Hardening and microstructural evolution in A533B steels under neutron irradiation and a direct comparison with electron irradiation

Current understanding of radiation-induced degradation in light water reactor structural materials

“…The root of the volume fraction determined by 3DAP analysis is proportional to the transition temperature shift and the increase in hardness or yield strength. This relationship is widely found in surveillance data [59,69,71], MTR irradiation data [77,79] and also various changed particle irradiation data [37], and is irrespective of the Cu content and irradiation conditions. Figure 8 shows an example of the linear relationship between the cluster volume fraction and transition temperature shift [59].…”

“…Gamma rays can cause displacement damage in materials through high-energy electrons and positrons that are produced through gamma-material interactions, Compton scattering, pair production and the photoelectric effect [35]. It was confirmed that electron irradiation with energies of several MeV causes hardening in low-alloy steels [36][37][38]. For thermal neutron effects, the contributions to displacement damage production and additional damage production through the nuclear reaction of boron were discussed.…”

“…The formation of Cu-rich clusters was detected at fluences of the order of 10 17 n/cm 2 by using the PA-CDB technique. Figure 6 shows an example of CDB spectra in 0.12%Cu A533B steel irradiated in a MTR at 290 • C, showing the rise of the Cu peak at 1 mdpa (∼5 × 10 17 n/cm 2 ) [37]. The coarsening of Cu-rich clusters (increase in size and decrease in density) is known to occur in high-Cu model alloys, and was also recently reported in surveillance specimens (0.3%Cu) at high fluences [53].…”

Effects of stress on radiation hardening and microstructural evolution in A533B steel

“…The yield strength at 290°C is 570 MPa. In the previous studies, it was confirmed that well-defined solute clusters and dislocation loops form in this material under neutron, electron, and heavy-ion irradiations in unstressed condition [15][16][17][18][19].…”

“…Although Ga atoms which were used in FIB micro-processing were also detected in these specimens of the elemental maps, the implanted Ga concentration was estimated as 0.1 at%, which was a negligibly low level. In order to obtain quantitative data on the cluster formation, elemental maps were analyzed based on the clustering of Si and Cu atoms which were recognized as the main elements constituting the core of solute clusters in the previous studies [15][16][17][18][19]. The clustering of Si atoms was most clearly observed in both specimens, and the clustering of Mn and Ni atoms was identified in the same position as the Si clustering.…”