Abstract
The microstructure of the oxide dispersion strengthened ferritic steel PM2000 has been investigated after compression by dynamic plastic deformation to a strain of 2.1 and after subsequent annealing at 715 °C. Nanoscale lamellae, exhibiting a strong 〈100〉 + 〈111〉 duplex fibre texture, form during dynamic plastic deformation. Different boundary spacings and different stored energy densities for regions belonging to either of the two fibre texture components result in a quite heterogeneous deformation microstructure. Upon annealing, preferential recovery and preferential nucleation of recrystallization are found in the 〈111〉- oriented lamellae, which had a higher stored energy density in the as-deformed condition. In the course of recrystallization, the initial duplex fibre texture is replaced by a strong 〈111〉 fibre recrystallization texture.
Highlights
Oxide dispersion strengthened (ODS) steels are considered to be promising structural materials for the next-generation fission and fusion reactors because of their excellent resistance to both irradiation damage and high-temperature creep [1,2]
The microstructure of the oxide dispersion strengthened ferritic steel PM2000 has been investigated after compression by dynamic plastic deformation to a strain of 2.1 and after subsequent annealing at 715 oC
3. Results The orientation map obtained by electron backscatter diffraction (EBSD) from PM2000 after dynamic plastic deformation (DPD) to a strain of 2.1 shows a nanoscale deformation structure with lamellar boundaries almost perpendicular to the compression axis (CA)
Summary
Oxide dispersion strengthened (ODS) steels are considered to be promising structural materials for the next-generation fission and fusion reactors because of their excellent resistance to both irradiation damage and high-temperature creep [1,2]. One way to refine the microstructure is via plastic deformation when original grains are subdivided by deformation-induced dislocation boundaries [5]. In previous studies [6,7], dynamic plastic deformation (DPD) at high strain rates (102˗103 s-1) [8] has been demonstrated to be more efficient in refining the microstructure of a ferritic/martensitic steel than deformation at low strain rates. The microstructure and the texture of a ferritic ODS steel PM2000 are investigated after DPD to a strain of 2.1. As the service temperatures of ODS steels in reactors are expected to be rather high, the thermal stability of the microstructure obtained by DPD is analysed focusing on orientation-dependent recovery and recrystallization taking place during annealing
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