highly alloyed nickel alloys are immune to corrosion, such as Ni-Cr-Fe 

 718, Ni-Cr-Mo 3 and 625, Ni-Mo-Cr "C", and Ni-Cr-Fe-Mo "F", "G" and "X" . 

 Ni-Co-Cr-Mo 700 alloy was attacked only by incipient crevice corrosion 

 after 400 days of exposure at a depth of 2,500 feet. 



The effect of depth on the corrosion of nickel alloys is shown in 

 Figures 13, 14 and 15. The corrosion rates of alloys Ni-Cr-Fe 610 (cast) 

 and 88 decreased with increasing depth, Figure 14. The corrosion rates 

 of alloys Ni-Cu 400, Ni-Cr 75, 65-35 and 80-20, and Ni-Cr-Fe 600 and X750 

 decreased from the surface to the 2,500-foot depth and remained constant 

 to the 6,000-foot depth, Figures 13, 14 and 15. All the other alloys ex- 

 cept Ni-Sn-Zn 23 and Ni-Si D were more affected by the oxygen concentra- 

 tion than by depth. The corrosion rates of Ni-Sn-Zn 23 and Ni-Si D al- 

 loys were higher at the 6,000-foot depth than either at the surface or at 

 the 2,500-foot depth, showing that neither depth nor oxygen were exerting 

 the major influence on the corrosion of these two alloys. 



The effect of the concentration of oxygen in seawater on the cor- 

 rosion rates of nickel alloys is shown in Figures 16, 17 and 18. The 

 corrosion rates of alloys electrolytic nickel, Ni-200, 201, 210, 211 

 and 301, Ni-Cu 402, 406, 410, K500 , K505 and 45-55, Ni-Cr-Fe X750 , 

 Ni-Mo-Fe "B", Ni-Cr 80-20, and Ni-Mo 2 decreased with decreasing con- 

 centration of oxygen in seawater as shown in Figures 16, 17 and 18. 

 The corrosion rates of some alloys decreased with the oxygen concentra- 

 tion to about 1.35 ml per liter and thereafter remained constant to 

 0.4 ml per liter - alloys Ni-Cu 400, Ni-Cr-Fe 600 and Ni-Cr 75. The 

 corrosion of alloys Ni-Sn-Zn 23 and Ni-Si Dare apprently not affected 

 to any major extent by the concentration of oxygen in seawater, Figures 

 17 and 18. 



The effect of time on the corrosion rates of some nickel alloys in 

 surface seawater is shown in Figure 19. The corrosion rates of alloys 

 Ni-200, Ni-Cu 400, Ni-Cr-Fe 600 and X750, and Ni-Fe-Cr 902 decreased 

 with increasing time of exposure. 



In general, pitting and crevice corrosion were more rapid in sur- 

 face exposure than at depth. 



Welding Ni-200 with electrode No. 141 and filler metal 61 resulted 

 in corrosion of the weld bead material and/or in the adjacent heat 

 affected zone. 



There was no accelerated corrosion of Ni-Cu 400 alloy or of the 

 weld beads when welded with electrodes 130 and 180; however, weld beads 

 of filler metal 60 and electrode 190 were attacked locally. 



The corrosion of Ni-Cu K500 alloy was not affected by welding with 

 electrode 64 at the 2,500-foot depth, but the weld beads from electrodes 

 64 and 134 were attacked during 540 days of exposure at the surface and 

 the weld bead of 134 electrode at the 2,500-foot depth. 



The weld beads on Ni-Cr-Fe 600 alloy made from electrodes 132, 182, 

 62 and 82 were selectively attacked during exposure at the surface and 

 at the 2,500-foot depth except the bead from electrode 182 at the 2,500- 

 foot depth which was only uniformly etched. 



