Void Growth in Plastically Deformed Free-Cutting Brass

The void growth occurring during tensile testing of uniaxial and notched specimens of free-cutting brass has been determined experimentally. This material contains a globular lead phase which tears or bursts to nucleate voids during deformation. Using quantitative metallographic data from specimens whose deformation was interrupted prior to failure, histories of void volume fraction and void aspect ratio were determined. The measured stress-strain response from the tensile tests was shown to be close to predictions from a finite element model incorporating Gurson’s constitutive model for a porous plastic solid. Predicted void growth rates agreed well with experiment for uniaxial specimens but were less than the measured growth rates in notched, high triaxiality specimens.