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对α-β两相钛合金棒材中发现的偏析缺陷进行了分析,并提出了减少或消除偏析缺陷的解决措施。结果表明:α-β两相钛合金棒材中的偏析缺陷一般以亮斑形式存在;偏析可分为间隙元素偏析和主合金化学成分偏析两大类,主合金化学成分偏析又可以分为合金元素贫化、α相稳定元素(主要是铝)富化和β相稳定元素富化3种;棒材中偏析缺陷的产生一般与合金熔炼有关,为了减少或消除偏析,应加强配料过程中间合金选择、电极制备(混布料)、合金熔炼等工艺的控制,并注重各工序间的质量检验。 相似文献
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某医用TC4ELI钛合金板材在进行低倍检查时发现其存在贯穿的亮带缺陷,通过金相检验、扫描电镜分析、能谱分析和硬度测试,对缺陷种类和形成原因进行了分析。结果表明:该缺陷为富钛+间隙元素偏析缺陷,是由钛合金铸锭生产过程中海绵钛粒度不均匀、中间合金混料分布不均匀导致的;建议通过控制原料和熔炼工艺来减少或消除该缺陷。 相似文献
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TC4钛合金低倍组织中经常有亮条缺陷,从而引起航天产品的失效,本文对亮条的断口特征,金相组织,化学成分和显微硬度进行了分析,证实亮条是原材料化学成分偏析,并讨论了亮条的产生原因和预防。 相似文献
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钛合金冶金缺陷实例分析 总被引:2,自引:0,他引:2
对在工程实践中遇到的部分钛合金冶金缺陷实例进行了总结分析,并提出了相应的预防解决措施。实例分析结果表明:钛合金冶金缺陷形式主要有硬a缺陷、夹杂物、偏析、孔洞等。这些冶金缺陷主要是在钛合金的真空自耗熔炼过程中形成并遗传下的,且基本上可以通过提高原材料品质和改进熔炼工艺加以控制或消除。 相似文献
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TC9钛合金模锻叶片热加工变形是钛合金热加工的一大关键。本文研究锻造和热处理综合条件对钛合金热加工变形的影响,并提出防止或减少叶片变形的措施及变形校正需要注意的问题。这些对钛合金叶片的热加工提供了宝贵的经验。 相似文献
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四、真空应用 A1 真空电弧和真空双电极电弧 熔炼钛合金锭组织的比较──研究直接 利用铸钛作为等温锻造坯料的可能性许嘉龙 (上海钢铁研究所) 张志超 (上海钢铁研究所)方平伟 (上海钢铁研究所)胡五玉 (上海钢铁研究所) 真空双电极电弧熔炼(VADER)是一种新的真空熔炼工艺,利用此法熔炼的高温合金锭子具有细小、均匀的等轴组织,减少了偏析,提高了热加工性能。本文比较了真空电弧和真空双电极电弧熔炼 Ti-10V-2Fe-3Al和Ti-6Al-4V锭子的组织。结果表明真空双电极电弧熔炼的钦合金锭子也具有细小、均匀的等轴组织,大大改善了宏观和微观偏… 相似文献
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TC4钛合金棒料亮条纹缺陷分析 总被引:1,自引:0,他引:1
某TC4钛合金棒料加工产品,在进行X射线检测时发现存在亮条纹缺陷,采用各种理化检验手段,分析了该TC4钛合金棒料的化学成分、显微组织和硬度。结果表明:该TC4钛合金棒料在冶炼时由于工艺控制不当,形成了一个严重的富钛贫铝贫钒区域,该区域在后期的热加工过程中形成了不同于基体的粗大单相α组织,其硬度明显低于基体硬度,所以X射线检测时呈现亮条纹形貌;这是一种典型的软偏析冶金缺陷。 相似文献
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着重研究了TA5钛合金锻造工艺对组织与性能的影响.采用二次真空熔炼熔铸的α/α+β转变温度为990~1 000℃的TA5钛合金,在β相区开坯,经多火次中间锻造后,对其最后一火次的锻造,改变锻造温度和变形量共8种工艺方案进行实验,考察锻造温度和变形率对组织和性能的影响.结果表明:①最后一火次在970℃(α相区)锻造变形,得到的组织为等轴α组织,在1 020℃(β相区)变形得到的组织以粗大的片状α组织为主;②锻造变形率对TA5钛合金的拉伸性能影响不明显;③锻造温度对冲击韧性aK影响较大,成品锻造在β相区变形的aK值均高于α相区的水平. 相似文献
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介绍了在机械压力机上实现精密锻造的模具工装结构特点、精密锻造原理以及TC4钛合金玻璃润滑剂的防护特点;采用α+β锻、β锻2种不同锻造工艺方案成功地实现了TC4钛合金人工髋关节和汽车连杆的精密模锻,并分析了不同锻造工艺对锻件组织和机械性能的影响. 相似文献
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Production planning and scheduling are becoming the core of production management, which support the decision of a petrochemical company. The optimization of production planning and scheduling is attempted by every refinery because it gains additional profit and stabilizes the daily production. The optimization problem considered in industry and academic research is of different levels of realism and complexity, thus increasing the gap. Operation research with mathematical programming is a conventional approach used to address the planning and scheduling problem. Additionally, modeling the processes, objectives, and constraints and developing the optimization algorithms are significant for industry and research. This paper introduces the perspective of production planning and scheduling from the development viewpoint. 相似文献
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目的 探索江门世遗文化的传承、发展和转化的新思路,践行国家在《粤港澳大湾区发展规划》纲要中要求江门承担与港澳地区文化创意合作与开发任务的分工。方法 与澳门高校紧密合作,开展专业培训课程,以开平碉楼为例,从人文视角开展设计研究,梳理开平碉楼的文化脉络,把世遗文化的元素和其背后的文化融入文创产品中,提升文创产品的附加值,推动当地文创产业结构的变革。结果 两地高校构建了稳定的科研团队,开设长期有效的设计培训课程,与景区建立了研究协作关系,帮助景区构建了一套产销研的商业模式。结论 以跨区域高校合作为平台,以文创产品为抓手,依托江澳两地的资源优势,可以构建江门世遗文化全新的品牌形象,最终推动开平世遗文化的活化。 相似文献
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Masao Doyama 《Bulletin of Materials Science》1999,22(3):723-728
By making a step on one surface (
) of a rectangular small paralellepiped copper crystal, dislocations could be created by the molecular dynamic method. The
dislocation created was not a complete edge dislocation but a pair of Heidenreich-Shockley partial dislocations. Each time
a dislocation was created, the stress on the surface was released. Small copper crystals having a notch were pulled (until
fracture), compressed and buckled by use of the molecular dynamic method. An embedded atom potential was used to represent
the interaction between atoms. Dislocations were created near the tip of the notch. A very sharp yield stress was observed.
