Shock Hardened and Annealed Type 316 Stainless Steel

Abstract

The structure of shock hardened Type 316 stainless steel has been examined by transmission electron microscopy in a number of different conditions involving variations in shock pressure, temperature, and post-shock annealing in an effort to correlate changes in mechanical properties with structural changes. The samples for microscopy were prepared by careful slicing from 1/2-inch-thick shock-hardened plate, the plane of the slice being parallel to the shock wave propagation direction. This was followed by dimpling in a 60 percent H3PO4-40 percent H2SO4 bath at 125 °C, and electrolytic polishing to break-through in the same solution at 70 °C.Increasing the shock wave pressure from 0 to 320 kbar at ambient temperature produced structures with increasing dislocation densities. At 80 kbar, the easily-resolvable dislocations were relatively straight and lay in arrays on{111} [-planes as shown in Figure 1. At the 320 kbar pressure level, twin-like features formed (Figure 2) and were accompanied by a fine dislocation structure consisting in part of a high concentration of dislocation loops.