Microstructural modifications in -brass targets after small charge explosions

Firrao, Donato; Matteis, Paolo; Pozzi, Chiara; Ienco, M. G.; Pellati, G.; Pinasco, M. R.; Montanari, Roberto; Tata, Maria Elisa

doi:10.1016/j.calphad.2008.09.016

Cited by 2 publications

(6 citation statements)

References 18 publications

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“…Thus, the present study was aimed to single out the threshold conditions of detectability of crystallographic alterations, and to study the possible transition between slip and twinning. Whereas most results were reported in previous papers [3][4][5][6], each addressing in detail one or two alloys, the present work presents a comprehensive review of the most significant findings.…”

Section: Introductionmentioning

confidence: 64%

“…Since from OM analysis it is not possible to distinguish between slip and twin traces, analyses with Scanning Electron Microscopy (SEM) coupled with Electron Backscattered Diffraction (EBSD) were planned. A first scan on α-brass did not show different crystal orientations in areas with parallel deformation marks, but was not conclusive due to a relatively large step size (about 10 µm/step) [6]. Further scans on a gold sample, performed with a very small step size (100 nm) evidenced the parallel marks as narrow strips with a crystal orientation different from that of their parent grain [13].…”

Section: Resultsmentioning

confidence: 99%

“…All tested materials, except the aluminum alloy, were annealed; the stainless steel and the gold alloy were annealed at two different temperatures, yielding slightly different grain sizes (Table 1); the aluminum alloy samples were solubilized and aged. The alloy compositions and heat treatments were reported in more detail elsewhere [3][4][5][6]. All disks were grinded, polished and etched before the explosions, so that the exposed surface could be analyzed as such after the test, avoiding the risk of introducing artifacts not related to the explosive event.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The authors wish to thank their colleagues from University of Genova, University of Roma Tor Vergata, and Italian Navy who gave their contribution to the present research [3][4][5][6], as well as the Italian Ministry of University and Research for financial support by grant no. 200109974.…”

Section: Acknowledgementsmentioning

confidence: 99%

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Recent Developments on the Microstructural Effects Caused by Small-Charge Explosions in FCC Alloys

Firrao

Matteis

Pozzi

2010

MSF

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Abstract. Metals exposed to small charge explosions, even in absence of overall deformation, show characteristic and permanent microstructural features, that can be related to blast wave properties, e.g. to the charge mass and the charge-to-target distance. In particular, Face Centered Cubic (FCC) alloys with low stacking fault energy may exhibit mechanical twinning due to the high strain rate caused by an explosion, even if in slower processes they mainly deform by slip. In some forensic science investigations, these crystallographic modifications, and particularly the occurrence of twinning, may be among the few remaining clues of a small charge explosion, and may be useful to hypothesize the nature and location of the charge. A wide experimental campaign was performed to correlate the blast wave properties with the ensuing modifications of FCC metal targets, and to investigate the microscopic deformation mechanisms leading to these modifications. In particular, it was attempted to identify the threshold conditions (charge-to-target distance, charge mass, and hence applied stress) that yield barely detectable microstructural modifications, and to study the transition from slip to twinning. FCC metal alloys, with low (α-brass, stainless steel), intermediate (copper, gold alloy), or high (aluminum alloy) stacking fault energy, were exposed to blast waves (caused by 50 or 100 g plastic explosive charges located at increasing charge-to-target distances) and then analyzed by X-ray diffraction, optical microscopy, scanning electron microscopy, and electron backscattered diffraction imaging. A comprehensive review of the most significant findings of the whole research, together with theoretical considerations on the slip and twinning deformation mechanisms, is here presented.

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Section: Introductionmentioning

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Acknowledgementsmentioning

confidence: 99%

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Recent Developments on the Microstructural Effects Caused by Small-Charge Explosions in FCC Alloys

Firrao

Matteis

Pozzi

2010

MSF

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“…The amount of carbides detected by SEM [20] generally decreases with increasing the aging duration and temperature (both for as-received and RHT materials). It is thought that the carbides formed during prior heat treatments are unstable at the aging temperature and dissolve, while undetected finer carbides, possibly with different compositions, are re-precipitated, thus causing the strengthening effects.…”

Section: Mechanical Propertiesmentioning

confidence: 93%