Effect of Internal Pressure on Microstructural and Mechanical Properties of X10CrNiCuNb18-9-3 (SUPER 304H) Austenitic Stainless Steel

Despite the current tendencies towards decarbonization of the energy sector, it is still necessary to maintain the lifetime of existing coal-fired power plants. Austenitic stainless steels belong among materials used in energetics, in this case, SUPER 304H (X10CrNiCuNb18-9-3). This steel is used for the experiment that simulates real operating conditions, specifically high temperature (700°C) and constant inner pressure (25 MPa), which is induced by inserting a distilled water medium before sealing. This work deals with the evaluation of the microstructure and mechanical properties of the SUPER 304H specimens, both with and without inner pressure. All the specimens underwent the same long-term exposure in a form of laboratory annealing. The mechanical properties were evaluated by performing the tensile, impact and hardness tests and microstructure was characterized by light optical microscopy and scanning electron microscopy.