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FUSION WELDING OF END CAPS IN BERYLLIUM TUBES

Journal Article · · Welding J. (N.Y.)
OSTI ID:4722475
Beryllium appears attractive as a potential cladding material for fuel elements for advanced gas cooled reactor applications. As a result, a program was undertaken to develop procedures for successfully fabricating berylliumclad fuel elements and to determine the mechanical properties of these welds. Welding parameters affecting the integrity of tungsten-arc welds in 0.30 in. OD x 0.040 in. wall tubing were investigated. Based on a study of three joint designs, it was determined that the edge-fusion type proved to be better than either the butt- or plug-type design. To eliminate root cracking in the welds, it was necessary to obtain a very ttght fit-up of the end cap and tube by tapering the joint about 3 deg. Additional refinements such as preheating the joint to 1400 deg F under a suitable cover gas of argon reduced the propensity of crack formation and propagation during welding and cool-down. An evaluation of seven different lots of tubing produced by six fabrication processes showed that welds in extruded tubing exhibited a tendency to be porous, whereas welds in machined tubing did not. All the material tested had welds of comparable strengths, having shear strergth in the order of 20,000 psi at room temperature and 10,000 psi at 1100 deg F (593 deg C). To date, no service failures attributable to defective welds have been reported for approximately 300 tube-burst specimens tested in or out of the reactor. (auth)
Research Organization:
Oak Ridge National Lab., Tenn.
NSA Number:
NSA-17-008767
OSTI ID:
4722475
Journal Information:
Welding J. (N.Y.), Journal Name: Welding J. (N.Y.) Vol. Vol: 42
Country of Publication:
Country unknown/Code not available
Language:
English