Compression Tests of Polycrystalline α-Iron up to High Strains Over a Large Range of Strain Rates

Overview & Synopsis

Compression tests have been performed on polycrystalline b.c.c. iron in order to study dynamic plasticity and evolution of microstructure. The paper describes the experimental setups and the results obtained at 295 K for strain rates 10-3s-1 ≤ dε/dt ≤ 104s-1 and plastic strains up to large values ε-0.8. Stress-strain diagrams have been found for all conditions mentioned. The rate dependence of stress indicates two regions of the rate sensitivity. The low strain rate range shows only slight rate sensitivity, but it increases rapidly at strain rates above 103s-1. This effect is accompanied by formation of twins. Optical and TEM micrographs confirm these observations. Dislocation density and micro-hardness have been also measured.