C77000 (ASTM B122) Alloy Data Specifications

An excellent spring material, C770 combines high strength with excellent stiffness, formability, corrosion resistance and solderability. These characteristics make it extremely adaptable to a range of spring applications including flat and slightly formed springs. It is also used for switches, jacks and relays; in food processing, hospital medical equipment and in ferrules. Perhaps the most "white" of the copper alloys, C770 finds use as decorative metal trim on saddles, harness, and belt buckles. For more information contact Olin Brass Market Development Engineering at 618-258-5255, OlinBrass.com or email us at info@olinbrass.com.

Chemical Composition

Copper1 53.5-56.5%
Nickel2 16.5-19.5%
Zinc Remainder
Iron 0.25% max
Lead 0.05% max
Manganese 0.50% max

1Copper includes Ag; Copper plus named elements, 99.5%

2Nickel values includes Co

Physical Properties

  English Units Metrics Units
Density 0.314 lb/in3 @ 68oF 8.70 g/cm3
Thermal Conductivity 17 BTU-ft/ft2-hr-oF 29 W/moK
Electrical Resistivity 189 ohm circ mils/ft 31.4 microhm-cm
Electrical Conductivity (annealed) 5.5% IACS* 0.0319 megamho/cm
Modulus of Elasticity 18,000,000 psi 124 kN/mm2
Thermal Capacity (Specific Heat) 0.090 Btu/lb/Fo @ 68oF 377.1 J/kg - oC @ 20oC
Coeff. of Thermal Expansion
  68-572oF (20-300oC) 9.3 PPM/oF 16.7 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 61-76 420-525 32 220 43 - -
1/4 Hard 69-87 475-600 63 435 26 0.8 0.8
1/2 Hard 78-95 540-655 78 540 14 1.0 1.0
3/4 Hard 88-101 605-695 92 635 8 1.5 1.5
Hard 92-107 635-740 98 675 4 2.0 2.0
Extra Hard 102-115 705-795 107 740 1 min 2.5 2.5
Spring 108-120 745-825 112 770 1 max 3.0 3.0
Extra Spring 116 min 800 min 115 min 795 min 1 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.