same rates and in the same manner as the alloy in 

 sheet form. Welding by either the TIG or MIG pro- 

 cesses as well as aging at either 600°F or 800°F did 

 not affect the corrosion behavior of the beryllium- 

 copper alloys. 



3.1.2. Effect of Depth 



The effect of depth on the corrosion of copper is 

 shown in Figure 9. The corrosion of copper was not 

 affected by depth, at least to a depth of 6,000 feet. 



3.1.3. Effect of Concentration of Oxygen 



The effect of the concentration of oxygen in sea- 

 water on the corrosion of copper is shown in Figure 

 10. The corrosion of copper was unaffected by the 

 concentration of oxygen in seawater within the range 

 of 0.4 to 5.75 ppm. 



3.1.4. Stress Corrosion 



Copper and beryllium-coppers were exposed in 

 the seawater while stressed at values equivalent to 30 

 and 75% of their respective yield strengths for the 

 periods of time and at the depths shown in Table 12. 

 Neither copper nor the beryllium-coppers were sus- 

 ceptible to stress corrosion. Aging at either 600°F or 

 800°F did not affect the stress corrosion resistance of 

 beryllium-copper (CDA No. 172). 



3.1.5. Mechanical Properties 



The effects of exposure in seawater on their 

 mechanical properties are given in Table 13. The 

 mechanical properties of the copper and the 

 beryllium-coppers were not significantly affected by 

 exposure in seawater at the surface or at depth. 



3.1.6. Galvanic Corrosion 



Dissimilar metal couples consisting of 1 x 2-inch 

 strips of aluminum alloy 7075-T6 fastened to 

 1 x 6-inch strips of beryllium-copper alloy (CDA No. 

 175) with plastic fasteners were exposed in seawater 

 at a depth of 2,500 feet for 402 days. After exposure 

 the 7075-T6 was covered with a heavy uniform layer 

 of corrosion products, while there was a thin layer of 



corrosion products on the CDA No. 175 alloy. This 

 indicates that the aluminum was corroding galvani- 

 cally to protect the beryllium-copper from corroding. 



3.2. BRASSES (Copper-Zinc Alloys) 



The chemical compositions of the brasses are 

 given in Table 14, their corrosion rates and types of 

 corrosion in Table 15, their resistance to stress cor- 

 rosion cracking in Table 16, and the changes in their 

 mechanical properties due to corrosion in Table 17. 



3.2.1. Duration of Exposure 



The effects of the duration of exposure on the 

 corrosion of the brasses in seawater at depth, at the 

 surface, and in the bottom sediments are shown in 

 Figure 1 1. 



Since the corrosion rates of all the brasses, except 

 those of alloys, CDA No. 280 and 675, were so com- 

 parable, the average values for any one time, depth, 

 or environment were used to prepare the curves in 

 Figure 11. The corrosion rate values of alloys CDA 

 No. 280 (Muntz Metal) and CDA No. 675 (manganese 

 bronze A) were considerably higher than those of all 

 the other brasses. These high rates were attributed to 

 the severe parting corrosion (dezincification) which 

 had occurred on these two alloys. 



The curves in Figure 1 1 show the effects of the 

 duration of exposure on the corrosion of the brasses 

 in seawater. The corrosion rates of the brasses 

 decreased slighdy with increasing duration of 

 exposure at the surface and at depths of 2,500 and 

 6,000 feet both in seawater and in the bottom 

 sediments. The corrosion of the brasses was the same 

 in the bottom sediments as in the seawater at the 

 6,000-foot depth, but slower in the bottom sediments 

 than in the seawater at the 2,500-foot depth. The 

 corrosion in seawater was practically the same at the 

 2,500-foot depth as at the 6,000-foot depth. The 

 brasses corroded slighdy slower at depth than at the 

 surface. 



3.2.2. Parting Corrosion (Dezincification) 



The alloys attacked by parting corrosion are 

 shown in Table 15. All the brasses, except Arsenical 



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