Determination of Minimum Machining Depth After Heat Treatment of ASTM Grade 2 Titanium Alloy

Authors

  • Richard G. Dobeson,

    Corresponding author
    1. Defence Materials Technology Centre, School of Mechanical and Mining Engineering, The University of Queensland, Australia
    2. Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), The University of Queensland, Australia
    3. CAST CRC, School of Mechanical and Mining Engineering, The University of Queensland, Australia
    • Defence Materials Technology Centre, School of Mechanical and Mining Engineering, The University of Queensland, Australia.
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  • Stuart D. McDonald,

    1. Defence Materials Technology Centre, School of Mechanical and Mining Engineering, The University of Queensland, Australia
    2. Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), The University of Queensland, Australia
    3. CAST CRC, School of Mechanical and Mining Engineering, The University of Queensland, Australia
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  • Matthew S. Dargusch

    1. Defence Materials Technology Centre, School of Mechanical and Mining Engineering, The University of Queensland, Australia
    2. Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), The University of Queensland, Australia
    3. CAST CRC, School of Mechanical and Mining Engineering, The University of Queensland, Australia
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  • The authors gratefully acknowledge the CAST Cooperative Research Centre and Defence Materials Technology Centre for the financial support and permission to publish this work. The CAST Cooperative Research Centre was established and is supported under the Australian Government's Cooperative Research Centres Programme. The DMTC was established and is supported under the Australian Government's Defence Future Capability Technology Centres Programme.

Abstract

This paper reports on the development of a practical tool for determining minimum machining depths required after heat treatment of ASTM Grade 2 titanium alloys. Mechanical properties are adversely affected by the brittle alpha-case that develops when titanium and its alloys are exposed to oxygen at elevated temperatures. This layer is normally removed by machining prior to putting the component into service. The exact depth of material that is required to be removed is dependent on the combined time and temperature of any prior heat treatment. This paper presents a study of oxygen diffusion in ASTM Grade 2 titanium alloy that was performed to quantify the rate of alpha-case formation. A generalized method of predicting the depth of alpha-case is discussed and a nomogram has been developed and presented as a tool for determining the minimum amount of material that needs to be removed.

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