Kinetics of the α-α′ phase separation in a 14%Cr oxide dispersion steel at intermediate temperatures

•14%Cr steel was studied after heat treatments at 400, 450 °C for 5000, 10,000hr.•α′ precipitates after 5,000 hr at 400 °C, while at 450 °C only after 10,000 hr.•Amount of α′ after 10,000 hr at 450 °C was larger, than after 10,000 hr at 400 °C.•Comparison of experimental results and calculations was performed.•It was concluded that in this steel separation occurs by the nucleation and growth.