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Microstructural and microchemical characterization of nuclear pressure vessel welds

Thesis/Dissertation ·
OSTI ID:5681539
Quenched and tempered ASTM A533 Grade B steel is being widely used in the current construction of nuclear reactor pressure vessels. Studied on submerged arc A533 steel weldments show that the weld is more susceptible to irradiation embrittlement than either the base plate or the heat affected zone. Because of the complexity of the weld microstructure, few attempts have been made to correlate the microstructure with the mechanical properties on a sub-micron scale. In this investigation modern analytical electron microscopy (AEM) techniques were used to correlate the mechanical properties data of various welds with microstructural and microchemical studies. The A533 base plate material was characterized to discern those microstructural features that occur during welding. Microstructures and microchemistries in high and low copper content welds were compared in order to identify those microstructural features that may be responsible for the enhanced embrittlement seen in the high copper content weldment during irradiation. Results show that the A533 base plate steel resists softening even after 400 hours of tempering at 620/sup 0/C. This was attributed to precipitation of spherical copper particles and additional precipitation of acicular and spherical molybdenum carbides during tempering.
Research Organization:
Lehigh Univ., Bethlehem, PA (USA)
OSTI ID:
5681539
Country of Publication:
United States
Language:
English