Abstract
Both of the newly developed tungsten strengthened ferritic steels considered here, i.e., 2.25Cr-1.6W-V-Nb(HCM2S) steel and 12Cr-0.4Mo-2W-1Cu-V-Nb(HCM12A) steel, have the practical capability to be used for steam enerator tubing due to their excellent fabricability and very high creep strength. These steels have already been approved by the ASME Boiler and Pressure Vessel Code Committee for use in Section I construction. A field service test putting these steel tubes in service along with comparative materials in the tertiary superheater and secondary reheater of a 156 MW utility power boiler has been conducted since April 1993, and the tubes were removed to confirm their material properties and corrosion / steam oxidation behaviors after one-year and 3-year periods of service. The investigation results showed that the practical performances of HCM2S and HCM12A steel tubes were good, demonstrating superior corrosion resistance and less material degradation than the comparative materials. This paper deals with the practical properties and examination results of these newly developed steels compared with conventional boiler steels.
