The yield behaviour of mild steel in dynamic compression

Results of earlier investigations of dynamic yield phenomena are reviewed. Experiments are described in which a mild steel specimen is subjected a to compressive impact load causing yield in 25 to 30μs. Stress-time curves are obtained and analyzed in terms of wave propagation, and a dynamic stress-strain relation is derived. Micrographs of specimens after dynamic yielding show that coarse slip does not occur, though there is some evidence of fine slip and grain boundary movement. Static compression tests on dynamically yielded specimens show that less hardening is caused by dynamic strain than by the same amount of static strain. The results are discussed in terms of dislocation theory.