Phase Formation Features of Reactor Pressure Vessel Steels with Various Ni and Mn Content under Conditions of Neutron Irradiation at Increased Temperature

In this paper the phase formation and mechanical properties of VVER-type reactor pressure vessel (RPV) steels with various Ni (1.57–5.95 wt.%) Mn (0.03–0.76 content after neutron irradiation up to fluences in range (53–120) × 1022 n/m2 at 400 °C were studied. The possibility carbonitride under these conditions is shown. case sufficient (>1.5 (>0.3 Ni-Si-Mn precipitates observed. Their chemical composition close G-phase Γ2-phase differs from that radiation-induced VVER-1000 RPV steels. This indicates prerequisites for thermally conditioned mechanism growth enhanced by irradiation. It also shown optimized steel manufacturing technology coupled an ultralow (≤0.03 increased 5.26 wt.% facilitates suppressing carbonitrides formation. This, turn, reduces contribution hardening embrittlement and, correspondingly, high radiation resistance temperature (400 °C).