The mechanical properties of columbium, molybdenum and tantalum were 

 not impaired . 



SUMMARY 



The purpose of this investigation was to determine the effects of 

 surface sea water on the corrosion of different types of alloys 

 (aluminum alloys, copper alloys, nickel alloys, steels, cast irons, 

 stainless steels, titanium alloys and miscellaneous alloys) for compari- 

 son with deep ocean corrosion behavior. To accomplish this 880 speci- 

 mens of 215 different alloys were exposed 5 feet below the lowest tide 

 level in the Pacific Ocean at Point Mugu, California (Site V) for a 

 period of 6 months. 



Aluminum Alloys 



The corrosion rates of the various aluminum alloys were not con- 

 sistently higher or lower at the surface than at depth in the Pacific 

 Ocean: those of 2219-T6 and 5086-H34 were higher at the surface while 

 those of 1100-H14, Alclad 3003 and 5052-0 were lower. The corrosion 

 rates of 3003, 5456-H321, 2024-0 and 6061-T6 were inconsistent in 

 that they were higher at one depth than at the surface and lower than 

 at the surface than at the other depth. 



Pitting corrosion was significant after six months of surface sea 

 water immersion on alloys 2024-0, 2219-T81, 3003-H14 and 5456-H321. 

 The maximum pit depths were deeper on more alloys at depth in the 

 Pacific Ocean than at the surface. 



Crevice corrosion was more severe at depth than at the surface for 

 all alloys except 2024-0. 



Alloys 2219-T81, 5083-H113, 5083-H32 : 5086-H34 and 6061-T6 were 

 attacked by intergranular corrosion. 



There was an overall increase in the corrosion rates of alloys 

 1100-H14, 3003, Alclad 3003, 5052-0, 5456-H321 and 6061-T6 with de- 

 creasing concentration of oxygen in sea water while those of 2024-0, 

 2219-T81, and 5086-H34 decreased with decreasing concentration of 

 oxygen after approximately 6 months of exposure. 



The mechanical properties of alloy 2219-T81 were impaired after 

 surface exposure in the sea water for 6 months. 



Copper Alloys 



The corrosion rates of the copper base alloys except cast nickel- 

 manganese bronze and 70-30 copper-nickel containing 0.5 percent iron 

 were higher at the surface than at depths of 2,500 and 6,000 feet in the 

 Pacific Ocean. 



The corrosion rates of the copper alloys except cast nickel- 

 manganese bronze and 70-30 copper-nickel containing 0.5 percent iron 



