Minimum pressurization temperature of pressure vessels made of Cr-Mo steels
- Japan Steel Works, Ltd., Yotsukaido, Chiba (Japan). Technology Research Center
- Japan Steel Works, Ltd., Tokyo (Japan)
The variables contributing to startup procedure of reactor vessels made of Cr-Mo steels were examined. The methods to predict the toughness degradation of materials during long-term service from J-factor and step-cooling aging test were presented. Considering the effects of plate thickness and material damage due to high temperature creep and hydrogen embrittlement on fracture toughness, the master curves to predict the lower-bound fracture toughness K{sub IC} of 2 1/4Cr-1Mo, 1 1/4Cr-1/2Mo, 1Cr and 1/2Mo steels were obtained. The stress intensity factor K{sub I} of cracks penetrating into base metal was calculated considering the residual stress caused by the difference of thermal expansion coefficients between ferritic base metal and austenitic stainless steel weld overlay and by the construction welds such as internal and external attachment welds. Considering these variables, the minimum pressurization temperatures (MPT) of reactor vessels made of Cr-Mo steels were determined and for the analysis of warm startup procedure, the K{sub I} versus excess temperature diagrams were presented. From the historical change of J-factor of 2 1/4Cr-1Mo steels, the pressure vessels manufactured in past decades were classified into four generations and the MPT for each generation was determined.
- OSTI ID:
- 122647
- Report Number(s):
- CONF-950740--; ISBN 0-7918-1328-2
- Country of Publication:
- United States
- Language:
- English
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