Turbine components of high creep resistant MARBN steels for modern high efficient fossil-fired power plants

摘要

Sufficient energy availability in combination with lowest environmental pollution is a basic necessity for a high standard of living in each country. To guarantee this, power plants with improved technologies to achieve higher efficiency combined with reduced environmental impact are needed. The realization of this goal is not only a challenge for power station manufacturers, but also for manufacturers of special steels and forgings, which have to produce improved components with more advanced materials. B?hler Special Steel is a full package supplier of high quality components for modern highly efficient power plants. The presentation shows our research activities in open die forging and materials development of high mechanical and temperature loaded components for power generation applications and reports about our experiences in the fabrication of forged components for gas and steam turbines. The highly creep resistant 10% Cr-steels used for these components are designed for operating temperature up to 625°C and were developed in the frame of the European Cost research program. Requirements for these components are excellent mechanical properties and ultrasonic detectability results. Additionally our research activities on the latest generation of high temperature resistant steels for operating temperatures up to 650°C are shown – boron containing 9 % Cr martensitic steels (MARBN). Selected chemical compositions of MARBN steels were subjected to different heat treatments to produce an optimized microstructure. Creep exposure was investigated using optical microscopy, SEM and EBSD. Short term creep rupture tests at 650°C and 150 MPa were performed, followed by systematic microstructure investigations. From comparative creep test results, it can be concluded that advanced microstructures increase the time to rupture of the selected MARBN steels by more than 10 percent.