CORROSION OF MATERIALS IN SURFACE SEAWATER AFTER 12 AND 18 MONTHS OF 

 EXPOSURE 



Technical Note N-1213 



YF 38.535.005.01.004 



by 



Fred M. Reinhart and James F. Jenkins 



ABSTRACT 



A total of 1150 specimens of 189 different alloys were completely 

 immersed in surface seawater for 12 and 18 months to obtain data for 

 comparison with deep ocean corrosion data. 



Corrosion rates, types of corrosion and pit depths were determined. 



Some highly alloyed nickel alloys, titanium alloys, silicon cast 

 irons, specialty stainless steels, columbium, tantalum and a tantalum- 

 tungsten alloy were uncorroded in seawater both at the surface and at 

 depth. 



The corrosion rates of the copper base alloys, nickel base alloys, 

 steels, cast irons, lead, tin, lead-tin solder, molybdenum and tung- 

 sten decreased with the concentration of oxygen in seawater, i.e., the 

 corrosion rates were lower at depth than at the surface. The corrosion 

 rates of Ni-200, Ni-Cu 402, 406, 410, K-500 and 45-55, Ni-Cr-Fe X750 , 

 Ni-Mo2, all steels, grey cast iron and alloy cast irons decreased 

 linearly with the concentration of oxygen in seawater. 



The copper base alloys, steels, cast irons, molybdenum, tungsten, 

 lead and lead-tin solder corroded uniformly both at the surface and at 

 depth. 



The aluminum alloys were attacked by pitting and crevice corrosion 

 and seawater was more aggressive at depth than at the surface for such 

 alloys. The effect of the concentration of oxygen in seawater on the 

 corrosion of aluminum alloys was inconsistent. 



The stainless steels were attacked by pitting, tunneling and crev- 

 ice corrosion, except 309, 316L, 317, 329, 6 33, 20Cb-3 and Ni-Cr-Mo-Si. 

 Surface seawater was more aggressive than seawater at depth in promot- 

 ing these types of corrosion on the stainless steels. 



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