Damage evolution in 1018 steel and 1100 aluminum

Damage evolution is investigated in a 1018 hot extruded ingot and an 1100-H18 aluminum extruded rod. Using a specimen geometry first developed by Bridgman, notched tensile specimens were used to investigate the influence on the hydrostatic stress on failure. Using an analysis technique from Nash and Cuius, the diametral strain to failure and hydrostatic stress were used to generate the so-called Hancock-Mackenzie plot. For both alloys investigated, the plots displayed an exponential decay in the strain to failure with increasing hydrostatic stress. Six to ten specimens of each geometry were tested; therefore, the data in the Hancock-Mackenzie plot gives a visual representation of the material and experimental variability associated with the Bridgman type specimens.