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Creep, Fatigue, And Deformation Of Alpha And Alpha-Beta Titanium Alloys At Ambient Temperature

Brandes, Matt C.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1221848896

Abstract Details

2008, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
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 1/s). 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 (σ < σys). The time dependence of this plasticity, stemming from a-type 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 alpha-Ti alloy is investigated with respect to loading conditions and slip planarity and compared to cyclic fatigue and creep responses at room temperature.
Michael J. Mills, PhD (Advisor)
James C. Williams, PhD (Advisor)
Glenn S. Daehn, PhD (Committee Member)
Andrew P. Woodfield, PhD (Committee Member)
471 p.
Materials Science; Metallurgy
Titanium; creep; dwell fatigue; strength; core structure; facet; tenison compression asymmetry

Recommended Citations

Citations

  • Brandes, M. C. (2008). Creep, Fatigue, And Deformation Of Alpha And Alpha-Beta Titanium Alloys At Ambient Temperature [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1221848896

    APA Style (7th edition)

  • Brandes, Matt. Creep, Fatigue, And Deformation Of Alpha And Alpha-Beta Titanium Alloys At Ambient Temperature. 2008. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1221848896.

    MLA Style (8th edition)

  • Brandes, Matt. "Creep, Fatigue, And Deformation Of Alpha And Alpha-Beta Titanium Alloys At Ambient Temperature." Doctoral dissertation, Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1221848896

    Chicago Manual of Style (17th edition)

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© 2008, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.