Regularities of the deformed microstructure of ferritic-martensitic steel EP-823 after high-temperature thermomechanical treatment

The features of the microstructure of 12% chromium ferritic-martensitic steel EP-823 near the neck region of samples deformed by tension at T=-70, -40 °C, 20 °C and in the temperature range close to the reactor core operating temperatures of T = 650, 720 °C after high-temperature thermomechanical treatment (HTMT) are investigated. It is shown that at negative and room temperatures plastic deformation leads to curvature and fragmentation of martensitic lamellae, formation of new low-angle boundaries and a significant increase in the dislocations density. Deformation at high temperature contributes to the dynamic recovery, dynamic polygonization and increased sizes of carbide and carbonitride particles (M₂₃C₆ and MX type). (paper)