Microstructural characterization of the ODS Eurofer 97 EU-batch

Abstract Four as-processed forms (Plate 16, Plate 6, Rod 20 and Rod 12.5) of the ODS Eurofer 97 EU-batch produced under different thermomechanical conditions have been investigated by scanning nuclear microprobe, scanning and transmission electron microscopy, energy dispersive X-ray spectroscopy, electron backscattered diffraction, high-temperature X-ray diffraction and microhardness measurements. The materials presented a ferritic microstructure with a homogeneous distribution of Y. The thicker plate (Plate 16) presented a fine carbide dispersion while the other forms (Plate 6, Rods 20 and 12.5) showed carbide morphologies corresponding to pseudo-pearlitic and pseudo-bainitic transformations with matching hardness values. Hot rolling induced crystallographic textures of the {1 0 1} 〈 1 0 1 ¯ 〉 type (Plates 16 and 6), rotary swaging resulted in a complex texture (Rod 20) and extrusion produced a strong 〈1 0 1〉 fiber texture (Rod 12.5). X-ray diffraction experiments showed that at a cooling rate of 5 °C/min the complete austenite-to-ferrite transformation occurs between 760 and 750 °C compromising the material quenchability.