Coalescence-Controlled Anisotropic Ductile Fracture

Abstract

The anisotropic ductile fracture of rolled plates containing elongated inclusions is promoted by both the dilational growth of voids and the coalescence process. In the present article, the emphasis is laid on the latter process. The effects of void shape and mainly of inter-particle spacings are investigated. Two types of coalescence models are compared: a localization-based model and plastic limit-load models. The capabilities of both approaches to incorporate shape change and spacing effects are discussed. These models are used to predict the fracture properties of two low alloy steels containing mainly manganese sulfide inclusions. Both materials are characterized in different loading directions. Microstructural data inferred from quantitative metallography are used to derive theoretical values of critical void volume fractions at incipient coalescence. These values are used in FE-calculations of axisymmetrically notched specimens with different notch radii and loading directions.