Exploratory Investigations of Low Charpy-V Upper Shelf Energy Steels with Irradiation.
NAVAL RESEARCH LAB WASHINGTON D C
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Steel plates and weld deposits exhibiting relatively low Charpy-V C sub v upper-shelf energy levels in the preirradiation condition are present in certain older reactor pressure vessels. Because the postirradiation notch ductility behavior of such materials is not well understood, a series of investigations has been undertaken for representative compositions. Forgings typical of older steel production are also being studied to develop specific trend information. This report describes exploratory investigations with a low upper-shelf A302-B plate, a companion weld heat-affected zone HAZ, a low upper-shelf A533-B weld and an A508-2 forging which exhibited a high C sub v energy correlation 135 J, 100 ft lb at the drop-weight nil-ductility transition NDT temperature. Standard C sub v and fatigue-precracked C sub v specimens were employed for notch ductility and dynamic fracture toughness K sub j determinations, respectively. The studies indicated 1 approximately equal radiation effects to longitudinal and transverse test orientations for the plate, 2 a significantly lower C sub v upper-shelf level for the HAZ compared to the parent plate, 3 greater radiation sensitivity by the HAZ compared to the parent plate as evidenced by transition-temperature elevation, 4 a postirradiation upper-shelf energy for the weld below the code index value of 68 J 50 ft.lb minimum, and 5 a trend in fracture toughness versus C sub v upper-shelf energy suggestive of a correspondence in these properties.
- Metallurgy and Metallography
- Fission Reactor Materials