High-temperature mechanical properties and microstructure of 9Cr oxide dispersion strengthened steel compared with RAFMs

In this work, high-temperature mechanical properties and microstructure of a 9Cr-ODS steel were studied. The properties were compared with those of the current reduced activation ferritic/martensitic steels (RAFMs) of CLAM and JLF-1. The tensile strength of the 9Cr-ODS steel was almost twice the values of the RAFMs at all the test temperatures, and the strength level at 923–973 K was comparable to those of the RAFMs at 823 K. The 9Cr-ODS steel also exhibited superior creep strength. Prediction with Larson–Miller parameter for the typical blanket conditions suggested that the 9Cr-ODS steel can successfully extend the maximum operation temperature to ∼923–973 K. The 9Cr-ODS steel has a tempered martensitic structure with uniform oxide particles in the matrix. After creep tests, the mean diameter and density of the oxide particles did not change significantly by different creep temperatures and stresses, suggesting the stability of the microstructure.