Characterization of simulated production welds in alloy 908
- Massachusetts Institute of Technology, Cambridge, MA (United States); and others
This study characterized room temperature mechanical properties of Incoloy{reg_sign} alloy 908* welds made from two base metal conditions: mill-annealed or homogenized (1050{degrees}C/1hr). An automatic pulsed-gas tungsten arc welder simulated actual conduit welding conditions. The weld fusion zone showed a typical cellular-dendritic microstructure with the precipitation of secondary phases within the interdendritic zone. Grain boundary liquation phenomenon was observed near the fusion boundaries in the heat affected zone. Complete resolidification of liquated grain boundaries prevented crack formation during welding. The tensile properties of the welds showed a strong dependence on the selection of the base metal used for welding. When the base metal was homogenized, the welds showed about the same amount of ductility as the homogenized base metal in the as-welded condition. Its strength was also higher than that of the surrounding homogenized base metal. The fracture toughness of welds was measured by the J-integral test technique. Unlike the tensile properties, the fracture toughness of the welds showed no dependence on the condition of the base metal. The fracture toughness of the welds was about 140 MPa{radical}m in the aged condition. The fatigue crack growth rates of aged production welds were comparable to those of the base metal. The fatigue crack growth threshold was measured to be about 3.7 MPa{radical}m for the as-welded production welds with homogenized base metal.
- OSTI ID:
- 476728
- Report Number(s):
- CONF-950722-; ISSN 0065-2482; TRN: 97:009219
- Journal Information:
- Advances in Cryogenic Engineering, Vol. 42A; Conference: CEC/ICMC `95: cryogenic engineering conference and international cryogenic materials conference, Columbus, OH (United States), 17-21 Jul 1995; Other Information: PBD: 1997
- Country of Publication:
- United States
- Language:
- English
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