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Science and Technology of Energetic Materials

Vol.63, No.5 (2002)

Research paper

Spall behavior of steels under hypervelocity impact
Tatsumi Moritoh, Shohei Matsuoka, Toshiyuki Ogura, Kazutaka G. Nakamura, Ken-ichi Kondo, Masahide Katayama, and Masatake Yoshida
p.301-306

Abstract

We performed hypervelocity impact experiments on steel materials (SS400, SUS304, and SCM440) at velocities up to 9 km s-1. Microstructures and micro damages near a crater and on the spall plane were examined using optical microscopy and scannlng electron microscopy. The α - ε phase transition region was observed near the crater of SS400 and SCM440 samples recovered. Cracks which are parallel to the impact direction below the crater were observed, and radial cracks grew from the α - ε phase interface at high velocity impact tests. Cleavage was dominant mechanism for a spall fracture surface of both of SS400 and SCM440, while ductile fracture was observed at the fracture surface of SUS304. Geometric spall behaviors were compared with numerical simulations using hydrocode. Spall diameters were well reproduced by optimizing yield strength for each steel at high impact velocities, particularly above 6 km s-1. Spall strength was determined to be 1.1, 2.7, and 2.1 GPa for SS400, SUS304, and SCM440, respectively.

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