Influence of inclusions on matrix deformation and fracture behavior based on Gurson–Tvergaard–Needleman damage model

Abstract

It is well known that the adverse effects of inclusions on the performance of a substrate are not negligible. Currently, as the level of smelting improves, the inclusion content in molten steel has been greatly reduced, but a completely pure material cannot be obtained still. Therefore, it is necessary to study the influence of inclusions on the steel matrix. In this study, the required parameters in the Gurson–Tvergaard–Needleman (GTM) damage model were accurately determined via in-situ tensile tests, and then, the parameters were substituted into the Abaqus model to simulate the tensile forming limit of the strip specimen. The final simulation results were in good agreement with the experimental results. On this basis, the effects of the number and distribution of inclusions on the mechanical properties of matrix materials are further analyzed. In this study, the in-situ tensile test method plays an extremely important role. Specifically, it can reveal the metallographic structure of samples under multiple load nodes during a single tensile experiment, which is conducive to determining parameters f0 and fF of the GTN model and the subsequent research results. The number and rate of pore growth were found to increase with the increasing number of inclusions. Moreover, the probability of pore polymerization increased, leading to damage and fracture of the specimen. Uneven distribution of inclusions resulted in uneven distributions of stress and strain during the deformation process, which changed the fracture behavior of the material. The first failed element appeared in the area with high inclusion content and extended to adjacent areas with high inclusion contents. The strength and plasticity of the material worsen with increasing difference in the distribution of inclusions.