Dynamic deformation behavior of ultrafine-grained low-carbon steels fabricated by equal-channel angular pressing

摘要: The dynamic deformation behavior of ultrafine-grained low-carbon steels fabricated by equal-channel angular pressing (ECAP) was investigated in this study. Dynamic torsional tests, using a Kolsky bar, were conducted on four steel specimens, two which annealed at 480 °C after ECAP, and then the test data compared terms microstructures, tensile properties, adiabatic shear-band formation. pressed specimen consisted very fine, equiaxed grains 0.2 to 0.3 µm size, slightly coarsened annealing. results indicated that maximum shear stress decreased with increasing annealing time, whereas fracture strain increased. Some bands observed gage center dynamically deformed specimen. Their width smaller than 1-hour-annealed specimen, but they not found 24-hour-annealed Ultrafine, 0.05 size formed inside band, their boundaries had characteristics high-angle grain boundaries. These phenomena explained recrystallization due highly localized plastic temperature rise during deformation.