What is c71500 copper nickel?
c71500 copper nickel (also known as cupronickel 70/30) is a copper-nickel alloy containing 70% copper and 30% nickel. This copper nickel 70/30 has very good resistance to biofouling and marine corrosion, and possesses good fabricability. Copper gains more strength and corrosion resistance when nickel is added to it.
This Copper Nickel Alloy UNS C71500 is primarily used in seawater operations requiring forged and machined pump and valve components, hardware and fittings. However, it is more expensive compared to copper-aluminum alloys and other alloys with similar mechanical properties.
c71500 copper nickel chemical composition
The chemical composition of Copper Nickel Alloy UNS C71500 is simple compared to other copper alloys:
| Element | Content (%) |
|---|---|
| Copper (Cu) | 70 |
| Nickel (Ni) | 30 |
c71500 density and physical properties of 70/30 cupronickel
c71500 density = 8.94 g/cm³ (0.323 lb/in³).
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.94 g/cm³ | 0.323 lb/in³ |
| Melting point | 1171°C | 2140°F |
c71500 mechanical properties
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength (UTS) | 372 – 517 MPa | 54,000 – 75,000 psi |
| Yield strength (depending on temper) | 88.0 – 483 MPa | 12,800 – 70,100 psi |
| Elongation at break (in 381 mm) | 45% | 45% |
| Elastic modulus | 117 GPa | 17,000 ksi |
| Poisson's ratio | 0.34 | 0.34 |
| Shear modulus | 57.0 GPa | 8,270 ksi |
70/30 copper nickel thermal properties
| Property | Metric | Imperial |
|---|---|---|
| Thermal expansion coefficient (@20-300°C / 68-572°F) | 16.2 µm/m·°C | 9 µin/in·°F |
| Thermal conductivity (@20°C / 68°F) | 29 W/mK | 201 BTU·in/hr·ft²·°F |
70/30 copper nickel machinability
70/30 copper nickel machinability is rated at 20% (UNS C36000 free-cutting brass = 100%). This means:
Requires sharp carbide tooling
Lower cutting speeds compared to brass and free-cutting copper alloys
Abundant coolant is essential
Best for simple geometries – complex parts should be ordered as finished machined components
Equivalent standards for copper nickel alloy uns c71500
| Standard | Designation |
|---|---|
| ASME | SB111, SB171, SB359, SB395, SB466, SB467, SB543 |
| ASTM | B111, B122, B151, B171, B359, B395, B432, B466, B543, B552, B608 |
| Military | MIL C-15726, MIL T-15005, MIL T-16420, MIL T-22214 |
| Other | ASTM F467, ASTM F468, DIN 2.0882, SAE J461, SAE J463 |
Fabrication and heat treatment of c71500 material
Welding
The following processes are suitable for c71500 copper nickel:
Soldering and brazing
Oxyacetylene welding
Gas shielded arc welding (TIG/MIG)
Coated metal arc welding (MMA)
Spot welding, seam welding, and butt welding
Filler metal recommendation: Use ERNi-7 for best corrosion match and crack resistance.
Hot Working
Hot working capacity is good. Suitable temperature range: 927 – 1038°C (1700 – 1900°F) .
Cold Working
Cold working capacity is good. Can be cold reduced significantly, but will require annealing to restore ductility.
Annealing
Annealing temperature range: 649 – 816°C (1200 – 1500°F) .
Use for strain relief after cold working
Also used to restore corrosion resistance
FAQ
Q1: Is C71500 the same as 70/30 cupronickel?
Yes, C71500 is exactly 70/30 cupronickel. UNS C71500 contains 70% copper and 30% nickel by nominal composition. Some specifications add small amounts of iron and manganese (0.6-1.0% Fe, 0.5-1.5% Mn) for improved erosion resistance. Always check your required specification before ordering.
Q2: What is the difference between C71500 and C70600?
C71500 (70/30) has higher strength and better erosion resistance than C70600 (90/10). C71500 contains 30% nickel vs 10% in C70600. This gives C71500 higher tensile strength (372-517 MPa vs 303-414 MPa) and better resistance to high-velocity seawater (4-5 m/s vs 3-3.5 m/s). However, C71500 is approximately 25-30% more expensive. Use C71500 for high-velocity, turbulent, or polluted seawater conditions.
