Cupro Nickel 70/30 (UNS C71500) is a high-performance copper–nickel alloy containing approximately 70% copper and 30% nickel, with controlled additions of iron and manganese to enhance strength and corrosion resistance. This alloy offers excellent resistance to seawater corrosion, erosion, and biofouling, making it especially suitable for harsh marine and offshore environments. Cupro Nickel 70/30 maintains good mechanical strength at elevated temperatures and demonstrates outstanding resistance to stress corrosion cracking. It also provides excellent fabricability and weldability, allowing ease of manufacturing and installation. Common applications include seawater piping systems, heat exchangers, condensers, offshore platforms, shipbuilding components, desalination plants, and power generation systems where long service life, reliability, and resistance to aggressive saline conditions are essential.
CHEMICAL COMPOSITION OF CUPRO NICKEL 70/30 ROUND BAR
Grade
Cu
Ni
Fe
Mn
Pb
Zn
Cupro Nickel 70/30
65.0 min
29.0 – 33.0
0.40 – 1.00
1.00 max
0.05 max
1.00 max
MECHANICAL & PHYSICAL PROPERTIES OF CUPRO NICKEL 70/30 ROUND BAR
Density
Melting Point
Tensile Strength
Yield Strength (0.2% Offset)
Elongation
0.323 lb/in³ (at 68°F)
2260 °F (1240 °C)
50,000 psi (345 MPa)
20,000 psi (138 MPa)
30%
💡 Practical Difference in Use
Use Cupro Nickel 70/30 Round Bars when: superior resistance to seawater corrosion, erosion, and biofouling is required along with higher strength compared to 90/10 grades. Cupro Nickel 70/30 contains higher nickel content with iron and manganese additions, making it ideal for severe marine and offshore environments.
→ Example: seawater piping, condenser tubes, heat exchanger components, offshore platform parts, and marine engineering systems.
Bright Finished / Machined Cupro Nickel 70/30 Round Bars when: precise tolerances, smooth surface finish, and reliable performance in high-pressure or high-flow seawater systems are critical. Bright bars ensure uniformity, enhanced machinability, and consistent mechanical properties.
→ Example: valve components, precision shafts, marine fasteners, pump parts, and CNC-machined seawater fittings.
Applications of Cupro Nickel 70/30 Round Bars
Cupro Nickel 70/30 round bars are widely used in applications demanding maximum resistance to aggressive marine conditions.
Marine & Offshore: Seawater piping, fittings, and structural components.
Power & Desalination Plants: Condensers, heat exchangers.
Heavy Engineering: Shafts, fasteners, and corrosion-resistant parts.
When to Choose Cupro Nickel 70/30 Round Bars?
Selection depends on corrosion severity, seawater velocity, strength requirements, and service life expectations.
Choose Cupro Nickel 70/30 Round Bars when:
Maximum resistance to seawater corrosion and erosion is required
Higher strength than 90/10 grade is needed
Resistance to biofouling is critical
Used in high-flow or turbulent seawater systems
Long service life in harsh marine conditions is essential
