13, the corrosion rates were about one-half the corrosion rate at 5,600 

 feet in the Atlantic Ocean and about two- thirds the corrosion rate at 

 6,000 feet in the Pacific Ocean. They were more in agreement with the 

 NCEL corrosion rates of copper at the 2,500 foot depth in the Pacific 

 Ocean. 



At the 2,500 foot depth, the corrosion rates of copper as reported 

 by INCO, Reference 9, were the same as those at 6,000 feet. However, 

 the NCEL corrosion rates at the 2,500 foot depth were lower than those 

 at the 6,000 foot depth. In both cases the corrosion rates were practi- 

 cally constant with increasing time of exposure. 



The corrosion rate of copper was nearly constant with increasing 

 time of exposure at the surface in the Atlantic Ocean at Kure Beach, 

 North Carolina, Reference 14, but decreased with time of exposure at 

 the surface in the Pacific Ocean at the Panama Canal Zone, Reference 

 16, and became constant with time after about 4 years of exposure. 



At Port Hueneme Harbor in the Pacific Ocean, Reference 15, copper 

 corroded at a constant rate over a two year period of exposure. 



For practical purposes the corrosion of copper can be considered 

 constant and of the same magnitude after exposure for 1 year in sea 

 water at the surface and at depths in both the Atlantic and Pacific 

 Oceans. The corrosion rates ranged between 0.5 and 1.5 MPY with an 

 average of about 1 MPY. 



Copper partially embedded in the bottom sediments at the 6,000 

 foot depth corroded at essentially the same rate as in the sea water 

 at this depth as shown in Figure 4. The corrosion rate decreased with 

 increasing duration of exposure. At the 2,500 foot depth copper cor- 

 roded at a lower rate in the bottom sediment than in the sediment at 

 the 6,000 foot depth as well as in the water at 2,500 feet. 



The addition of about two percent beryllium to copper did not 

 affect the corrosion of copper after 402 days of exposure at a depth of 

 2,500 feet. The beryllium-copper was in the form of wrought sheet and 

 cast chain. Their corrosion rates were 0.6 and 0.5 MPY, respectively, 

 in sea water and 0.5 and 0.5 MPY, respectively, in the bottom sediments 

 while those of copper were 0.6 and 0.2 MPY in sea water and in the 

 bottom sediment, respectively. Table 3. The corrosion of the wrought 

 beryllium-copper sheet was not affected by welding either by the MIG or 

 TIG processes. 



Stress Corrosion 



Oxygen free copper was not susceptible to stress corrosion crack- 

 ing at stresses equivalent to 75 percent of its yield strength at a 

 nominal depth of 2,500 feet for periods of exposure to 402 days as 

 shown in Table 4. 



Mechanical Properties 



The effect of exposure on the mechanical properties of the coppers 



