Ductile failure in polycrystalline OFHC copper

Ductile failure in polycrystalline oxygen-free, high-conductivity copper is explored through uniaxial tension experiments. Specimens obtained through tests interrupted at various stages of deformation and failure evolution are examined through quantitative microscopy to discern the mechanisms of failure and the local strain evolution. The formation of a single rectangular prismatic channel-like cavity, and its subsequent growth as a rectangular cavity, are demonstrated. Fractographic observations are used to suggest that self-similar expansion of the cavity is through an alternating slip mechanism. Local strain levels are estimated from measurements of the change in grain size with deformation and used to indicate that the local values of failure strains are likely to be much larger than that estimated from strains averaged over characteristic specimen dimensions such as the gage length or the specimen diameter.