Sep 18 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesMechanical PropertiesThermal PropertiesOther DesignationsFabrication and Heat Treatment Machinability Welding Forging Hot Working Cold Working AnnealingApplications
Introduction
Copper beryllium alloys have good thermal and electrical conductivities and high strength. Two major groups of copper beryllium alloys include high conductivity alloys and high strength alloys. The high conductivity alloys have 0.2-0.7% of beryllium and large amounts of cobalt and nickel. The wrought high strength alloys consist of 1.6 to 2.0% of beryllium and nearly 0.3% of cobalt. Whereas the cast high-strength alloys contain up to 2.7% of beryllium. The cast alloys are designated as C82000 to C82800, and the wrought alloys are named as C17200 to C17400.
The copper beryllium alloys can be age hardened or precipitation hardened to obtain high strength. The cast alloys contain dendritic structure of alpha copper and beryllide phases. The wrought alloys have microstructure containing twinned grains of alpha copper with cobalt, nickel or cobalt and nickel beryllide particles dispersed in the structure.
The following section will give an outline of UNS C17000 beryllium copper alloys, which are ductile, heat treatable and can be mill hardened. These alloys are used in applications that require high strength and good conductivity.
Chemical Composition
The following table shows the chemical composition of UNS C17000 copper alloys.
Element |
Content (%) |
Cu |
98.1 |
Be |
1.7 |
Co |
0.20 |
Physical Properties
The physical properties of UNS C17000 copper alloys are given in the following table.
Properties |
Metric |
Imperial |
Density |
8.26 g/cm3 |
0.298 lb/in3 |
Melting point |
866°C |
1590°F |
Mechanical Properties
The mechanical properties of UNS C17000 copper alloys are tabulated below.
Properties |
Metric |
Imperial |
Tensile strength, ultimate |
483 - 810 MPa |
70100 - 117000 psi |
Tensile strength, yield (depending on temper) |
221 - 1172 MPa |
32100 - 170000 psi |
Elongation at break (in 76.2 mm) |
45.00% |
45.00% |
Modulus of elasticity |
115 GPa |
16700 ksi |
Poissons ratio |
0.3 |
0.3 |
Machinability (UNS C36000 (free-cutting brass) = 100%) |
20% |
20% |
Shear modulus |
50.0 GPa |
7250 ksi |
Thermal Properties
The following table shows the thermal properties of UNS C17000 copper alloys.
Properties |
Metric |
Imperial |
CTE, linear (@20.0 - 100°C/68.0 - 212°F) |
16.7 μm/m°C |
9.28 μin/in°F |
CTE, linear (@20.0 – 200°C/68.0 – 392°F) |
17.3 μm/m°C |
9.61 μin/in°F |
CTE, linear (@20.0 – 300°C/68.0 – 572°F) |
17.8 μm/m°C |
9.89 μin/in°F |
Thermal conductivity (@20.0°C/68.0°F) |
118 W/m-K |
819 BTU-in/hr-ft2°F |
Solidus |
865°C |
1590°F |
Liquidus |
980°C |
1800°F |
Other Designations
Other designations that are equivalent to UNS C17000 copper alloys include:
- UNS C17000
- ASTM B194
- ASTM B196
- ASTM B570
- SAE J461
- SAE J463
Fabrication and Heat Treatment
Machinability
The machinability rate of C17000 copper alloys is 20%.
Welding
Welding methods such as soldering, brazing, gas shielded arc welding, coated metal arc welding, spot welding, seam welding and butt welding are preferred for C170 copper alloys. Oxyacetylene welding is not preferred for this type of alloys.
Forging
C17000 copper alloys are forged at temperature ranging from 649 to 816°C (1200 to 1500°F).
Hot Working
C17000 copper alloys have good hot working property.
Cold Working
C17000 copper alloys have excellent cold working property.
Annealing
C17000 copper alloys are annealed at temperature ranging from 774 to 802°C (1425 to 1475°F).
Applications
The following are the major applications of UNS C17000 copper alloys:
Bearings |
Precision screw machined parts |
Plastic molds |
Electrical/electronic connectors |
Welding electrodes |
Corrosion resistant components |
Current-carrying springs |
Housings for magnetic sensing devices |