Ductile fracture of duplex stainless steel with casting defects

Experimental and numerical studies were carried out on CF8M steel with special regard to the influence of casting defects i.e. shrinkage cavities on fracture behaviour. As-received and thermally aged materials were studied. Physical steps of damage in specimens containing casting defects were observed using in-situ tensile tests in a scanning electron microscope. Mechanical properties of duplex stainless steel were characterised using three-point bend tests of three types of specimens — defect free, pre-cracked, and containing shrinkage cavities. These mechanical tests were simulated using Gurson's model including crack nucleation. A modelling of the shrinkage cavities is proposed in order to study their influence on the mechanical response of the specimen.