Deformation twins in oriented, columnar-grained tungsten rod ballistic penetrators

Deformation twins coincident with traces of {211} planes in sections cut fr om [001], [011], and [111] columnar-grained tungsten rod ballistic penetrat ors in rolled homogeneous armor targets have been identified by transmissio n electron microscopy and selected-area electron diffraction. These twins h ave been shown to coincide with Neumann bands observed by optical metallogr aphy. In addition, the twin density appears to increase at the head of the projectile and twins are observed to coincide with flow features which are characterized by dynamic recovery and recrystallization which provide the f low mechanism. Since deformation twins appear to play a prominent role in c olumnar and single-crystal tungsten rod flow, and twinning is limited by gr ain size, sintered or polycrystalline tungsten or tungsten alloy penetrator s cannot be expected to perform like single crystal penetrators and penetra tor strategies may need to focus on inducing twinning or in developing supe rplastic behavior. (C) 2001 Elsevier Science B.V. All rights reserved.