Influence of Long-Term Impact of Elevated Temperature on the Physical Properties of the Sanicro 25 Steel

The X7NiCrWCuCoNbNB25-23-3-3-2 (Sanicro 25) austenitic stainless steel is one of the newest and most promising steels for applications in ultra-supercritical and super-ultra-supercritical power units.In this work, the results of tests on microstructure changes and mechanical properties of Sanicro 25 steel after long-term ageing up to 20,000 h at 700 • C are presented.Investigation of the microstructure was performed using scanning electron microscopy and transmission electron microscopy.The identification of secondary phases was carried out by X-ray phase composition.Prolonged exposure to elevated temperature causes a change in strength properties due to the precipitation of secondary phases.The effect of ageing time at 700 • C on yield strength, tensile strength, and elongation determined at room temperature is shown.