Effect of hot cross rolling on the microstructure and mechanical properties of an Fe-14Cr ODS ferritic steel

Oxide dispersion strengthened (ODS) reduced activation ferritic steels are leading candidates to become part of the structure of the first wall/blanket of future fusion reactors. Their major drawback is their poor toughness, which must be improved. In this work, an ODS ferritic steel having nominal composition Fe-14Cr-2W-0.2Ti-0.55 Fe2Y (wt%), produced by mechanical alloying of prealloyed powders with Fe2Y intermetallic particles and consolidated by hot isostatic pressing, was subjected to either thermal treatments at high temperature or hot cross rolling in an attempt to investigate the effectiveness of such post-consolidation thermomechanical treatments. Its microstructure, nanoparticle dispersion and mechanical properties were analysed and correlated on each condition. As compared with the annealing treatments hot cross rolling led to a significant decrease in the grain size as well as a slight decrease in the size of some of the secondary phases present in the material. Also, the impact and tensile behaviour was improved over the whole temperature range studied.