Evaluation of Ductile Fracture of Structural Steels by Microvoid Model

Abstract

In the present work, the ductile fracture of structural steels and the effect of plastic pre-strain on ductility have been investigated by tensile test. The fracture process consisting of void nucleation, growth and coalescence was observed by scanning electron microscopy (SEM). The nucleation strain of microvoid was measured experimentally. The critical interfacial strength of particle/matrix interface was calculated by dislocation model and continuum analysis, and the void growth was evaluated by Rice-Tracey model. It was found that longitudinal void coalescence does not affect fracture even though large cracks exist, but particle position affects void nucleation. Thomason's plastic limit-load model was used to predict void growth strain. Through the analysis of ductile fracture process, the influence of plastic pre-strain on ductility was discussed.