Shock-induced cracks in molybdenum sheet

Abstract

Intergranular cracks occurred in shock-loaded molybdenum for specimens of grain size 17 μm and larger; for smaller grain size specimens (<17 μm) there was almost no crack initiation except in very thin specimens with shock loading of high pressure and long pulse duration. Cracks were not nucleated by twin barriers, and grain-boundary ledges appear to be responsible for initiating and propagating the cracks. The crack density was observed to decrease with increasing grain size for both constant peak pressure and pulse duration. In addition, crack density, as measured by the crack length intersecting the unit area of surface, generally increased with increasing shock pressure at constant pulse duration and with increasing pulse duration, at constant shock pressure.