High Temperature Alloys for Advanced Industrial Gas Turbines

Gas Turbines have found widespread use in industrial and marine applications for the provision of motive power and the generation of electricity. Their development has followed that of aero engines to a large extent but their scope has widened in a number of ways. Aero engines are designed with a more severe weight penalty than industrial gas turbines whereas the latter may have to use poorer quality fuels, are often subject to prolonged industrial and marine atmospheric corrosion and are expected to operate for periods in excess of 100 000 hours. The lower importance of power/weight ratio, in many applications, has enabled manufacturers to use cast iron and steel rather than titanium alloys for major components which has resulted in the unit cost of power to the customer being much less than that for aero engines. This paper provides an overview of requirements, selection, and future developments of materials for industrial gas turbines. In the first part, the basic types of industrial gas turbines are described, together with the efficiency requirements and design procedure and other factors which govern the selection of materials. Next, the property requirements are summarised and related to particular components, including casings, combustion chambers and exhaust systems, blades and discs. Future developments in industrial gas turbine design and materials and process development are evaluated. In the final part of the paper, opportunities for Materials Engineers at Universities, Research Institutions and Industry, Manufacturers of Material Product and The Institute of Materials are defined which will improve the reliability of gas turbine engines and reduce costs for the industry.