roughening of weld bead indicating that weld beads ina.de with this 

 composition electrode are compatible (the same corrosion potential 

 in sea water) with the parent metal and is the preferred welding 

 electrode. 



After 402 days of exposure in the sea water at a depth of 

 2,370 feet, there was tunnel corrosion in the heat-affected zone and 

 along the edge of the weld bead in alloy X750 which had been welded 

 with electrode 718 by the tungsten electrode inert gas welding 

 process. When alloy X750 was welded with electrode 69 by the tungsten 

 electrode inert gas welding process there was no selective attack 

 of the weld bead material or in the heat affected zone. 



There was no visible corrosion on alloy 718 unwelded and when 

 welded with electrode 718 by the tungsten electrode inert gas weld- 

 ing process after 402 days of exposure in the sea water at a depth 

 of 2,370 feet. 



Nickel-Iron-Chromium Alloys 



There was either no visible corrosion or there was crevice cor- 

 rosion varying from incipient to 35 mils deep on alloys 800, 804, 

 825, 825 sensitized (heated for 1 hour at 1200OF), 825 Cb, 901 and 

 902, Table 9, There was crevice corrosion 6 mils deep on alloy 800 

 after 1064 days of exposure in the bottom sediment at a depth of 

 5,300 feet; only incipient crevice corrosion on alloys 804, 825 Cb 

 and 901 at both depths, crevice corrosion 22 mils deep on alloy 825 

 after 751 days of exposure in the sea water at a depth of 5,640 feet; 

 crevice corrosion 4 mils deep on alloy 825 (sensitized) after 1054 

 days of exposure in the bottom sediment at a depth of 5,300 feet; 

 and crevice corrosion 35 mils deep on alloy 902, after 402 days of 

 exposure in the sea water at a depth of 2,370 feet. 



The U. S. Navy Marine Engineering Laboratory found essentially 

 the same corrosion behavior of alloy 825 which was exposed on STUs 

 1-3 and 1-2 for 123 and 751 days at a depth of 5,640 feet, Reference 

 8. Crevice corrosion was 63 mils deep (perforated) after 751 days 

 with scattered pitting to 1 mil deep. There was crevice corrosion 

 to 57 mils deep aad scattered pitting to a depth of 2 mils after 

 386 days of exposure of companion specimens at the surface at 

 Harbor Island, North Carolina. These data indicate that the corro- 

 sion of alloy 825 is slightly faster at the surface in the Atlantic 

 than at depth in the Pacific. 



The corrosion behavior of these alloys was the same both in 

 sea water and in the bottom sediments. 