Q3: What is the density of C71500 material in g/cm³ and lb/in³?
C71500 density is 8.94 g/cm³ or 0.323 lb/in³. Some sources report 8.95 g/cm³ – the difference is minor and depends on exact composition. For weight calculations, use 0.323 lb/in³ for imperial or 8.94 g/cm³ for metric. For a 1" OD × 0.065" wall tube, weight is approximately 0.65 lb per foot.
Q4: What welding processes are suitable for C71500 copper nickel?
TIG (GTAW), MIG (GMAW), coated metal arc (MMA), soldering, brazing, spot welding, seam welding, and butt welding are all suitable. Oxyacetylene welding is also acceptable. Do not use carbon arc welding. For critical seawater applications, use TIG welding with ERNi-7 filler metal and argon back-purge for the root pass.
Q5: What is the annealing temperature for C71500 material?
Annealing temperature range is 649 – 816°C (1200 – 1500°F). Use this temperature range to soften cold-worked C71500 and restore ductility. Hold at temperature for sufficient time (typically 30-60 minutes per inch of thickness), then cool in air or water quench depending on the desired final properties.
Q6: Can C71500 be hot worked? What temperature range?
Yes, hot working capacity is good. The recommended hot working temperature range is 927 – 1038°C (1700 – 1900°F) . Do not work the alloy below the minimum temperature. Hot working processes include forging, extrusion, and hot rolling. After hot working, the alloy may be air cooled.
Q7: What are the main applications of Copper Nickel Alloy UNS C71500?
Primary applications are seawater and high-corrosion environments. UNS C71500 is used for forged and machined pump and valve components, marine hardware, fittings, condenser tubes, heat exchanger tubes, and seawater piping. It is also used where chloride stress-corrosion cracking prevents use of stainless steels.
Q8: What is the thermal conductivity of 70/30 copper nickel?
Thermal conductivity is 29 W/mK at 20°C (68°F). This is approximately 1/12 that of pure copper (C12200 at 340-360 W/mK). In heat exchanger applications, this lower conductivity means you need more surface area compared to pure copper. However, the alloy's superior seawater corrosion resistance often makes it the preferred choice.
Q9: What is the yield strength of C71500 in annealed condition?
Yield strength in annealed condition is approximately 88-140 MPa (12,800-20,300 psi). The exact value depends on product form and specific manufacturing process. For comparison, hard drawn C71500 can have yield strength up to 483 MPa (70,100 psi). Always request a mill certificate to confirm actual properties for your specific lot.
Q10: Is C71500 suitable for chloride stress-corrosion cracking environments?
Yes, C71500 is highly suitable where chloride SCC prevents use of stainless steels. Copper-nickel alloys, including C71500, are immune to chloride stress-corrosion cracking. This makes them ideal for seawater systems, marine environments, and chemical processing with chlorides. Use C71500 instead of 304 or 316 stainless steel when chloride SCC is a concern.
Detection & Quality Control
| Test Method | Purpose | Acceptance Criteria |
|---|---|---|
| Optical Emission Spectrometry | Verify c71500 chemical composition | Cu 70% ±, Ni 30% ± (plus Fe and Mn if required) |
| Tensile Testing | Confirm c71500 mechanical properties | UTS 372-517 MPa, Yield 88-483 MPa (depends on temper) |
| Hardness Test | Uniformity of heat treatment | Varies by temper – confirm with supplier |
| Eddy Current Testing (for tube) | Detect pits, cracks, wall variations | Per ASTM E243 |
| Hydrostatic Test (for tube/pipe) | Leak tightness | To specified pressure, no leakage |
| Dimensional Check | OD, wall thickness, straightness | Per applicable ASTM standard |
Packaging
| Packaging Type | Length Range | Details |
|---|---|---|
| Hexagonal bundles | 5 – 24 meters | Steel straps every 1.5m, plywood separators between layers, red plastic end caps (color code for C71500). Max bundle weight 2000 kg. |
