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U.S. Department of Energy
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Proton induced swelling in Type 316 stainless steel

Technical Report ·
DOI:https://doi.org/10.2172/7107907· OSTI ID:7107907

Annealed Type 316 stainless steel was irradiated by 140-keV protons at 625/sup 0/C in vacuum (approximately 1 x 10/sup -8/ Torr) to study its swelling behavior. The maximum fluence used in the investigation, 2 x 10/sup 20/ protons/cm/sup 2/, created a peak damage of 590 dpa (displacements per atom) based on 25 eV as the displacement threshold. The swellings integrated along the entire proton range were obtained from the measurements of the step-heights at the junction of the irradiated and unirradiated regions. The swelling--dpa relationship was ascertained from the integrated swellings measured at various doses and the corresponding depth--dpa profiles. There were three stages in the swelling regime. The rate of swelling in stage I (dpa less than 200) increased continuously up to 0.8 percent per dpa. In stage II (425 greater than dpa greater than 200) the rate of swelling remained at its highest (0.8 percent per dpa). Rapid reductions in the rate began to occur beyond 425 dpa, and the swelling saturated at about 260 percent at 500 dpa. The values of swelling at 200 dpa and 425 dpa were 46 percent and 226 percent, respectively. The entire swelling regime could be explained by assuming reasonable changes in the dislocation density and void density as the void volume increases. To fit the experimental results it was necessary to assume that dislocations lying within a spherical shell of thickness 150 A around the voids did not contribute to void growth because of the effects of pipe diffusion, and that the dislocation's capture cross-section for interstitials was 4.2 percent higher than that for vacancies when the assumed displacement threshold (E/sub d/) was 25 eV or, alternatively, 7.5 percent higher if E/sub d/ was taken as 40 eV. The reduction in the rate of swelling due to pipe diffusion amounted to 25 percent at a dislocation density of 4 x 10/sup 11//cm/sup 2/ and 5 percent at 5 x 10/sup 10//cm/sup 2/ when the intervoid spacing was larger than 2000 A. 12 figures, 2 tables.

Research Organization:
California Univ., Berkeley (USA). Lawrence Berkeley Lab.
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
7107907
Report Number(s):
LBL-4595
Country of Publication:
United States
Language:
English