Generation of allowable stress for indigenously developed 304HCu Stainless steel

Abstract

The 304HCu stainless steel (SS) is the candidate material for reheater and superheater tubes in Advanced Ultra Supercritical (AUSC) coal-fired power plants of India. In the present study, the creep design data have been generated for indigenously developed 304HCu SS using the creep properties (creep strain and the rupture life) and tensile properties available at the temperatures 923 K, 973 K and 1023 K. The time dependent allowable stresses were obtained for the above steel according to the stress criteria specified in ASME Section III Division 5 Subsection HB. The allowable stresses were also derived in the creep as well as non-creep regimes as per the guidelines in ASME Section IID. In both the cases, the maximum allowable stress at each temperature was dictated by the stress to cause rupture. The allowable stress determined as per Section IID was the same as that estimated according to section III.5 HB for creep exposure of 100,000 h. Further, it must be mentioned that, at the temperature range 923–1023 K, the indigenously developed 304HCu SS possess allowable stresses that are in par with the corresponding values specified in ASME code case 2328–2.