Effect of temperature on the stress-relaxation response of a pressure vessel steel
Extensive cracking in the steam generator shells at Indian Point Station Unit 3 led to questions as to the effectiveness of the postweld heat treatment (PWHT) used during fabrication. A literature review revealed an absence of stress-relaxation data for the steels of interest, SA-302, grade B, and SA-533, grade B. This investigation was undertaken to characterize the stress-relaxation response at various PWHT temperatures and to determine the correlation, if any, with other measurable properties, such as hardness. A novel technique utilizing a closed-loop thermal-mechanical simulator, the Gleeble 1500, was developed and used. After producing a microstructure typical of a portion of the heat-affected zone (HAZ) of a weldment, we tested stress relaxation at eight temperatures, 482, 510, 538, 566, 593, 621, 649, and 677/sup 0/C (900, 950, 1000, 1050, 1100, 1150, 1200, and 1250/sup 0/F). We determined that 20 min (1200 s) was an adequate test time and that the magnitude of stress measured agreed with limited literature data for comparable materials. Substantial stress relaxation was noted at 593/sup 0/C (1100/sup 0/F) and above. Post-test hardness correlated very well with relaxation data.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6411028
- Report Number(s):
- NUREG/CR-3728; ORNL/TM-9149; ON: TI85003588
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
INDIAN POINT-3 REACTOR
STEAM GENERATORS
STEEL-ASTM-A302
STRESS RELAXATION
STEEL-ASTM-A533
CRACKS
HEAT TREATMENTS
MICROSTRUCTURE
ALLOYS
BOILERS
CRYSTAL STRUCTURE
ENRICHED URANIUM REACTORS
IRON ALLOYS
IRON BASE ALLOYS
POWER REACTORS
PWR TYPE REACTORS
REACTORS
RELAXATION
STEELS
VAPOR GENERATORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
210200* - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
360101 - Metals & Alloys- Preparation & Fabrication