The Microstructure, Tensile and Impact Properties of Low-Activation Ferritic-Martensitic Steel EK-181 after High-Temperature Thermomechanical Treatment
Nadezhda Polekhina,
Valeria Linnik,
Igor Litovchenko,
Kseniya Almaeva,
Sergey Akkuzin,
Evgeny Moskvichev,
Vyacheslav Chernov,
Mariya Leontyeva-Smirnova,
Nikolay Degtyarev,
Kirill Moroz
Affiliations
Nadezhda Polekhina
Institute of Strength Physics and Materials Science SB RAS, 2/4 Pr. Akademicheskii, 634055 Tomsk, Russia
Valeria Linnik
Institute of Strength Physics and Materials Science SB RAS, 2/4 Pr. Akademicheskii, 634055 Tomsk, Russia
Igor Litovchenko
Institute of Strength Physics and Materials Science SB RAS, 2/4 Pr. Akademicheskii, 634055 Tomsk, Russia
Kseniya Almaeva
Institute of Strength Physics and Materials Science SB RAS, 2/4 Pr. Akademicheskii, 634055 Tomsk, Russia
Sergey Akkuzin
Institute of Strength Physics and Materials Science SB RAS, 2/4 Pr. Akademicheskii, 634055 Tomsk, Russia
Evgeny Moskvichev
Institute of Strength Physics and Materials Science SB RAS, 2/4 Pr. Akademicheskii, 634055 Tomsk, Russia
Vyacheslav Chernov
JSC “A. A. Bochvar High-Technology Research Institute of Inorganic Materials”, 5 Rogov St., 123060 Moscow, Russia
Mariya Leontyeva-Smirnova
JSC “A. A. Bochvar High-Technology Research Institute of Inorganic Materials”, 5 Rogov St., 123060 Moscow, Russia
Nikolay Degtyarev
JSC “A. A. Bochvar High-Technology Research Institute of Inorganic Materials”, 5 Rogov St., 123060 Moscow, Russia
Kirill Moroz
JSC “A. A. Bochvar High-Technology Research Institute of Inorganic Materials”, 5 Rogov St., 123060 Moscow, Russia
In this work, we study the effect of high-temperature thermomechanical treatment (HTMT) with deformation in the austenite region on the microstructure, tensile properties, impact toughness, and fracture features of advanced low-activation 12% chromium ferritic-martensitic reactor steel EK-181. HTMT more significantly modifies the steel structural-phase state than the traditional heat treatment (THT). As a result of HTMT, the hierarchically organized structure of steel is refined. The forming grains and subgrains are elongated in the rolling direction and flattened in the rolling plane (so-called pancake structure) and have a high density of dislocations pinned by stable nanosized particles of the MX type. This microstructure provides a simultaneous increase, relative to THT, in the yield strength and impact toughness of steel EK-181 and does not practically change its ductile-brittle transition temperature. The most important reasons for the increase in impact toughness are a decrease in the effective grain size of steel (martensite blocks and ferrite grains) and the appearance of a crack-arrester type delamination perpendicular to the main crack propagation direction. This causes branching of the main crack and an increase in the absorbed impact energy.
