Building low-cycle fatigue curve to assess remaining lifetime of steel-teeming ladle turret

The tests were performed for low-cycle fatigue at the temperature of 90°C on the 15XCHД steel samples, which were taken from a lifting beam of CCM turret No.6 of PJSC Magnitogorsk Iron & Steel Works (MMK). The tests were performed using the Gleeble 3800 thermomechanical simulator in air atmosphere. The measurements of the sample deformations in the course of the testing were performed using a high-temperature detector of lateral deformations. According to the test results, fatigue curves were built for stress and deformation conditions, as well as a cycle curve of deformation. Regression equations were obtained for the low-cycle fatigue curve for stress and deformation conditions, as well as the regression equation for the cycle curve of deformation. It was demonstrated that the experimental values of stress and deformation conditions fit into the confidence interval of these equations with a probability of 99.5%, which allows using them for the assessment of the remaining lifetime of cyclically loaded structures of CCM ladle turret No.6. (paper)