EUROFER 97 steel is a candidate structural material for the future fusion reactors and Test Blanket Modules (TBMs). In the present work microstructure of Eurofer 97 was modified by hydrostatic extrusion in multi-step process with total true strain exceeding 3.
TEM observations showed that HE causes significant grain refinement from about 400 to 80 nm. This is accompanied by improvement of the tensile mechanical properties and microhardness. On the other hand, there is a clear decrease in the resistance to brittle fracture as measured in the Charpy impact tests.
In order to improve strength/ductility/fracture toughness balance, the extruded samples were annealed for 1 hour at temperature range of 473-1073K. The results obtained for samples after post-extrusion annealing are discussed in terms of the microstructure (grain size, precipitation, dislocations) relationship to the properties of Eurofer steel.