Copper alloys, cast

The UNS designations for cast copper alloys consist of numbers C80000 through C99999. Temper designations that define metallurgical condition, heat treatment, and/or casting method further describe the alloy. 

Copper alloys are not normally selected because of their corrosion resistance alone, but rather for that characteristic plus one or more other properties. In many applications, conductivity may be the deciding factor. 

The brasses are the most useful of the copper alloys. They find application in seawater with the higher-strength, higher-hardness materials used under 

The next major group of the copper alloys are the bronzes that, from a corrosion standpoint, are very similar to the brasses. Copper-aluminum (aluminum bronze), copper-silicon (silicon bronze), and copper-tin (tin bronze) are the main cast bronze alloys. The addition of aluminum to the bronzes improves resistance to high-temperature oxidation, increases the tensile properties, and provides excellent resistance to impingement corrosion. They are resistant to many nonoxidizing acids. Oxidizing acids and metallic salts will cause attack. Alloys having more than 8% aluminum should be heat treated because it improves corrosion resistance and toughness. Aluminum bronzes are susceptible to SCC in moist ammonia. 

Silicon bronze has approximately the same corrosion resistance as copper, but better mechanical properties and superior weldability. The corrosion rates are affected less by oxygen and carbon dioxide contents than with other copper alloys. Silicon bronzes can handle cold dilute hydrochloric acid, cold and hot dilute sulfuric acid, and cold concentrated sulfuric acid. They have better resistance to SCC than the common brasses. In the presence of high-pressure steam, silicon bronze is susceptible to embrittlement. 

However, in those cast alloys likely to be repaked or joined by welding (qv) some impurities can be very detrimental. On the basis of consumption, red brass alloys. Unified Numbering System (UNS) C 83600 (85%Cu, 5%Sn, 5%Pb, 5%Zn), UNS C 84400 (81%Cu, 3%Sn, 7%Pb, 9%Zn), and UNS C93200 (83%Cu, 7%Sn, 7%Pb, 3%Zn), are the most important of the cast copper alloys. 

Single-Phase Alloys. Copper—tin—zinc-lead alloys, tin bronzes, and the leaded tin bronzes have a narrow range of properties, namely, 

Alloys containing nickel and/or aluminum have high strength and the impact data may exhibit scatter if the cooling rate or composition has not been closely controlled. 

Polyphase Alloys. The two-phase alloys have a rather wide range of properties resulting from variations within the stmcture. If the second phase is distributed in critical depression, the hardness and strength are at a maximum and the ductility is at a moderate level. Tensile strength may be 415—825 MPa (60,000—120,000 psi) yield strength, 170—585 MPa (25,000—85,000 psi) and elongation, 10—40%. 

The effect of a second phase is demonstrated in the copper—aluminum system, where increasing aluminum concentration causes the alloy system to change to a polyphase alloy. By obtaining a fine dispersion of the phase, the yield strength is increased from 225 to 480 MPa (33,000—70,000 psi). 

Manganese bronzes and leaded manganese bronze (Cu-Zn-Mn-Fe-Pb) Silicon bronzes, silicon brasses (Cu-Zn-Si) 

Pure copper metal (oxygen-free electronic copper) ClOlOO 99.99+ 8941 69-365 221-455 4-55 42-96 1084 392 17.7 1.741 

Phosphorus deoxidized nonarsenical copper C10800 99.95Cu-0.009P 8940 69-345 221-379 4-50 54-82 1082 177 17.7 2.028 

Phosphorus deoxidized arsenical copper C14200 99.68Cu-0.35As-0.02P 8940 69-345 221-379 8-45 50 1082 177 17.4 3.831 

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COppERALLOYS - CAST COPPER ALLOYS] (Vol 7) Copper-tin-zinc-lead alloys... 

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