This alloy, a modification of the CDA-815 alloy, has an excellent combination of electrical and thermal conductivity and strength. CDA-815 permits 0.4-1.5% Chromium and the conductivity is increased by holding this to the low side.
The following properties are typical:
| Property | Range | |
| Tensile Strength (PSI) | 35-50,000 | |
| Yield Strength (PSI) | 23-40,000 | |
| % Elongation | 20-30 | |
| Hardness (RB) | 68-78 | |
| Electrical Conductivity (% I.A.C.S.) | 78-85 | |
| Thermal Conductivity (C.G.S.) | 0.77 | |
| Coefficient of Expansion (in/in C at R.T.) | 17x10-6 | |
| Density (Pounds/Cubic Inch) | .032 |
The chemical composition is:
| Chromium | 0.4 - 1.2 % | |
| Silicon | 0.15 max % | |
| Copper | Balance |
The castings are normally solution heat treated at 1865-1885 degrees F in a protective atmosphere. This dissolves the chromium and the rapid water quench which follows retains the chromium in solution. In this form, the alloy has poor conductivity and is soft. Aging 880-900 degrees F for one to five hours raises the hardness from below the RB scale to 68-78 RB and the conductivity increases from about 41% I.A.C.S. to about 85% I.A.C.S. If lower hardness is desired, the castings can be overaged to a softer condition without lowering the conductivity.
Modified Chromium Copper can meet the property requirements of Resistance Welders
Manufacturing Association Group A, Class 2.
This alloy’s high conductivity makes it ideal for applications such as arms for gun welders, circuit breaker parts, contact backings, and heat sinks for computer devices as well as other current carrying components.
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