This chapter gives an overview of the R&D program done in Europe during the last 40 years for the development of heat-resistant high-temperature 9?12% chromium steels for the USC development and superalloys for the development of A-USC power plants. In the development of 9?12% chromium, the steel have shown excellent results with respect to materials for heavy section boiler components and steam lines such as P92 and for turbine rotor and casing such as alloys FB2 and CB2. These alloys are the backbone for all present and coming USC plants operating at around 600°C. The R&D activities are also contributed with a fundamental understanding of the behaviour of the 10?12% Cr steels after long-time exposure as well as an explanation of the drop in creep rupture strength when operation at temperatures above 600°C. For the development of superalloys for A-USC power plant aiming steam parameters around 700°C, the EU Community established the first huge R&D project Thermie AD700 approaching the 700°C technology. This project focused on advanced 12% chromium pipe steels, high-performance austenitic tube steels, and advanced nickel-based alloys for the hot end of such a boiler and turbine construction as candidate material for an A-USC power plant. Only the advanced austenitic tube material Sanicro 25 fulfilled all requirements for being used as a full-qualified material. All the other development activities demonstrated interesting and encouraging results but did not fulfill all requirements for a basic qualification. Relevant and very useful basic knowledge and knowhow for the investigated steels and super alloys have been obtained as well as good technological result in manufacturing of large scale components, tubes, pipes, cast and forged, as well as, for the welding technologies. At present, no project for the construction of an A-USC demonstration plant in Europe is foreseen due to the very high investment cost and the restrictions regarding CO2 emission. If the development of the A-USC technology could be realised, countries such as India and China will have the best changes for a successful implementation.

» Author: O. Bar-Yosef

» Reference: Materials for Ultra-Supercritical and Advanced Ultra-supercritical Power Plants

» Source: ScienceDirect - GPP

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