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Brazed nickel/columbium dissimilar metal pipe joints for 720 C service

Journal Article · · Weld. J. (Miami); (United States)
OSTI ID:6467006

Direct brazing was investigated for fabricating Hastelloy X/Niobium alloy dissimilar metal pipe joints for possible use in a Brayton cycle space power system. These joints must remain leak-tight in space for up to seven years at 720/sup 0/C (1328/sup 0/F). Design and fabrication are complicated because of differences in composition and thermal expansion between the Ni- and Nb-base components. Two filler metals, selected from eight candidate compositions, were used to fabricate five different pipe joint configurations. Joint strength and integrity were evaluated as-brazed, after thermal aging, and after rapid thermal cycling. Results showed that direct brazing is a viable method for fabricating the dissimilar metal pipe joints. Best results were obtained using a tongue-in-groove joint design with a niobium alloy tongue and a BNi-4 filler metal.

Research Organization:
National Aeronautics and Space Administration, Cleveland, OH
OSTI ID:
6467006
Journal Information:
Weld. J. (Miami); (United States), Journal Name: Weld. J. (Miami); (United States) Vol. 56:10; ISSN WEJUA
Country of Publication:
United States
Language:
English