Dynamic Yielding and Spall Behavior of Commercially Pure Grade 4 Titanium

ORAL

Abstract

The dynamic yielding and fracture (spalling) of commercially pure (grade 4) titanium are investigated using symmetric plate impact experiments over a peak stress range of 5.6 GPa to 12.5 GPa, using the 80-mm single-stage gas-gun. VISAR rear free surface velocity profiles display both a Hugoniot elastic limit (HEL) and a velocity pullback, which are indicative of dynamic compressive yielding and tensile fracture (spalling), respectively. The HEL values appear to show a slight decrease with peak stress from 2.2 GPa to 2.0 GPa along with a corresponding increase in twinning observed in recovered impacted samples. The spall strength on the other hand increases with peak stress from a value of 3.3 GPa to 3.8 GPa and shows a good power law fit with the decompression strain rate. The differing responses in dynamic yield and fracture behavior suggest that void nucleation may be the dominant mechanism affecting the spall strength of grade 4 titanium.

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Authors

  • Naresh Thadhani

    • Georgia Institute of Technology
    • Georgia Institute of Techhnology

  • R.L. Whelchel

    • Georgia Institute of Techhnology

  • Tom Sanders

    • Georgia Institute of Techhnology

  • D.S. Mehkote

    • Johns Hopkins University, Applied Physics Lab

  • K.A. Iyer

    • Johns Hopkins University, Applied Physics Lab