corrosion rates at the 2,500 foot depth were also essentially constant. 

 The corrosion rates in the sea water at the 2,500 foot depth were 

 essentially the same as those at the 6,000 foot depth while those in 

 the bottom sediments were slightly lower. The corrosion rate of G 

 bronze at a depth of 4,250 feet in the Atlantic Ocean, Reference 13, 

 was essentially the same as at the 6,000 foot depth after 200 days of 

 exposure. Both alloys (G and modified G bronze) corroded at higher 

 rates than at either depth when completely submerged at the surface in 

 the Pacific Ocean at Point Mugu, California. After 181 days of expo- 

 sure, their corrosion rates were the same (1.3 MPY) and were higher 

 than the average corrosion rate at the 6,000 foot depth by 0.9 MPY. 

 Both alloys corroded uniformly except for some crevice corrosion of 

 modified G bronze after 751 days of exposure in the sediment and 1064 

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



Two other bronzes, "M" and leaded tin bronze, similar in chemical 

 composition to modified G bronze, except for the addition of lead, 

 corroded similarly to the G bronzes as shown in Figure 23. A compari- 

 son of the curves in Figures 22 and 23 shows that they are practically 

 identical. "M" bronze corroded at essentially the same rate at a 

 depth of 4,250 feet in the Atlantic Ocean, Reference 13, as at a depth 

 of 6,000 feet in the Pacific Ocean. At the surface in the Pacific 

 Ocean the "M" bronze and leaded tin bronze corroded at higher rates 

 than at either depth as shown in Figure 23. The "M" and leaded tin 

 bronzes corroded uniformly except for severe general corrosion of the 

 leaded tin bronze specimen after 751 days of exposure at a depth of 

 6,000 feet. 



The corrosion rates of the phosphor bronzes, "A" and "D" , are 

 shown in Figure 24. They corroded uniformly and at the same rate at 

 both depths, 2,500 and 6,000 feet, both in sea water and in the bottom 

 sediments. The corrosion rate decreased between 123 and 400 days of 

 exposure and remained constant thereafter. Phosphor bronze "A", ex- 

 posed at a depth of 5,600 feet in the Atlantic Ocean, Reference 12, 

 corroded at the same rate as at the 6,000 foot depth in the Pacific 

 Ocean. Both bronzes corroded at higher rates at the surface in the 

 Pacific Ocean at Point Mugu, California than at either depth. Phosphor 

 bronze "A" corroded at higher rates at the surface in the Pacific Ocean, 

 in the Panama Canal Zone, Reference 16, and in Port Hueneme Harbor, 

 California, Reference 15, than at either depth in the Pacific Ocean. 

 The corrosion rates at both locations decreased asymptotically with 

 increasing time of exposure. Also, the corrosion rate of phosphor 

 bronze "A" in the surface sea water at Point Mugu after six months of 

 exposure was higher than in Port Hueneme Harbor. 



Wrought aluminum bronzes containing 5 and 7 percent aluminum 

 corroded at essentially the same rate irrespective of depth (2,500 and 

 6,000 feet) and whether or not they were in sea water or partially em- 

 bedded in the bottom sediments. Figure 25. The 5 percent aluminum 

 bronze also corroded at the same rate at both depths as it did at the 



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