Mechanical behavior and damage kinetics in nodular cast iron: part II. Hardening and damage

The present article examines the tensile behavior of nodular cast iron (NCI ) and distinguishes the different parts of the hardening mechanisms and dam age processes. In regard to hardening, particular interest is given to the evolution of the effective-stress (Sigma (ef)) and back-stress (X) componen ts. In particular, the high value of the back stress is explained in terms of different heterogeneity levels. The influence of damage on these two str ess components is studied. It is established that damage softens the effect ive stress and slightly hardens the back stress. Finally, using a modified Gurson-Tvergaard potential that takes into account the kind of hardening, t he mechanical behavior (hardening and damage) of the NCI is modeled. The in fluence of damage on the effective stress is well described.