Failure surfaces morphology for specimens with stress concentrators using scanning electron microscopy

Materials develop different type of behaviours based on environmental conditions, loading conditions and different processing methods. Following up a previous work, the authors noticed that a mainly ductile material had features of brittle failure when the material was used for specimens with stress concentrators. Three types of specimens with stress concentrators were chosen and tests were carried out in order to develop a triaxial state of stress using a universal testing machine. After the failure, new specimens of the failure surface were debited and they were studied using SEM analysis. Elements of both brittle and ductile failures were identified and the study went further to verify the chemical composition of the material and the presence of impurities, if any. The authors concluded that the processing methods, the chemical composition and contamination of the material greatly influences the behaviour and type of failure of the specimens. (paper)