susceptible to stress corrosion cracking at depths of 2,500 and 6,000 

 feet for periods of exposure of 400 days. 



Mechanical Properties 



The effects of exposure in the deep ocean environments on the 

 mechanical properties of the copper-nickel alloys are given in Table 

 17. The mechanical properties of none of the alloys were adversely 

 affected by exposures of 400 days at the 2,500 foot depth or of 



750 days at the 6,000 foot depth. 



Corrosion Products 



Qualitative chemical analyses of the corrosion products removed 

 from 70 percent copper-30 percent nickel-5 percent iron exposed for 



751 days at a depth of 6,000 feet showed that they were composed of 

 nickel hydroxide (Ni(0H)2); cupric chloride (Cu CI2); major elements, 

 copper and nickel; minor elements, iron, magnesium, sodium, and traces 

 of silicon and manganese; chloride ion as Cl, 4. 777,; sulfate ions as 

 SO4, 0.80%; copper as metal, 43.63%. 



SUMMARY AND CONCLUSIONS 



The purpose of this investigation was to determine the effects of 

 deep ocean environments on the corrosion of copper and copper alloys. 

 To accomplish this a total of 1050 specimens of 46 different alloys 

 were exposed at nominal depths of 2,500 and 6,000 feet for periods of 

 time varying from 123 to 1064 days. 



Copper 



Copper and beryllium-copper corroded uniformly at all depths but 

 copper was pitted during surface exposure in the Pacific Ocean at 

 Point Mugu. The corrosion rates were practically constant and of the 

 same magnitude after exposure for one year in sea water at the surface 

 and at all depths in the Atlantic and Pacific Oceans. In the bottom 

 sediments at the 6,000 foot depth the corrosion rates decreased with 

 increasing time of exposure and were the same as those in the sea 

 water after 35 months of exposure. At the 2,500 foot depth the cor- 

 rosion rates both in sea water and in the bottom sediments were lower 

 than at the 6,000 foot depth. Copper corroded at the same rate at the 

 surface in the Pacific Ocean at Point Mugu as at depth. 



The addition of 2 percent beryllium to copper did not affect its 

 corrosion rate. Neither MIG nor TIG welding affected the corrosion 

 rate of beryllium-copper. 



Copper was not susceptible to stress corrosion cracking at a depth 

 of 2,500 feet in the Pacific Ocean. 



18 



