THE EFFECT OF RESIDUAL ELEMENTS ON 550F IRRADIATION RESPONSE OF SELECTED PRESSURE VESSEL STEELS AND WELDMENTS.
NAVAL RESEARCH LAB WASHINGTON D C
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The effect of variable residual element contents on 550F radiation embrittlement sensitivity of pressure vessel steels was examined. Results indicate that phosphorus and copper can contribute significantly to the 550F radiation embrittlement sensitivity of Type A302-B steel. The results also show that vanadium may have a slight adverse effect and that sulfur is neutral, although it serves to decrease the full shear energy absorption level of the steel. Nitrogen variations from approximately equal to 0.008 to 0.015 in aluminum deoxidized steel have no significant effect, while the addition of aluminum to Ni-Cr-Mo steel with a given nitrogen content may slightly promote irradiation embrittlement. The program results demonstrate that apparent insensitivity to 550F irradiation embrittlement can be consistently achieved with laboratory heats of a nominal A302-B steel composition by maintaining the total residual element contents at a low level. Radiation embrittlement sensitivity of weldments was investigated in a program aimed at the development of low sensitivity weld fillers for joining Ni-Cr-Mo steel. Data from this new program again point to copper as a dominating factor in determining radiation embrittlement sensitivity, further verifying the results obtained in the NRL-USS A302-B steel investigation. Two experimental weld wire compositions with low copper contents 0.1 are shown to possess resistance to 550F irradiation embrittlement equal or superior to that of A543 base plate. Author
- Metallurgy and Metallography
- Couplers, Fasteners and Joints
- Fission Reactor Materials