Thermal Recovery of Explosive Shock-loaded Stainless Steel

Abstract

The annealing response of shock-loaded type 304 stainless steel was studied in the pressure range of 120–1200 kbars, and compared with the response of stainless steel cold-rolled 5 and 45%. The annealing kinetics of shock-loaded stainless steel are characterized by a prominent recovery and grain growth stage, with little perceptible recrystallization in the classical sense. The results indicated a pronounoed structural difference between the shock-loaded and cold-rolled materials, as observed by transmission electron microscopy. The structure of stainless steel shock-loaded to 750 and 1200 kbars is observed to be strongly influenced by the transient shock heating effect, and a dislocation cell-type substructure is observed to occur predominantly in (100) grains. The hardness produced over the pressure range 120–1200 kbars by explosive shock-loading is shown to occur by a transition from dense dislocation arraya to twin-faults, and finally to what may be dense point defect concentrations at very high pressures (750–1200 kbars) where transient thermal recovery occurs. Cold-rolled hardening produces a transition from dense dislocation arrays to martensite at large reduction in thickness.