THE EFFECT OF MICROSTRUCTURE ON THE MECHANICAL-PROPERTIES AND ADIABATIC SHEAR-BAND FORMATION IN A MEDIUM-CARBON STEEL

Using a torsional split-Hopkinson bar, high strain rate tests in the o rder of 1000 s(-1) were conducted on 5 different heat treatments of a medium carbon steel. The heat treatments were; as received, fully anne aled and air cooled and quench tempered at 315, 480 and 650 degrees C, each for 1 hour. The microstructures obtained were coarse pearlite, u nresolved pearlite in a ferrite matrix and three different tempers of martensite. It was found that ferrite in the microstructures would alw ays deform preferentially over any other phase present in the material . In addition, if the ferrite was uniformly distributed, the ASB would be uniformly deformed. However, when it was segregated, granular type shear band surfaces would be observed.