| Wooden reels (coiled tube) | Up to 300 meters continuous | ISPM-15 certified wooden reels, VCI paper + stretch film wrap. Reel flange marked with heat number, size, and length. |
| Steel crates | 1 – 6 meters (cut lengths) | Stackable up to 2 high. Each tube individually sleeved in plastic. Crates bolted, not nailed. |
| Export wooden cases | Pre-fabricated spools, fittings | ISPM-15 certified, foam-lined interior, each piece individually labeled. |
Factory Equipment
| Equipment | Specification | Role in C71500 Pipe Production |
|---|---|---|
| Induction melting furnaces | 6 tons, argon atmosphere stirring | Precise c71500 chemical composition control, minimizes gas porosity and inclusions |
| Horizontal continuous caster | 200 mm diameter billet | Produces solid round billet specifically for tube extrusion |
| Extrusion press | 3500 ton capacity | Pierces billet to produce hollow shell (tube blank). Tooling for OD 30-250 mm. |
| Cold pilger mills | 6 stands, max product length 40 m | Reduces tube OD and wall thickness with high precision, improves mechanical properties. Can reduce OD by up to 75% in one pass. |
| Draw benches | 30 ton and 60 ton capacities | Final sizing of tube OD and wall. Produces smooth internal surface finish. Straightness achieved to 0.5 mm per meter. |
| Car bottom annealing furnace | 650-850°C, rapid water quench | Solution annealing after cold work – restores corrosion resistance and ductility. Temperature uniformity ±10°C. |
| Tube straightening machines | 6-roll rotary type | Corrects bending introduced during drawing. Achieves straightness 0.5 mm/m or better. |
| Eddy current tester | 100% online inspection, rotating probe | Detects pinholes, slivers, wall variations, longitudinal and transverse defects. Marks rejects with spray paint. |
| Ultrasonic tester | Rotating head, 4 channels | Laminar flaw detection and wall thickness mapping. Used for high-pressure or naval grade tube. |
| Hydrostatic tester | Pressure up to 6000 psi | Leak tests every tube individually. Holds pressure for minimum 5 seconds with automated pressure recording. |
| Tube cutting and end finishing line | Automatic saw + beveling unit | Cuts to customer length, prepares ends (plain, beveled, or grooved). |
| Metallurgical laboratory | OES spectrometer, universal tensile tester, hardness tester, microscopes, corrosion test setup | In-process and final quality verification. All equipment calibrated annually. |
Our Full Product Rang
| Product Form | Common Standards | Typical Alloy Grades | Size Range | Typical Applications |
|---|---|---|---|---|
| Copper Pipe & Tube (Seamless) | ASTM B111, B466, ASME SB111, SB466, EN 12451 | C71500, C70600, C12200, C68700, C44300, C19200 | Pipe: 6-219 mm OD × 0.5-12 mm wall; Tube: 6-50 mm OD × 0.5-3 mm wall | Condensers, heat exchangers, seawater piping, hydraulic lines, fire mains |
| Copper Wire | ASTM B624, B470, EN 13601 | C10100 (OFHC), C11000, C18200, C71500, C70600 | Diameter: 0.1 – 12 mm; Round, square, rectangular | Electrical conductors, welding filler wire, mesh, fasteners, rivets |
| Copper Strip & Coil | ASTM B152, B465, EN 13599 | C11000, C26000 (brass), C26800, C71500, C70600, C51100 | Thickness: 0.1 – 6 mm; Width: 10 – 600 mm | Transformer windings, gaskets, spring contacts, architectural cladding, heat exchanger fins |
| Copper Rod & Bar (Round / Hex / Square) | ASTM B151, B124, EN 12163, 12164 | C71500, C70600, C36000 (free-cutting), C46400 (naval brass), C63000, C17200 | Diameter: 5 – 200 mm; Length: 1 – 6 m | Valve stems, pump shafts, fasteners, gears, marine hardware, CNC blanks, bolts |
| Copper Plate & Sheet | ASTM B171, B402, EN 1652 | C71500, C70600, C46400, C63000, C17200, C10100 | Thickness: 3 – 100 mm; Width: up to 2000 mm; Length: up to 6000 mm | Tube sheets, baffle plates, flange faces, pressure vessels, ship hulls, marine platforms |
| CNC Machined Components | Custom drawing; Materials to ASTM/ASME | C71500, C70600, C36000, C63000, C17200, C10100, C18200 | Custom dimensions; Tolerance up to ±0.01 mm | Manifold valve blocks, pump housings, impellers, connectors, custom fittings, marine hardware |
