Analysis of Fracture Mechanism of Cast Steel for Different States of Stress

In this paper a plastic deformation and a damage evolution in low-carbon cast steel containing non-metallic inclusions are analysed experimentally and numerically. Two microstructures of the cast steel have been obtained after appropriate heat treatment. Tensile tests of smooth specimens and axisymmetric notched specimens have been performed. The notched specimens have the notch radii: 1 mm, 3 mm and 7 mm. Fractography of the specimens was carried out to observe fracture mechanisms. The mechanism depended on the stress state in the notched specimens. The fractography showed the existence of two fracture mechanisms: ductile failure and by shear. The process of the voids growth formed on the non-metallic inclusions was the process which included in the explanation of the damage mechanism. Modelling of deformation of the specimens has been used with the model suggested by Gurson, Tvergaard and Needleman. The model is implemented in the Abaqus finite element program. The computer simulation was performed using ABAQUS system. The computed output was compared with the experimental results obtained for specimens of the same shape.