Influence of omnidirectional pressure on the development of porosity during necking under stretching of metals and alloys

The influence of omnidirectional pressure on microporosity developing in the neck of 45-μm-thick copper sheets tested for creep is considered. Comparing these data with a porosity measured in cylindrical specimens leads us to conclude that the transition from cleavage failure to shear fracture observed in copper under pressure is related to a decrease in the mean hydrostatic tension in the...