THE PROPERTIES OF WELDED 18NI-7CO-5MO PLATE,
DOUGLAS AIRCRAFT CO INC SANTA MONICA CALIF
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An investigation was conducted to determine the fabricability of the 18Ni-7Co-5Mo alloy. Studies related to welding techniques, aging response, fracture toughness metallurgical considerations, and delayed failure susceptibility are presented. Finding indicate that High Energy inert-gas shielded metal-arc welding MIG techniques are completely adequate for the welding of 34-inch thick 18Ni-7Co-5Mo plate. Welds containing 1.0 titanium show less sensitivity to wide variations in aging cycle, with respect to standard mechanical properties, then do welds made with the nominal titanium content of the parent plate 0.5. The fracture toughness of welds is relatively insensitive to variations in welding technique, as well as weldmetal composition, when aged at 900F for 12 hours. The welds have poorer fracture toughness characteristics than the parent plate, and the fracture path appears to be associated with an unidentified phase found in the weldmetal. Welds and parent metal of the 18Ni-7Co-5Mo alloy are exceptionally resistant to delayed failure susceptibility when compared to AISI 4340 steel, at equivalent strength levels.