ABOUT CHARACTERISTIC TENSILE DEGRADATION STRESSES OF STRUCTURAL MATERIALS

The stages of fracture of the structural steels 12Cr18Ni10T and F500W in tension are considered. The shape of the deformation diagrams has been analysed and characteristic stresses of material degradation, which characterise the stages of damage development, have been identified. On the basis of the analysis of the strain dependence of the second derivative of stress on strain on the load curve, a new characteristic point of degradation σ has been singled out. During the stretching of the specimens, the zones of plastic deformation were evaluated by means of digital image correlation (DIC), acoustic emission (AE) parameters and material damage characteristics. It is shown that after the stress σ is reached, a highly deformed plastic zone is formed, the damage increases and the acoustic emission characteristics change. The correlation between the estimated parameters and the stage of fracture development has been established.