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Cast

TABLE 11.16 Examples of Copper and Copper Alloy Grades and Their Uses

Grade/Type

Comment and Uses

Wrought Al Bronze

Brasses

Cupro-nickels

8 Cu/5-10Al/2.5Fe. Marine, heat exchanger and superheated valve and pump components. Typical corrosion rates; (mm/y) seawater 0.05 (general), <0.05 (crevice).

Cu/10-30Zn. Used widely within mildly corrosive environments and atmospheres. Brasses are susceptible to dezincification, which is reduced on the addition of arsenic (0.04%), corrosion rates; (mm/y) 0.05 (general), <0.05 nickels (crevice).

Cu/10-30Ni/0.5-1.0Fe. Used extensively within marine environments, having excellent corrosion resistance in aerated, nonpolluted seawater. Cupro nickels have excellent resistance to marine biofouling. Typical corrosion rates; (mm/y) 0.025 (general), <0.025 (crevice). Polluted seawater and stagnant conditions can lead to accelerated corrosion via the action of microbial sulfate reducing bacteria (SRBs) >5 mm/yr.

for pumps, piping, and sheathing. Copper alloys are susceptible to SCC in the presence of ammonia or amines. In addition selective corrosion (dezincification) of the brasses (preferential corrosion of the Zn phase) can occur in fresh and seawater environments. Like Al, copper alloys are also found in both the wrought and cast forms. Table 11.16 presents a summary of the main Cu alloy types and their typical uses.

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