• Login
    View Item 
    •   Home
    • Theses & Dissertations
    • 2017 - Mines Theses & Dissertations
    • View Item
    •   Home
    • Theses & Dissertations
    • 2017 - Mines Theses & Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Mines RepositoryCommunitiesPublication DateAuthorsTitlesSubjectsThis CollectionPublication DateAuthorsTitlesSubjects

    My Account

    Login

    Mines Links

    Arthur Lakes LibraryColorado School of Mines

    Statistics

    Display Statistics

    Effects of thermal processing variations on microstructure and high cycle fatigue of beta-STOA Ti-6Al-4V

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    McArthur_mines_0052N_11423.pdf
    Size:
    4.869Mb
    Format:
    PDF
    Download
    Author
    McArthur, Byron
    Advisor
    Kaufman, Michael J.
    Clarke, Amy
    Date issued
    2017
    Keywords
    heat treating
    titanium
    microstructure
    fatigue
    
    Metadata
    Show full item record
    URI
    https://hdl.handle.net/11124/172049
    Abstract
    Titanium alloys are often used in fatigue-limited structural applications within the aerospace industry. Because of the primary processing control and reactivity of titanium, the fatigue life of the material is predominantly dependent upon the α-phase microstructure, rather than internal defects such as voids or inclusions. For titanium alloy Ti – 6 wt % aluminum - 4 wt % vanadium (Ti-6Al-4V), the influence of cooling rate from above the ß-transus is known to affect the resulting microstructure and influence high cycle fatigue life. The transfer time from the furnace to the water-quenching bath significantly influences the cooling rate, and thus controls the microstructural development and fatigue properties. A hydraulic actuator produced from a Ti-6Al-4V forging failed prematurely during fatigue testing, and provided the industrial motivation for this work. A quench dilatometer was used, along with subsequent scanning electron microscopy, to explore the microstructural variations produced as a function of thermal history. Rotating bending fatigue testing in the high cycle fatigue regime highlighted a two orders of magnitude reduction in fatigue life due to an increased quenching transfer time. The increased quench transfer time was shown to create packets of co-oriented α laths that facilitated crack initiation. Fatigue crack growth rate measurements were also used to quantify post-initiation crack growth rates in microstructures produced by different quench delay times. Long crack growth rates were found to be similar for short and long quench delay times. Post-mortem fractographic analysis and electron back scattered diffraction aided in determining the microstructural influence on fatigue crack initiation and propagation, indicating that long, planar basal slip lengths contribute to crack nucleation. Based upon these findings, it is found that even minor variations in quench transfer time can significantly influence the high cycle fatigue life of titanium alloys.
    Rights
    Copyright of the original work is retained by the author.
    Collections
    2017 - Mines Theses & Dissertations

    entitlement

     
    DSpace software (copyright © 2002 - 2023)  DuraSpace
    Quick Guide | Contact Us
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.