UNDERSEA TECHNOLOGY 



49 



Specimen Depth 



Pacific Ocean 



5,500 teet 2,350 feet 



Alloy steels O • 



Cast irons A A 



Austenitic cast irons □ ■ 



Atlantic Ocean 



Surface 5,600 feet 



Wrightsville Beach, N. C. 



Mild steel /\ 



Carbon steel " 



High strength-low alloy steel ▼ 



1,200 



Exposure (days) 



The statistical median corrosion-rate curves for three 

 classes of alloys exposed in the Pacific Ocean are plotted to 

 show the effect of time at depth and the effect of depth in 

 seawater. Corrosion rates are given in mils per year. Surface 

 data for mild steel exposed in the Atlantic Ocean at Wrights- 

 ville Beach, N. C, and data from a depth of 5600 ft are shown 

 for comparison. The corrosion rates at both depths in the 

 Pacific decreased with increase in time of exposure. At a 

 nominal depth of 5500 ft, the rates became asymptotic with 

 time. 



