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首页> 外文学位 >Creep, fatigue, and deformation of alpha and alpha-beta titanium alloys at ambient temperature.
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Creep, fatigue, and deformation of alpha and alpha-beta titanium alloys at ambient temperature.

机译：在室温下，α和β钛合金的蠕变，疲劳和变形。

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摘要

Titanium and it alloys are extensively utilized in critical applications that require materials with high strength to weight ratios, rigidities, and toughnesses. This being the case, over 70 years of research have been devoted to the measurement, understanding, and tailoring of the mechanical properties of these alloys. Despite these efforts, surveys of the current knowledge base and understanding of the mechanical responses of Ti alloys demonstrate that numerous mechanical behaviors have yet to be investigated and explained.;It has been noted, but generally not appreciated, that commercially important materials display modest strength differentials near room temperature when deformed under quasi-static loading conditions at modest rates (∼10 -5 to 10-3 s-1 ). Under static loading, subtle variations in plastic flow behavior leads to dramatically weaker materials when loaded in tension versus compression. The asymmetric material responses of single and two-phase alloys deformed under monotonic constant rate and creep conditions have been investigated and related to the fundamental slip behavior observed in single crystalline materials.;Two-phase titanium alloys containing a majority volume fraction of the alpha (HCP) phase have long been known to undergo creep deformation at lower temperatures (T Tm) and stresses (sigma sigmays). The time dependence of this plasticity, stemming from a> slip in the alpha-phase, has been found to be sensitive to microstructural condition. The nature of low temperature creep in heat-treatment modified beta-annealed Ti-6Al-2Sn-4Zr-2Mo has been investigated. Microstructural features, particularly primary alpha-lathe and beta-rib structure (secondary alpha morphology and content), were systematically modified, and the resulting structures were deformed under both creep and constant strain rate loading conditions. Variations in plastic response are discussed in terms of strain hardening and strain rate sensitivity parameters.;The mechanical performance of engineering Ti alloys has long been known to be sensitive to the to nature of applied load waveform. A review of the open literature elucidates several gaping holes in the current understanding of waveform induced plastic response of cyclically loaded materials. This study addresses several of those issues. Sustained load hold time effects during the fatigue an aalpha-Ti alloy is investigated with respect to loading conditions and slip planarity and compared to cyclic fatigue and creep responses at room temperature.
机译：钛及其合金广泛用于要求高强度重量比，刚度和韧性的材料的关键应用中。在这种情况下，超过70年的研究致力于测量，理解和定制这些合金的机械性能。尽管做出了这些努力，但对当前知识库的调查以及对Ti合金力学响应的理解表明，尚有许多力学行为尚待研究和解释。已经注意到，但通常没有意识到，具有商业价值的材料显示出适度的强度在准静态载荷条件下以适度的速率（〜10 -5到10-3 s-1）变形时，接近室温时的压差。在静态载荷下，当以拉伸与压缩方式加载时，塑性流动行为的细微变化会导致材料的强度大大降低。已经研究了在单调恒定速率和蠕变条件下变形的单相和两相合金的不对称材料响应，并且与在单晶材料中观察到的基本滑移行为有关。;包含大部分体积分数为α（长期以来，HCP）相在较低温度（T 滑移，对微结构条件很敏感。已经研究了热处理改性的β退火Ti-6Al-2Sn-4Zr-2Mo的低温蠕变性质。微观结构特征，特别是主要的α车床和beta-rib结构（次要的α形态和含量），被系统地修改，并且得到的结构在蠕变和恒定应变率加载条件下均发生变形。根据应变硬化和应变速率敏感度参数讨论了塑性响应的变化。长期以来，已知工程钛合金的机械性能对所施加载荷波形的性质敏感。对开放文献的回顾阐明了当前对周期性加载材料的波形感应塑性响应的理解中的几个空白。这项研究解决了其中一些问题。在疲劳条件下，研究了α-Ti合金在载荷条件和滑移平面度方面的持续载荷保持时间效应，并将其与室温下的循环疲劳和蠕变响应进行了比较。

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  • 作者

    Brandes, Matt.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Engineering Metallurgy.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 471 p.
  • 总页数 471
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 冶金工业;工程材料学;
  • 关键词

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