silicon bronze A (Figure 34) were seriously decreased after 403 days 

 of exposure in the bottom sediment at a depth of 6,000 feet. This 

 decrease in mechanical properties is attributed to the severe selective 

 corrosion (coppering) of the alloy. 



Corrosion Products 



Chemical determinations of the corrosion products removed from 

 aluminum bronze showed the presence of copper oxy-cfiloride, cupric 

 chloride; major elements, copper and aluminum; minor elements, iron, 

 magnesium, calcium and silicon; chloride ion, 0.9%, and sulfate ion, 

 9 . 0% . 



COPPER-NICKEL ALLOYS 



The chemical compositions of the copper-nickel (Cu-Ni) alloys are 

 given in Table 14, their corrosion rates and types of corrosion in 

 Table 15, stress corrosion tests in Table 16 and changes in mechanical 

 properties due to corrosion in Table 17. 



Corrosion 



The corrosion rates and types of corrosion of the copper-nickel 

 alloys are given in Table 15 and are shown graphically in Figures 35 to 

 45. 



There were three different lots of 90 copper- 10 nick°el alloy 

 exposed at depths in the Pacific Ocean. As shown in Figure 35, their 

 corrosion rates in sea water at the 6,000 foot depth were comparab.le. 

 The corrosion rates of the specimens partially embedded in the bottom 

 sediments at the 6,000 foot depth were slightly lower than those in the 

 sea water. At the 2,500 foot depth the corrosion rates in sea water 

 were comparable with those in sea water at the 6,000 foot depth. In 

 the bottom sediment at the 2,500 foot depth the corrosion rates were 

 lower than those in the sea water. The corrosion rates after 181 days 

 of exposure at the surface in the Pacific Ocean at Point Mugu were 

 practically the same as those at both depths. At a depth of 5,600 feet 

 in the Atlantic Ocean, 90 copper-10 nickel alloy, after 110 days of 

 exposure, corroded at the same rate as at 6,000 feet in the Pacific 

 Ocean but, after 1050 days of exposure, its corrosion rate was much 

 less than in the Pacific Ocean, Reference 12. The same was true after 

 100 days of exposure at a depth of 4,250 feet in the Atlantic Ocean, 

 Reference 13, and after 200 days of exposure the corrosion rate was 

 slightly lower than in the Pacific Ocean. The corrosion was uniform 

 with the specimens being covered with thin light green flaky films of 

 corrosion products. 



The corrosion rates of the 70 copper-30 nickel with nominal 0.5 

 percent iron are shown in Figure 36. The corrosion behavior of this 



14 



