Explosive fragmentation of additively manufactured stainless steel
ORAL
Abstract
The role of porosity on explosively driven fragmentation is examined in an additively manufactured stainless steel spherical shell with artificially implanted internal pores. Pore arrays with various spacings were built into the shell during manufacture. This shell is driven by an insensitive high explosive, resulting in high strain rate deformation (>8000/s) and failure of the stainless steel shell. Photonic Doppler velocimetry measures the expansion rate; dynamic x-ray radiography and high-speed optical imaging capture the fracture behavior of the stainless steel. The fracture response of the additively manufactured 316L stainless steel shell with internal pores is compared to published experimental results on the same material with surface defects [1]. Previous published results with surface defects indicate that, while these defects initiate fracture, the shell fragment size is not affected when the surface defects are closely spaced relative to the Mott release wave travel distance. In the current experiment, we observe that, (1) similar to surface defects, large internal pores nucleate fracture, (2) fragment shape and size are affected by internal defects if they are spaced within a critical distance, defined by Mott wave distance, from one another, and (3) early fracture due to internal defects occurs during shell acceleration yielding larger fragment mass than produced by natural fragmentation, in accordance with Grady’s analytical theory. This study illustrates how laser powder bed fusion additive manufacturing can be leveraged to study factors affecting fragmentation in a controlled manner.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence
Livermore National Laboratory under Contract DE-AC52-07NA27344. This abstract has been assigned the release ID# LLNL-ABS-2002325.
1. Callahan, M., et al., Explosive fragmentation of additively manufactured stainless steel. Journal of Applied Physics, 2023. 134(15): p. 1-14.
–
Publication: A. Wu, M. Skeate, M. Lund, M. Linne, B. Friedman, G. Glendinning, G. H. Campbell, K. Mickelson, B. Fuller, S. Burke, H.-S. Park (in preparation) Explosive fragmentation of additively manufactured stainless steel with architected porosity.
