Properties and experience with a new austenitic stainless steel (TEMPALOY AA-1) for boiler tube application

A new austenitic stainless steel (TEMPALOY AA-1:0.1C-18Cr-10Ni-3Cu-Ti-Nb) has been developed. The allowable tensile stress of this steel is more than 30% higher compared with that of ASME SA-213 Grade TP347H in the temperature range 600-700 C. This superior creep rupture strength is caused by the precipitation of MC and M{sub 23}C{sub 6} carbides, and Cu-rich phase. The hot corrosion resistance and long term aging properties of this steel are at the same level as 18Cr-8Ni stainless steels. The steam oxidation resistance can be achieved by a shot-blasting method. Two years practical service as the superheater tubes in a boiler has revealed that the mechanical properties and environmental resistance of this steel are sufficient as boiler material. This steel has been already approved by METI standard in Japan as METI SUS321J2HTB. (orig.)