Nickel-Base Alloys for Advanced Power Plant Components

The materials requirements for advanced steam power plant operating at steam temperatures of 700 oC are described and it is shown that several nickel-base alloys that were developed for gas turbine components are suitable candidate alloys. The materials testing programmes underway to qualify these alloys for steam power plant applications are summarised. The physical and mechanical properties of selected alloys (Alloys 230, 617, 263, 718Plus and 740) are discussed. For the alloys 617 and 740, modifications have been proposed to optimise performance at temperatures around 700 oC. The microstructural stability, steam oxidation resistance and fabrication issues in the production of large components are also considered.