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Mechanical properties of 50Molybdenum-50Rhenium alloys and their assembly by spinal muscular atrophy.

机译：50钼50 hen合金的力学性能及其通过脊柱肌肉萎缩的组装。

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摘要

This study is concerned with the deformation and fracture behaviors, especially strain-rate effect on plasticity in tensile tests, of two 50Mo-50Re alloys at strain rates ranging from 10-6 s-1 to 1 s-1 at room temperature in air. Metallographic observations of the 50Mo-50Re alloys before and after tensile deformation were conducted to understand the relationships among mechanical properties, microstructure and strain rate in these alloys. Understanding the strain-rate effect on mechanical properties of 50Mo-50Re alloys is important for optimizing forming operations, especially sheet forming, of these alloys, which are often used in cathode and aerospace applications.;An anomalous strain-rate effect on ductility was observed in the 50Mo-50Re alloys. Ductility was significantly increased by increasing the strain rate from 10-6 s-1 to 1 s-1 in the fully-recrystallized and recovery heat-treated 50Mo-50Re alloys in tension at room temperature. At a low strain rate, fracture was predominantly brittle, while it was more ductile at higher stain rates. At a low strain rate, secondary cracks initiated at grain boundaries and triple junctions were observed in these alloys, which suggested that significant stress concentration was generated by tensile plastic deformation in the vicinity of grain boundaries, especially triple junctions. Electron backscatter diffraction experiments revealed that there was strain concentration at grain boundaries and their triple junctions during tensile deformation in these alloys. The decrease in ductility at low strain rates in the alloys was related to the possible interaction between dislocations and trace interstitial atoms (e.g., H, O, N and C) picked up during production of these alloys.;This dissertation also reports the research efforts made to optimize small-scale resistance spot welding (SSRSW) of refractory alloy 50Mo-50Re thin sheet by adjusting seven important welding parameters, including hold time, electrode material, electrode shape, ramp time, weld current, electrode force, and weld time. The strength of the weld was improved from 100 N to 184.7 N after the optimization. The improved welding quality gave rise to the overall quality improvement of the traveling tubes for microwave telecommunication industry. The diameter of nuggets and formation of pores were also discussed in the study.;KEYWORDS: Mechanical properties, Refractory alloy, Mo-Re alloy, Strain rate, Resistance spot welding.
机译：这项研究涉及两种50Mo-50Re合金在室温和空气中的应变速率范围从10-6 s-1到1 s-1的变形和断裂行为，尤其是应变率对拉伸试验中塑性的影响。进行了50Mo-50Re合金拉伸变形前后的金相观察，以了解这些合金的力学性能，微观结构和应变率之间的关系。了解应变率对50Mo-50Re合金力学性能的影响对于优化这些合金的成型操作（尤其是片材成型）非常重要，这些合金通常用于阴极和航空航天应用中;观察到对延性的异常应变率效应在50Mo-50Re合金中。通过在室温下以张力将完全重结晶和恢复热处理的50Mo-50Re合金中的应变速率从10-6 s-1增加到1 s-1，可大大提高延展性。在低应变率下，骨折主要为脆性，而在较高的染色率下则更易延展。在低应变速率下，在这些合金中观察到在晶界和三重结处引发的二次裂纹，这表明在晶界附近，特别是三重结处，拉伸塑性变形产生了显着的应力集中。电子背散射衍射实验表明，在这些合金的拉伸变形过程中，在晶界及其三重结处存在应变集中。合金在低应变率下延展性的下降与位错与这些合金生产过程中吸收的痕量间隙原子（例如H，O，N和C）之间可能的相互作用有关。通过调整七个重要的焊接参数来优化耐火合金50Mo-50Re薄板的小规模电阻点焊（SSRSW），包括保持时间，电极材料，电极形状，倾斜时间，焊接电流，电极力和焊接时间。优化后，焊缝强度从100 N提高到184.7N。焊接质量的提高引起了微波通信行业活动管整体质量的提高。研究中还讨论了熔核的直径和孔的形成。关键词：力学性能，耐火合金，Mo-Re合金，应变率，电阻点焊。

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  • 作者

    Xu, Jianhui.;

  • 作者单位

    University of Kentucky.;

  • 授予单位 University of Kentucky.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 158 p.
  • 总页数 158
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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