In collaboration with different industrial actors within the European Thermie-project, a new
austenitic stainless steel has been developed for use in advanced coal fired power boilers.
The grade is designed for high creep- and oxidation resistance, high structural stability and
good fabricability. It can be utilized at temperatures up to around 700°C. The temperature
strength is reached by precipitate strengthening through precipitation of fine Nb(C,N), NbCrN,
M23C6 and Cu-rich precipitates.
The so far obtained test results indicate that this grade has high oxidation resistance and
higher mechanical properties than other known austenitic stainless steels. This paper presents
the properties and results from manufacturing and testing during the development and
verification of data for the new grade. Also, some results from test installations in coal fired
boilers are presented.
Code cases as per The American Society of Mechanical Engineers Boiler and Pressure Vessel
Code, Section I and Section VIII, are filed for.
Key Words: Austenitic stainless steel, Boiler, Superheater, Tube, Creep, Oxidation, Hot
corrosion