Damage observation in a high-manganese austenitic TWIP steel by synchrotron radiation computed tomography

Internal damage below the fracture surface of a multiaxial specimen made of twinning-induced plasticity (TWIP) steel was observed by three-dimensional X-ray microtomography as very elongated 'primary' voids. Specific tools for the local damage analysis were developed. A gradient in void volume fraction was measured from the fracture surface down to the bulk of the scanned volume (from ∼0.06% to <0.02%). However, the fracture surface is mainly composed of tiny secondary dimples (>90% in area fraction), indicating strongly localized final fracture.