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Effects of composition and temperature on irradiation hardening of pressure vessel steels

Conference ·
OSTI ID:49057
; ;  [1]; ;  [2]
  1. Univ. of California, Santa Barbara, CA (United States)
  2. Oak Ridge National Lab., TN (United States)
The effects of key metallurgical variables on the low fluence hardening in a set of A533B model steels were evaluated over a wide range of irradiation temperatures. Above about 163{degrees}C hardening increased with higher copper and nickel contents, as is typical of the pressure vessel operating regime around 290{degrees}C. However, at 121{degrees}C the hardening was generally lower and unaffected by copper and nickel variations. This observation of decreased hardening with lower temperature (e.g. an {open_quotes}inverted{close_quotes} temperature dependence) is tentatively attributed to a reduced contribution of copper precipitation. Tensile data for a set of commercial steels with a range of (uncontrolled) compositions also showed minimal sensitivity to copper variations at 121{degrees}C. Unlike the hardness data no systematic reductions in the yield stress increases were observed between 163 and 121{degrees}C. However, the ultimate tensile strength did decrease at the lower temperatures in the copper bearing steels, consistent with the hardness trends in the A533B alloys. The differences in yield stress versus hardness and ultimate tensile strength behavior could be attributed to a lower mechanical stability of small matrix defects, which presumably are the dominant microstructural feature induced by the lower temperature irradiations.
OSTI ID:
49057
Report Number(s):
CONF-910808--
Country of Publication:
United States
Language:
English