Influence of structural-phase state of ferritic-martensitic steels on the helium porosity development

10th International School-Conference on Materials for Extreme Environment: Development, Production and Application

Chernov, I.I.^1 ; Staltsov, M.S.^1 ; Kalin, B.A.^1 ; Bogachev, I.A.^1 ; Guseva, L Yu^1 ; Dzhumaev, P.S.^1 ; Emelyanova, O.V.^1 ; Drozhzhina, M.V.^1 ; Manukovsky, K.V.^1 ; Nikolaeva, I.D.^1

National Research Nuclear University MEPhI, Moscow Engineering Physics Institute, Kashirskoe highway, 31, Moscow

115409, Russia^1

关键词: Ferrite grains;    Ferritic-martensitic steels;    Helium porosity;    Intensive plastic deformation;    Irradiation temperature;    Microcrystalline structures;    Structural-phase state;    Water quenching;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/130/1/012004/pdf
DOI  :  10.1088/1757-899X/130/1/012004

来源: IOP

【 摘 要 】

Transmission electron microscopy (TEM) has been used to study the effect of the initial structural-phase state (SPhS) of ferritic-martensitic steels EK-181, EP-450 and EP-450- ODS (with 0.5 wt.% nanoparticles of Y2O3) on the of helium porosity formation and gas swelling. Different SPhS of steel EK-181 was produced by water quenching, annealing, normalizing plus tempered, intensive plastic deformation by torsion (HPDT). Irradiation was carried out by He+-40 keV ions at 923 K up to fluence of 5-1020He+/m2. It is shown that the water quenching causes the formation of uniformly distributed small bubbles (d ∼ 2 nm) of the highest density (ρ∼ 1025m-3). After normalization followed by tempering as well as after annealing bubbles distribution is highly non-uniform both by volume and in size. Very large faceted bubbles (pre-equilibrium gas-filled voids) are formed in ferrite grains resulting in high level of gas swelling of the irradiated layer with S = 4,9 ± 1,2 and 3.8 ± 0.9% respectively. Nano- and microcrystalline structure created by HPDT completely degenerate at irradiation temperature and ion irradiation formed bubbles of the same parameters as in the annealed steel. Bubbles formed in EP-450-ODS steel are smaller in size and density, which led to a decrease of helium swelling by 4 times (S = 0.8 ± 0.2%) as compared to the swelling of the matrix steel EP-450 (S = 3.1 ± 0.7%).