Corrosion Behavior of Austenitic Steels 1.4970 (15-15 Cr Ni), 316L and
1.4571 (316-Ti) in Flowing Low-oxygen LBE with 10-7 mass % of Oxygen
at 400 to 550°C
Juergen Konysa, Valentyn Tsisarb, Carsten Schroerc
Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1,
76344 Eggenstein-Leopoldshafen, Germany
a
juergen.konys@kit.edu, bvalentyn.tsisar@kit.edu, ccarsten.schroer@kit.edu
Abstract
The world-wide development of Gen-IV nuclear reactors and accelerator driven systems (ADS) has
initiated interest in the evaluation of the compatibility of e.g., stainless steels with heavy liquid
metals (HLM). Pb and Pb-Bi eutectic (LBE) are foreseen to be utilized as a coolant and/or
spallation target while austenitic steels are considered as main candidates for vessel (316L),
structural components (316-Ti) and cladding (1.4970) materials.
Long-term corrosion behavior of austenitic steels 1.4571 (316-Ti), 1.4970 ( 1 5 - 1 5 C r N i )
and 316L was investigated in flowing l o w - oxygen LBE (2 m/s, 10-7 mass% O) at 400, 450
and 550 °C for up to 13,000 h, respectively. The corrosion modes and material losses were
analyzed qualitatively and quantitatively. Steels underwent both oxidation accompanied by
formation of thin (0.5 µm) Cr-based oxide films and selective leaching of Ni and Cr that
resulted in formation of a layer-type ferrite zone and deeper local damages with pit-type
appearance both penetrated by Bi and Pb. The corrosion loss increases with time and
temperature providing that the oxygen content is constant (10-7 mass%). Detailed
quantitative analyses of corrosion loss showed that at 400 °C, solution-based corrosion attack
in the view of rare and local pits is started to be observed after ~4,500 h, whereas at longer
durations, maximum depth of corrosion attack reached ~ 14, 23 and 57 µm on 1.4970, 316L and
1.4571, respectively At 550°C metal recession ranged from 23 to 60 mm after 2011 h that
correlates well with thickness of ferrite layer formed. The maximum depth of local attack
reached 587, 207 and 158 mm for 1.4571, 1.4970 and 316L steels, respectively. The effect
of composition, surface state and bulk micro-structure on the corrosion response of steels
is discussed. The results are compared with those obtained in LBE with higher oxygen
concentration, i.e., 10-6 mass% O.
Keywords: Lead-cooled reactors, austenitic steels, oxygen-control, selective leaching.