Improve creep properties of reduced activation steels by controlling precipitation behaviors

Effect of a new heat treatment and tantalum content on precipitation behaviors and mechanical properties of reduced activation was studied in this paper. The results indicated that the combined application of adding 0.26 wt.% tantalum content and the new heat treatment in the modified steel caused a decrease in the minimum creep rate of an order of magnitude and an increase in the rupture time of nearly an order of magnitude than the traditional reduced activation steel, because the former obtained a number of the finer MX and M23C6 carbides. The prior precipitation of MX by addition of tantalum or intermediate heat treatment that caused a decrease of the growth rate and mean size of M23C6 carbides. Both adding 0.26 wt.% tantalum content and intermediate heat treatment at 850 °C were proposed for an improvement of creep properties in reduced activation steels.