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研究了加热温度、初火次变形率、退火温度等工艺参数对大尺寸Mo-1板组织和性能的影响.按照实验设计的4种热轧方案和工艺流程,采用350mm二辊不可逆式轧机和马弗炉对Mo-1板坯进行热轧、退火及温轧、冷轧实验;用金相显微镜观察了热轧及退火的组织;测试了0.2mm厚的成品钼板力学性能.结果表明,轧制温度选在1 250℃,初火次加工率选为37.5%,加工的Mo-1板综合性能比较好;热轧后的中间退火直接决定着后续工序的成败,退火温度应控制在850℃左右,保温时间应小于60min;为了减少热轧板坯表面和内部温差,改善板材组织和性能的各向异性,热轧时应预热轧辊,预热温度为200~300℃;采用换向轧制可提高板材的塑性、冲击韧性等,各向异性明显降低. 相似文献
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金属钼是一种硬而坚韧的难熔金属,熔点高达2620℃,具有良好的耐腐蚀、抗蠕变和抗热震性,被广泛应用于航空航天、核工业及电子产业.钼及钼合金常通过粉末冶金制备,避免传统工艺制备工序复杂的同时保证了钼及钼合金的成分及成品质量.其体心立方结构和塑脆转变温度高,严重影响了钼和钼合金的成型加工性能及由资源向钼成品转化的经济效益.成型加工中常使用锻造和轧制手段进行变形,但是会造成严重的加工硬化.热处理工艺能简单有效地改善钼金属在加工过程中的残余应力、加工硬化等不利影响,提升产品的质量与性能.钼合金变形过程中,单向轧制时会产生{111}织构,在较高的变形量下,织构发生偏转,转至{112}<110>;交叉轧制时趋向{100}织构.轧制变形量为40%~90%,1200℃退火处理后钼合金板材均会完成再结晶,当温度升至1250℃以上时晶粒变得粗大,无论是单向轧制织构还是再结晶期间织构转化时<110>织构均会存在.加热速率较快(>100 K/min)的情况下,钼合金的晶粒尺寸更细小.钼中掺入Ti、Zr、La等元素,会在亚晶界或晶界处形成碳化物或氧化物,改变微观组织,提升了再结晶温度,热处理后断裂方式从脆性断裂转变为韧性解理断裂,提升了钼合金的综合力学性能.本文综述了纯钼和钼合金板材的变形量、热处理工艺参数对其组织和性能影响的研究,对简化、有效生产高质量的钼板材过程给予理论指导,同时削减热处理能耗,有助于发展绿色热处理技术,并对未来钼板材热处理研究方向提出了展望. 相似文献
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《材料导报》2020,(Z1)
本工作探讨了几种热轧工艺参数对合金晶粒组织、超声波探伤噪音及力学性能的影响。研究结果表明:热轧道次及终轧温度对合金的晶粒组织、超声波探伤噪音都有一定的影响。经15道次热轧处理,终轧温度越高,合金的晶粒尺寸分布越不均匀,力学性能偏低,超声波探伤噪音严重。经35道次热轧处理,终轧温度较低时合金可获得细小均匀的晶粒,力学性能较优,提高终轧温度后晶粒不均匀长大,合金力学性能变差且出现超声波探伤噪音问题。由此可知,大尺寸铸锭经多道次热轧(终轧温度为300℃)后,经固溶淬火、2.5%预拉伸、自然时效96 h处理后,晶粒尺寸变得细小均匀,获得较高的力学性能,并且未出现超声波探伤噪音问题。 相似文献
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目的研究大变形量热轧、累积叠轧和普通热轧3种不同加工工艺及后续热处理对AZ31镁合金的组织及室温力学性能的影响。方法将均匀化处理后的AZ31原始样品采用大变形热轧、累积叠轧和普通热轧3种不同加工工艺制备成板材,并进行了后续热处理。利用EBSD技术和力学性能测试,解释了其组织和性能的关系。结果剧烈塑性变形工艺及适宜的热处理工艺,可使AZ31镁合金保持高强度的同时还可兼顾优良的室温延伸率。大变形量热轧工艺制备的AZ31镁合金板材的细晶组织及室温拉伸性能,可与累积叠轧等传统剧烈塑性变形工艺相媲美,屈服强度达到289 MPa,延伸率为7%。结论与普通热轧工艺制得的AZ31镁合金板材相比,大变形量热轧工艺及累积叠轧工艺制得的板材具有更高的强度和塑性。剧烈塑性变形镁合金在低温退火后获得的混晶组织,具有优良的综合力学性能,强度比形变态样品略低,而塑性与完全退火样品相同甚至更好。 相似文献
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A. M. Grishin 《Journal of Engineering Physics and Thermophysics》2001,74(4):895-903
Basic definitions and concepts of the physicomathematical theory of natural catastrophes are given. Possibilities of mathematical modeling of natural and technogenic catastrophes are discussed in the context of the theory of heat and mass transfer and the mechanics of reacting media. The importance of taking into account conjugate heat and mass exchange in modeling catastrophes is emphasized. A formula for evaluating the probability of a collisional catastrophe is given. 相似文献
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Velev JP Jaswal SS Tsymbal EY 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2011,369(1948):3069-3097
The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions. 相似文献
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Garny A Nickerson DP Cooper J Weber dos Santos R Miller AK McKeever S Nielsen PM Hunter PJ 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2008,366(1878):3017-3043
We have, in the last few years, witnessed the development and availability of an ever increasing number of computer models that describe complex biological structures and processes. The multi-scale and multi-physics nature of these models makes their development particularly challenging, not only from a biological or biophysical viewpoint but also from a mathematical and computational perspective. In addition, the issue of sharing and reusing such models has proved to be particularly problematic, with the published models often lacking information that is required to accurately reproduce the published results. The International Union of Physiological Sciences Physiome Project was launched in 1997 with the aim of tackling the aforementioned issues by providing a framework for the modelling of the human body. As part of this initiative, the specifications of the CellML mark-up language were released in 2001. Now, more than 7 years later, the time has come to assess the situation, in particular with regard to the tools and techniques that are now available to the modelling community. Thus, after introducing CellML, we review and discuss existing editors, validators, online repository, code generators and simulation environments, as well as the CellML Application Program Interface. We also address possible future directions including the need for additional mark-up languages. 相似文献
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Wiwanitkit V 《Hemodialysis international. International Symposium on Home Hemodialysis》2012,16(1):116; author reply 116-116; author reply 117
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热交换器是将不同温度介质之间的热量通过热传导的形式,由高温介质传递给低温介质,使介质达到生产所需温度的工艺设备,也可作为一种节能设备使用.通过对不同热交换器的结构分析,总结不同热交换器的优缺点、适用环境,为生产工艺设计人员及设备制造单位在选择可降低能耗、提高效率的设备上提供参考. 相似文献
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