The purpose of this research was to evaluate the ability of three austempered cast iron materials to resist ballistic impact. The designations for these materials were malleable 600, ductile 600 and ductile 650 irons. In a prior program (Part 1, paper 96-65) on ballistic impact on 10 different cast iron materials, it was found that certain austempered ductile iron and austempered malleable iron materials had higher values of hydrodynamic mode energy E than did rolled homogeneous armor steel (RHA) and certain surrogates of RHA, such as hardened wrought 4340 steel. The hydrodynamic mode energy E represents the energy per unit mass of target material required to cause the metal to flow under impact conditions. Austempered ductile 600 iron is the most effective armor material of the three materials investigated in this program. It has the highest value of hydrodynamic mode energy E and it provides more protection against a long rod penetrator than either the ductile 650 or the malleable 600 materials. The hydrodynamic mode energy E for the ductile 600 iron is 5 % higher than that for rolled homogeneous armor steel. Austempered ductile 600 iron requires 11 % less weight and approximately the same thickness as hardened, wrought 4340 steel to defeat a typical long rod kinetic energy penetrator. Austempered iron materials exhibit brittle failure to varying degrees and significant rear surface spall. Of the three materials tested, the most brittle is the malleable 600, while the least brittle is the ductile 650. Potential areas for future study include gradient-property austempered iron armor. Since the results of the programs indicate that austempered ductile iron can absorb more energy per unit mass than conventional wrought steel armor, but that austempered iron exhibits brittle failure and spall, a gradient property armor in which a high-E austempered iron is combined with a ductile back face could be an effective armor. Experiments and analyses would be required to determine the optimum combination of materials and the performance advantages of such armors relative to monolithic steel armor.
Ballistic evaluation. Part 2. Austempered malleable and austempered ductile irons
Ballistische Bewertung von Ersatzwerkstoffen für Panzerstahl. Teil 2. bainitisches Gußeisen mit Kugelgraphit und bainitischer Temperguß
1996
9 Seiten, 17 Bilder, 3 Tabellen, 24 Quellen
Aufsatz (Konferenz)
Englisch
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