution treatment combined with post-CR short annealing (155 °C for 5 min) and then ageing treatment (125 °C for 12 h) has been found to be the optimum processing condition to obtain the ultrafine grained microstructure with substantial improvement of tensile strength (286 MPa) and good tensile ductility (14%) in the Al–Mg–Si alloy. The significant improvement of the mechanical properties of the cryorolled and peak aged 6063 Al alloys have been observed as compared to its bulk alloys in the peak-aged condition (T6). 相似文献
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不同应力路径下粗粒料的颗粒破碎试验研究 总被引:16,自引:1,他引:15
采用大型三轴试验机,对粗粒料进行了常规三轴、等p和等应力比等不同应力路径的试验,研究了粗粒料在不同应力路径下的颗粒破碎情况,分析了应力路径对颗粒破碎和强度特性的影响,并对颗粒破碎与塑性功之间的关系进行了探讨。试验结果表明,应力路径对粗粒料的强度特性影响并不显著;颗粒破碎主要与加载过程中输入的塑性功有关,颗粒相对破碎率随着输入塑性功的增大而增大,与塑性功呈较好的双曲线关系;颗粒破碎的增加将导致峰值内摩擦角的减小,峰值内摩擦角与颗粒相对破碎率之间呈线性关系。 相似文献
46.
Microstructures and Toughness of Weld Metal of Ultrafine Grained Ferritic Steel by Laser Welding 总被引:2,自引:0,他引:2
3 mm thick 400 MPa grade ultrafine grained ferritic steel plates were bead-on-plate welded by CO2 laser with heat input of 120~480 J/mm. The microstructures of the weld metal mainly consist of bainite, which form is lower bainite plates or polygonal ferrite containing quantities of dispersed cementite particles, mixed with a few of low carbon martensite laths or ferrite, depending on the heat input. The hardness and the tensile strength of the weld metal are higher than those of the base metal, and monotonously increase as the heat input decreases. No softened zone exists inheat affected zone (HAZ). Compared with the base metal, although the grains of laser weld are much larger, the toughness of the weld metal is higher within a large range of heat input. Furthermore, as the heat input increases, the toughness of the weld metal rises to a maximum value, at which point the percentage of lower bainite is the highest, and then drops. 相似文献
47.
黄丽琴 《上海电机学院学报》2005,8(3):76-78
从钢铁材料学科的理论和技术发展角度出发,结合市场发展的需求,论述了微合金化钢、超细晶粒钢、氮合金化不锈钢、钢材组织性能预报和材料信息化技术等先进钢铁材料的技术进展。 相似文献
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Ultrasonic energy is widely used in wire bonding for microelectronics packaging. It is necessary to ensure that the maximum ultrasonic vibration displacement occurs at or near the tip of the bonding tool (capillary) for optimal performance. In this study, amplitude profiles of ultrasonic vibrations along capillaries were measured with load using a laser interferometer. This provided valuable information in understanding and improving capillary performance. The method was applied to real time applications to optimize capillary designs and bonding processes for specific bonding applications. First, the application of a new capillary material with different zirconia compositions was evaluated. The new material with certain amount of zirconia composition showed that it was the capillary material of choice for ultra-fine pitch wire bonding. Next, comparative analysis was conducted to investigate the ultrasonic energy transfer of a new ‘slimline’ bottleneck and the conventional bottleneck. The actual bonding response of the molded slimline bottleneck showed comparable performance with the ground conventional bottleneck using the same bonding parameters. Finally, optimization of a 60-μm-bond-pad-pitch process was performed on a wire bonder. Within the optimized parameter ranges, the ultrasonic displacement of the capillary was monitored. For all possible combinations of bond force and bond power, the ultrasonic displacement of the capillary increased with increasing bond power, without drastic changes caused by bond force changes. This indicated that the selected process window was located in a stable region. 相似文献
50.
This paper reports the results of current fundamental research at the Department of Process Engineering, University of Miskolc on the processing of clean coal from Mecsek bituminous coal, Southern Hungary. The theoretical possibility of the separation of different petrographic components was proven experimentally and their liberation degree was determined based on the petrographic composition, flotation kinetic study of isolated components (groups of components), scanning electron microscopy and microprobe analyses. The mill with stirred ball media was chosen for the ultra-fine liberation of the coal components. It was revealed that along with the liberation of coal components, their surface oxidation and spontaneous agglomeration, entrapping the mineral impurities take place in ultra-fine grinding. This paper discusses the interfacial phenomena occurring in the ultra-fine grinding process and their influence on the flotation. The concept for the advanced preparation of clean coal was developed, tested and proved. The main steps of this concept are the ultra-fine liberation in the stirred-media mill, the de-agglomeration of flocs spontaneously formed during the ultra-fine grinding and the induced (hydrophobic) flocculation with the following two-step flotation in a flotation column. 相似文献