C72500 (ASTM B122) Alloy Data Specifications

Developed by Bell Laboratories to solve issues of stress corrosion found in field parts, C725 has found application in the telecommunication industry for many years. A combination of very good fatigue strength and resistance to corrosion and tarnish have also made this alloy an excellent choice for other applications found in corrosive environments or applications requiring improved solderability. 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 Remainder
Nickel2 8.5-10.5%
Tin 1.8-2.8%
Iron 0.60% max
Lead 0.05% max
Manganese 0.20% max
Zinc 0.50% max

1Copper includes Ag; Copper plus named elements, 99.8%

2Nickel values includes Co

Physical Properties

  English Units Metrics Units
Density 0.321 lb/in3 @ 68oF 8.89 g/cm3
Thermal Conductivity 31 BTU-ft/ft2-hr-oF 54 W/moK
Electrical Resistivity 94.3 ohm circ mils/ft 15.7 microhm-cm
Electrical Conductivity (annealed) 11% IACS* 0.064 megamho/cm
Modulus of Elasticity 20,000,000 psi 138 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) 9.2 PPM/oF 16.6 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 45-65 310-450 21 145 35 - -
1/4 Hard 55-75 380-515 63 435 15 0.8 0.8
1/2 Hard 65-80 450-550 68 470 10 1.5 1.5
Hard 75-90 515-620 80 550 3 2.0 2.0
Extra Hard 80-95 550-655 85 585 2 2.3 2.5
Spring 85-100 585-690 90 620 1 min 2.5 3.5
Extra Spring 90-105 620-725 95 655 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.