The European efforts in development of new high temperature rotor materials - COST536

Abstract

Despite the ongoing efforts to increase the amount of available alternative energy sources, fossil fuels such as lignite and hard coal will remain important for the energy mix and sustainability of energy supply. Fossil-fuelled Steam Power Plants (SSP's) or Combined Cycle power plants (CCPP's) will also continue to supply a significant portion of our energy needs. Within the frame of European COST536, a new project was installed with the aim of Alloy development for Critical Components of Environmentally friendly Power planTs (ACCEPT) aiming for material solutions for steam conditions up to 650 C. Martensitic materials should be used for thick-walled components to maintain high operational flexibility of such large plants. Rotors, casings, bolts, tubes, pipes, and water walls, are the critical components under current investigation. The class of the 9-12%Cr steels offers the highest potential to meet the required property levels for critical components such as rotor forgings. Therefore a significant effort to increase the application temperature of these steels was and is the focus of studies within Europe. Although there are 600 C materials already being successfully utilised in a number of advanced European power plants, further improvement in creep strength is being achieved by the addition of Boron and a well balanced Co content. Full-size prototype components are now being tested. New ideas to improve the behaviour and increase the application temperatures are under investigation. Results are reported here. (orig.)