Temperature dependence of irradiation hardening due to dislocation loops and precipitates in RPV steels and model alloys

Abstract

A relative contribution to irradiation hardening caused by dislocation loops and solute-rich precipitates is established for RPV steels of WWER-440 and WWER-1000 reactors, based on TEM measurements and mechanical testing at reactor operating temperature of 563 K. The pinning strength factors evaluated for loops and precipitates are shown to be much lower than those obtained for model alloys based on the room temperature testing as well as those evaluated by means of atomistic simulations in the temperature range of 300 to 600 K. This discrepancy is explained in the framework of a model of thermally activated dislocation motion, which takes into account the difference in temperature and strain rate employed in atomistic simulations and in mechanical testing.

Crystal plasticity modeling of irradiation effects on flow stress in pure-iron and iron-copper alloys

“…The form of Eq.14 ensures that the loops are not annihilated by mobile dislocations whose slip planes coincides with the habit planes of the loop. The resistance of vacancy and copper clusters to dislocation motion is incorporated following [27] as…”

“…The influence of irradiation induced defect on the increase of yield stress is typically modeled using the Orowan's strengthening model ∆σ = αMGb √ Nd (16) where α is the strength factor that depends on the defect type and size [27,34], and, M is the Taylor factor. Eq.16 has been used in [15] to quantify the contribution of the different defect types such as clusters, precipitates and loops on the overall increase of yield-strength for a RPV steel and its model alloys irradiated to 0.1 dpa.…”

Proton Irradiation Effects on Hardness and the Volta Potential of Welding 308L Duplex Stainless Steel

“…At present, various studies of irradiation hardening have been conducted using austenite stainless steels (face-centered cubic, fcc), such as 304L and 316L, which are widely used as nuclear structural materials [10,11,12]. In addition, other nuclear materials, including oxide dispersion strengthened steels (body-centered cubic, bcc) [13,14], vanadium alloys [15], high-entropy alloys and reactor pressure vessels (RPV) steels have also been studied [16,17,18,19,20]. Many factors, which affect irradiation hardness have been considered, including irradiation dose, temperature, and defect types.…”

The effects of oxide evolution on mechanical properties in proton- and neutron-irradiated Fe-9%Cr ODS steel

“…To attain samplespecific α i values, some studies have calculated the relative obstacle strengths necessary to mathematically relate the microstructure to the measured mechanical behavior (via indentation or tensile testing techniques) [19][20][21]. Adding to the complexity, additional studies have suggested that the strength of each obstacle is also dependent upon the size and/or number density of the obstacles in the matrix of the material [10,[22][23][24]. All of these approaches have provided valuable insight into how dislocations interact with different types of obstacles.…”