Performance of Beryllium Copper

(6) Corrosion Resistance

In general, copper and its alloys have good corrosion resistance. Among various copper alloys, beryllium copper has excellent corrosion resistance and a low sensitivity to stress corrosion which can be serious for brass and nickel silver. Also beryllium copper has a better corrosion resistance against seawater than aluminum bronze or copper nickel. Therefore, beryllium copper is an ideal material when corrosion resistance and mechanical strength are required at the same time. A dense oxide film is formed on the surface of beryllium copper by age hardening and acts as protective coating. Thus, beryllium copper also shows good resistance against discoloration at a high temperature. Fig. 8 shows the magnitude of corrosion by salt water spray in comparison with other copper alloys. Phosphor bronze and copper titanium corrosion will advance at a much more rapid pace.

Fig. 8 Corrosion of Copper Alloys (Salt Water Spray)

Table 7. Approximate Corrosion Resistance of Beryllium Copper

Good (0.025mm / year max.)	Limited (0.025-0.25mm / year)	Poor (0.25mm / year min.)
Ammonia, dry Chloride, dry Sea water (RT) Gasoline Citric acid Acetic acid 0-1%(RT) Bromine, dry Steam Atmosphere, rural, industrial, marine	Hydrochloric acid, up to 5% Chlorine, moist (RT) Sea water (60°C) Acetic acid 2.5%-10% (RT) Sodium hydroxide up to 10% (RT) Bromine, moist (RT) Sulfur dioxide, moist, up to 10%(RT) Mine water Sulfuric acid, up to 10% (RT)	Ammonia, moist Ferric chloride Hydrochloric acid over 5% Chlorine, moist (ET) Chromic acid Bromine, moist(ET) Nitric acid Ammonium hydroxide Tin, (molton)