decreased as the concentration of oxygen in sea water decreased. 



Red brass, Muntz metal, and manganese bronze A were dezincified 

 after 6 months of surface exposure in sea water. There was no de- 

 zincif ication of red brass at depth; that of Muntz metal was more 

 severe than at depth and; it was the same at depth as at the surface 

 on manganese bronze A and cast nickel-manganese bronze. 



Dealuminif ication was present on 7 , 10 and 13 percent aluminum 

 bronzes, being more severe at the surface than at depth. 



There was slight crevice corrosion and pitting of some of the 

 alloys at the surface but none at depth. 



The mechanical properties were slightly lowered by exposure at 

 the surface but were unaffected at depth. 



Nickel Alloys 



Fourteen (14) of the nickel base alloys were uncorroded: nickel- 

 chromium-molybdenum alloys No. 3 and 625; nickel-cobalt-chromium alloy 

 700; nickel-chromium- iron alloy 718; nickel-iron-chromium alloys No. 

 800, 804, 825, 825 (sensitized), 825 Cb and 901; nickel- chromium- iron- 

 molybdenum alloys No. F, G and X; and nickel-molybdenum-chromium alloy 

 C. 



The corrosion rates of the other nickel base alloys were higher at 

 the surface than at depth in the Pacific Ocean. 



All except five of the corroded alloys were attacked by crevice 

 corrosion. 



The corrosion rates of the corroded alloys decreased as the con- 

 centration of oxygen in sea water decreased. 



The elongation of nickel- iron-chromium alloy 902 was lowered con- 

 siderably after six months of exposure at the surface. 



Steels 



The corrosion rates of the steels were higher at the surface than 

 at depths of 2,500 and 6,000 feet in the Pacific Ocean. 



The mechanical properties of the steels were not affected by ex- 

 posure in sea water for a period of six months. 



Cast Irons 



The silicon and silicon-molybdenum cast irons were uncorroded at 

 the surface and at depth in the Pacific Ocean. 



The corrosion rates of the other cast irons were higher at the 

 surface than at depth. The corrosion rates of the high nickel austen- 

 itic cast irons were lower than those of the other cast irons. 



The corrosion rates of the cast irons decreased with decreasing 

 concentration of oxygen in sea water. 



Type D-2C austenitic cast iron was attacked by interdendritic 

 corrosion. 



10 



