Creep properties and microstructural evolution of austenitic TEMPALOY steels

The steam parameters in the new high efficiency fossil fuel power plants are continuously increasing, requiring new advanced materials with enhanced creep strength able to operate on the most severe temperature and pressure conditions. For super-heater and re-heater applications, TEMPALOY AA-1 steel, an evolution of 18Cr10NiNbTi alloy, has been developed through the addition of 3%Cu and B, significantly enhancing the creep resistance, while offering typical corrosion properties of 18%Cr steels. This paper describes Tenaris’ tubular products in the field of austenitic grades for applications in Ultra Super Critical power plants: the production route and the main microstructural and mechanical properties of TEMPALOY AA-1 and TEMPALOY A-3 steels, including the effect of shot blasting on steam-oxidation resistance, their creep–rupture properties and their microstructural evolution during temperature exposure are presented.