C68800 (ASTM B592) Alloy Data Specifications

Developed by Olin Metals Research Laboratories, C688 is a high strength copper-zinc alloy modified with aluminum and cobalt. With exceptional strength and non-directional formability C688 can be used in applications including: high end wiring devices, automotive connectors and electronic interconnections. Offering improved stress relaxation resistance compared to C260 this alloy offers improved reliability but designers considering applications with elevated service temperatures should also consider C4252 or C7025. For more information contact Olin Brass Market Development Engineering at 618-258-5255, OlinBrass.com or email us at info@olinbrass.com.

Chemical Composition

Copper 1 Remainder
Aluminum 3.0-3.8%
Cobolt 0.25-0.55%
Zinc 21.3-24.1%
Iron 0.20% max
Lead 0.05% max

1Copper plus named elements, 99.5% min

Physical Properties

  English Units Metrics Units
Density 0.296 lb/in3 @ 68oF 8.20 g/cm3
Thermal Conductivity 47.0 BTU-ft/ft2-hr-oF 81 W/moK
Electrical Resistivity 58.0 ohm circ mils/ft 9.6 microhm-cm
Electrical Conductivity (annealed) 18% IACS* 0.104 megamho/cm
Modulus of Elasticity 16,800,000 psi 116 kN/mm2
Thermal Capacity (Specific Heat) 0.090 Btu/lb/Fo @ 68oF 377.1 J/kg - oC @ 20oC
Coeff. of Thermal Expansion
  68-572o (20-300oC) 10.1 PPM/oF 18.18 PPM/oC

*International Annealed Copper Standard

Mechanical Properties

Temper1 Tensile Strength Yield Strength2 % Elongation2 Typical 90o Bend Formability GW/BW3
ksi N/mm2 ksi N/mm2
Annealed 77-87 530-600 52 360 35 - -
1/4 Hard 87-101 600-695 76 525 19 0.8 0.8
1/2 Hard 97-112 670-770 92 635 9 1.0 1.0
Hard 106-120 730-825 101 695 4 1.5 1.5
Extra Hard 113-127 780-875 108 745 2 3.0 3.0
Spring Hard 123-133 850-915 114 785 1 min 4.0 5.0
Extra Spring 125 min 860 min 112 min 770 min 2 max

1Mechanical properties subject to change. All tempers listed are made to a Tensile Strength specification unless otherwise noted.
2Nominal Values
3DATA FOR REFERENCE ONLY. R/T = Bend Radius/Material Thickness <0.016" (0.4mm) thick, 11/16 (17.5mm) wide.