Port Hueneme Harbor, California, Reference 15; it was lower at the 

 latter site. The corrosion rates at the 6,000 foot depth, both in sea 

 water and in the bottom sediments, were comparable with that at the 

 surface in the Pacific at the Panama Canal Zone. The corrosion rate 

 of manganese bronze at the surface in the Pacific Ocean at Port Hueneme 

 Harbor, California, Reference 15, was comparable with that in sea 

 water at the 2,500 foot depth, both were lower than at the 6,000 foot 

 depth and at the Panama Canal Zone, There was negligible corrosion of 

 manganese bronze in the bottom sediments at the 2,500 foot depth. The 

 manganese bronzes were attacked to a considerable extent by dezincifi- 

 cation except that no dezincif ication was reported for the manganese 

 bronze in Port Hueneme Harbor. 



Cast nickel-manganese bronze was severely attacked by dezincifi- 

 cation after 402 days of exposure, both in the sea water and in the 

 bottom sediments, at a depth of 2,500 feet and after 751 days of ex- 

 posure in sea water at a depth of 6,000 feet. Figure 13. The corrosion 

 rate of the cast nickel-manganese bronze at the surface in the Pacific 

 Ocean was much less than at either depth. The extent of the dezincifi- 

 cation after 751 days of exposure at a depth of 6,000 feet is shown in 

 Figure 14. The light area on the cross sections depicts the dezincifi- 

 cation which is approximately 65 percent of the thickness of the speci- 

 men. 



The corrosion rate of aluminum brass decreased gradually with 

 increasing time of exposure in the sea water at the 6,000 foot depth. 

 Figure 15. After 181 days of exposure at the surface in the Pacific 

 Ocean, the corrosion rate was the same as in sea water at the 6,000 

 foot depth. In the bottom sediments at the 6,000 foot depth, the 

 corrosion rates also decreased with increasing time of exposure to 751 

 days, then increased sharply between 751 days and 1064 days. At the 

 2,500 foot depth the corrosion rate in sea water also decreased with 

 increasing time of exposure but in the bottom sediments it increased 

 slightly. However, after 400 days of exposure the corrosion rates 

 were the same in sea water and the bottom sediments at the 2,500 foot 

 depth and in the bottom sediment at the 6,000 foot depth. At the 4,250 

 foot depth in the Atlantic Ocean, Reference 13, the corrosion rate of 

 aluminum brass decreased slightly with time and was about the same as 

 that in the bottom sediments at the 6,000 foot depth. 



As shown in Figure 16, the corrosion rates of nickel brass de- 

 creased gradually with increasing time of exposure at both depths 

 (2,500 and 6,000 feet) except in the sediments at the 2,500 foot depth 

 where the alloy was practically uncorroded. Nickel brass corroded at 

 slower rates in the bottom sediments at both depths than in the sea 

 water and at slower rates at the 2,500 foot depth than at the 6,000 

 foot depth. It corroded at the surface in the Pacific Ocean at the 

 same rate as in the sediment at the 6,000 foot depth. 



There was one exception to the corrosion behavior which was common 

 to all the copper-zinc alloys; their corrosion rates in the bottom 



