The ductile-brittle transition behavior of submerged-arc weldments following high temperature exposure

Conference · Fri Oct 01 04:00:00 EDT 1999

OSTI ID:679487

Beere, W B; Bolton, C J; Jones, R B ^[1]; Fidler, R S; Fenton, S T ^[2]

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1. Magnox Electric plc, Berkeley (United Kingdom)
2. Nuclear Electric Ltd., Barnwood (United Kingdom)

The paper analyzes data derived from surveillance specimens withdrawn periodically throughout the life of Magnox reactors with the objective of establishing a predictive equation for the end of life Charpy impact properties of the submerged-arc welds in the ferritic steel pressure vessels. Theoretical arguments and experimental data show that the transition temperature shifts in welds exposed in high temperature (360 C and above) low irradiation dose ({approximately}0.4 mdpa) locations are controlled by thermally-induced intergranular fracture due to phosphorus segregation. The available data have been analyzed as a function of time-at-temperature and a trend curve has been developed, taking into account both the time and temperature of exposure before and after a temperature decrease early in life. Data analysis showed that a threshold time condition should be allowed for, which must be exceeded before a shift in transition temperature is observed. This was interpreted as a threshold level of phosphorus segregation which had to be reached before intergranular fracture could take place in preference to cleavage fracture.

• OSTI ID: 679487
• Report Number(s): CONF-960643--
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
36 MATERIALS SCIENCE
CHARPY TEST
DATA ANALYSIS
DUCTILE-BRITTLE TRANSITIONS
EMBRITTLEMENT
MAGNOX TYPE REACTORS
MICROSTRUCTURE
PHYSICAL RADIATION EFFECTS
PRESSURE VESSELS
REACTOR MATERIALS
WELDED JOINTS