Characterization of ion irradiation effects on the microstructure, hardness, deformation and crack initiation behavior of austenitic stainless steel: heavy ions vs protons

Jyoti Gupta (1, 2) , Jérémy Hure (1) , Benoit Tanguy (1) , Lydia Laffont-Dantras (2) , Marie-Christine Lafont (2) , Eric Andrieu (2)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux

Irradiation Assisted Stress Corrosion Cracking (IASCC) is a complex phenomenon of degradation which can have a significant influence on maintenance time and cost of core internals of a Pressurized Water Reactor (PWR). Hence, it is an issue of concern, especially in the context of lifetime extension of PWRs. Proton irradiation is generally used as a representative alternative of neutron irradiation to improve the current understanding of the mechanisms involved in IASCC. This study assesses the possibility of using heavy ions irradiation to evaluate IASCC mechanisms by comparing the irradiation induced modifications (in microstructure and mechanical properties) and cracking susceptibility of SA 304 L after both type of irradiations: Fe irradiation at 450 °C and proton irradiation at 350 °C. Irradiation-induced defects are characterized and quantified along with nano-hardness measurements, showing a correlation between irradiation hardening and density of Frank loops that is well captured by Orowan's formula. Both irradiations (iron and proton) increase the susceptibility of SA 304 L to intergranular cracking on subjection to Constant Extension Rate Tensile tests (CERT) in simulated nominal PWR primary water environment at 340 °C. For these conditions, cracking susceptibility is found to be quantitatively similar for both irradiations, despite significant differences in hardening and degree of localization.

Mots clés: Austenitic SS; Irradiation effects; Microstructure

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Mécanique des matériaux [physics.class-ph]

Jyoti Gupta, Jérémy Hure, Benoit Tanguy, Lydia Laffont-Dantras, Marie-Christine Lafont, et al.. Characterization of ion irradiation effects on the microstructure, hardness, deformation and crack initiation behavior of austenitic stainless steel: heavy ions vs protons. Journal of Nuclear Materials, 2018, vol. 501, pp. 45-58. ⟨10.1016/j.jnucmat.2018.01.013⟩. ⟨hal-01780338⟩