New low alloy heat resistant ferritic steels T/P23 and T/P24 for power plant application

Higher efficiencies and increasing requirements for reduced emissions can only be met by fossil fired power plants through a further increase of steam temperature and pressure. Material development has mainly been focussed on high heat resistant martensitic 9–12% Cr steels. Ensuring higher steam parameters, however, has also lead to increasing requirements for tube steels in water walls, which can no longer be fulfilled with standard low alloy ferritic steels like 13CrMo4-4 (T12). The paper describes the properties of the newly developed steels T23 and T24. It also will be shown that they can have benefits by using them as P23/P24 for piping, especially for the refurbishment of old plants.