For environmental reasons it is necessary to increase the process temperature in power plants and in industry, e.g. in chemical plants. This implies the development of steels and alloys that can be used at high temperatures and severe conditions. These materials need to be capable of enduring long-term use. On the other hand, equipment and plants built in the 1970s have become aged and their control requires a high degree of accuracy to ensure their safe operation. In this case, the most important property of the materials is creep, especially long-term creep, and thus it is necessary to...