Dissimilar-weld failure analysis and development. Comparative behavior of similar and dissimilar welds. Final report. [Welds of 2-1/4Cr-1Mo to 2-1/4Cr-1Mo using 2-1/4Cr-1Mo filler material; and austenitic to ferritic steel welds made by fusion welding alloy-800H to 2-1/4Cr-1Mo using nickel base filler metal ERNiCr-3]
The 593/sup 0/C (1100/sup 0/F) stress rupture behavior of similar metal welds (SMWs) and dissimilar metal welds (DMWs) was investigated under cyclic load and cyclic temperature conditions to provide insight into the question, ''Why do DMWs fail sooner than SMWs in the fossil fuel boilers.'' The weld joints of interest were an all ferritic steel SMW made by fusion welding 2-1/4Cr-1Mo to 2-1/4Cr-1Mo using 2-1/4Cr-1Mo filler metal and an austenitic to ferritic steel DMW made by fusion welding Alloy-800H to 2-1/4Cr-1Mo using a nickel base filler metal ERNiCr-3. The stress rupture behavior obtained on cross weld specimens was similar for both types of welds with only a 20% reduction in rupture life for the DMW. For rupture times less than 1500 hours, failures occurred in the 2-1/4Cr-1Mo base metal whereas, for rupture times greater than 1500 hours, failures occurred in the 2-1/4Cr-1Mo heat affected zone (HAZ). The HAZ failures exhibited a more brittle appearance than the base metal failures for both types of welds and it appears that the life of both joints was limited by the stress rupture properties of the HAZ. These results support the hypothesis that increased residual stresses due to abrupt changes in hardness (strength) of metals involved are the major contributors to the reduction in life of DMWs as compared to SMWs. 10 refs., 15 figs., 7 tabs.
- Research Organization:
- General Electric Co., Sunnyvale, CA (USA). Nuclear Systems Technology Group
- OSTI ID:
- 5549854
- Report Number(s):
- EPRI-CS-4666; ON: TI86920418
- Country of Publication:
- United States
- Language:
- English
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NICKEL ALLOYS
FAILURES
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360103* - Metals & Alloys- Mechanical Properties
200104 - Fossil-Fueled Power Plants- Components