Development of a mechanistic understanding of radiation embrittlement in reactor pressure vessel steels: Final report
The microstructures of a series of reactor pressure vessel (RPV) steels and model iron alloys with various Cu, Ni, and P contents were examined in unirradiated and neutron-irradiated conditions using high resolution analytical microscopy. Fractography techniques were also applied. Objectives were to isolate and identify the mechanisms by which these elements affect steel radiation embrittlement sensitivity as evidenced by notch ductility and tensile strength changes. Radiation hardening of a reference iron alloy was found associated with the formation of prismatic dislocation loops of an interstitial nature. A very low density of loops was observed for a low Cu-low P steel having a low radiation sensitivity. Copper decreased the size and increased number density of observable defects; however, the enhancement of radiation sensitivity by Cu is due to a radiation-induced formation of Cu-rich clusters/precipitates. No synergism between Cu and Ni was found in the model iron alloys except for an enrichment of the Cu clusters with Ni. Alloys containing appreciable P did not show intergranular fracture. The detrimental effect of this impurity on radiation sensitivity for the case of a low Cu content is due to a radiation-induced clustering of P. Phosphorus clustering was found absent in a high Cu-high P iron alloy, consistent with the apparent inactive role of P in radiation sensitivity of high Cu steels. The effect of alloying/impurity elements on the evolution of defect structures during irradiation is ascribed to vacancy trapping by solute atoms, leading to an increased number density of defects.
- Research Organization:
- Florida Univ., Gainesville (USA). Dept. of Materials Science and Engineering
- OSTI ID:
- 5689076
- Report Number(s):
- NUREG/CR-5063; MEA-2268; ON: TI88900296
- Country of Publication:
- United States
- Language:
- English
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36 MATERIALS SCIENCE
NUCLEAR POWER PLANTS
PRESSURE VESSELS
STEELS
EMBRITTLEMENT
PHYSICAL RADIATION EFFECTS
MICROSTRUCTURE
PROGRESS REPORT
REACTOR MATERIALS
ALLOYS
CONTAINERS
CRYSTAL STRUCTURE
DOCUMENT TYPES
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
NUCLEAR FACILITIES
POWER PLANTS
RADIATION EFFECTS
THERMAL POWER PLANTS
220200* - Nuclear Reactor Technology- Components & Accessories
360106 - Metals & Alloys- Radiation Effects