The results of high speed deformations of pure silicon small crystals using the molecular dynamics are presented. The results
suggest that plastic deformation may be possible for the silicon with a high speed deformation even at room temperature. Another
small size single crystal, the same size and the same surfaces, was compressed using molecular dynamic method. The surfaces
are {110}, {112} and {111}. The compressed direction was [111]. It was found that silicon crystals are possible to be compressed
with a high speed deformation. This may suggest that silicon may be plastically deformed with high speed deformation. 相似文献
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Albert C. Parr 《Journal of research of the National Institute of Standards and Technology》2001,106(1):151-186
The national measurement system for photometric and radiometric quantities is presently based upon techniques that make these quantities traceable to a high-accuracy cryogenic radiometer. The redefinition of the candela in 1979 provided the opportunity for national measurement laboratories to base their photometric measurements on optical detector technology rather than on the emission from high-temperature blackbody optical sources. The ensuing technical developments of the past 20 years, including the significant improvements in cryogenic radiometer performance, have provided the opportunity to place the fundamental maintenance of photometric quantities upon absolute detector based technology as was allowed by the 1979 redefinition. Additionally, the development of improved photodetectors has had a significant impact on the methodology in most of the radiometric measurement areas. This paper will review the status of the NIST implementation of the technical changes mandated by the 1979 redefinition of the candela and its effect upon the maintenance and dissemination of optical radiation measurements. 相似文献
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Error and uncertainty in modeling and simulation 总被引:1,自引:0,他引:1
William L. Oberkampf Sharon M. DeLand Brian M. Rutherford Kathleen V. Diegert Kenneth F. Alvin 《Reliability Engineering & System Safety》2002,75(3)
This article develops a general framework for identifying error and uncertainty in computational simulations that deal with the numerical solution of a set of partial differential equations (PDEs). A comprehensive, new view of the general phases of modeling and simulation is proposed, consisting of the following phases: conceptual modeling of the physical system, mathematical modeling of the conceptual model, discretization and algorithm selection for the mathematical model, computer programming of the discrete model, numerical solution of the computer program model, and representation of the numerical solution. Our view incorporates the modeling and simulation phases that are recognized in the systems engineering and operations research communities, but it adds phases that are specific to the numerical solution of PDEs. In each of these phases, general sources of uncertainty, both aleatory and epistemic, and error are identified. Our general framework is applicable to any numerical discretization procedure for solving ODEs or PDEs. To demonstrate this framework, we describe a system-level example: the flight of an unguided, rocket-boosted, aircraft-launched missile. This example is discussed in detail at each of the six phases of modeling and simulation. Two alternative models of the flight dynamics are considered, along with aleatory uncertainty of the initial mass of the missile and epistemic uncertainty in the thrust of the rocket motor. We also investigate the interaction of modeling uncertainties and numerical integration error in the solution of the ordinary differential equations for the flight dynamics. 相似文献
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New measurements are reported for the density and viscosity of tetralin and trans-decalin. The density was determined from room temperature to 60°C for tetralin and to 95°C for trans-decalin. The kinematic viscosity was measured up to temperatures slightly above 100°C. Our results improve upon the values recommended by the American Petroleum Institute for these liquids. 相似文献