STP1323

    Sensing Crack Nucleation and Growth in Hard Alpha Defects Embedded in Ti-6A1-4V Alloy

    Published: Jan 2001


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    Abstract

    The cracking behavior of nitrogen-rich hard alpha anomalies in Ti-6A1-4V is examined for partially validating predictive approaches used in life management of high energy rotors. Both synthetic and naturally occurring anomalies were subjected to static and fatigue loading. An internal defect, completely surrounded by Ti-6-4 material, was much more resistant to cracking when contrasted to a surface-connected defect. Furthermore, acoustic emission and electric potential drop methods were effective indicators of cracking, especially progression from the defect and into the base metal. Consistent signals were observed for each type of transducer, although the acoustic emission signals were more robust from an interpretative standpoint. Analysis of the acoustic emission data provided good quantitative estimates of crack size.

    Keywords:

    fatigue, damage, acoustic emission, potential drop, mechanical testing, hard alpha defect


    Author Information:

    McKeighan, P. C.
    Manager, Engineering Technologist and Manager, Southwest Research Institute, San Antonio, TX

    Nicholls, A. E.
    Manager, Engineering Technologist and Manager, Southwest Research Institute, San Antonio, TX

    Perocchi, L. C.
    Metallurgical Specialist, General Electric Corporate Research and Development, Schenectady, NY

    McClung, R. C.
    Manager, Engineering Technologist and Manager, Southwest Research Institute, San Antonio, TX


    Paper ID: STP42139S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP42139S


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