Abstract
Powder metallurgy (PM) SUS304 stainless steels consolidated by hot extrusion process with different oxygen contents from about 100 to 250 ppm were investigated in terms of creep properties at elevated temperatures with a comparison of the cast and wrought (CW) material. PM materials show the same level of creep rupture strength as CW material at 650°C, but lower values with increasing temperature to 950°C. This lower creep rupture strength of PM materials is partly due to fine grains resulting from the suppression of grain growth by the dispersion of oxides originated from powder surfaces. With increasing oxygen content, the creep rupture strength and ductility of PM materials are decreased by cavity formation promoted by oxides situated at the grain boundaries.
