Structure and properties of nano-sized Eurofer 97 steel obtained by hydrostatic extrusion

The objective of the present work was to apply hydrostatic extrusion to Eurofer 97 steel – a fusion relevant material that can be used for structural application in ITER. Samples were hydrostatically extruded in a multi-step process with a total true strain of about 4. Microstructure observations via light and transmission electron microscopy revealed significant grain size refinement from about 400 nm to 90 nm and changes in carbide size and distribution. Microstructure changes resulted in substantial improvement in mechanical properties of the material (the ultimate tensile strength and yield stress increase from 691 MPa to 1769 MPa and 582 MPa to 1641 MPa, respectively) which were evaluated by hardness measurements and tensile tests.