C71500 Copper Nickel Metal Alloys

Standard Grade: C71500 (70-30 Cu-Ni Alloy, CuNi70/30)

UNS: C71500 (ASTM B111M, B122)

EN: CW354H (DIN 17663)

Applicable Standards: ASTM B111M, B122, B151M, B466M

High Corrosion Resistance: Excellent performance in seawater, weak acids, and high-temperature oxidation (corrosion rate ≤0.003 mm/a).

Mechanical Excellence: c71500 mechanical properties include tensile strength 350–550 MPa, elongation 20–40%.

Machinability: Supports cold/hot working, welding (TIG/MIG), and deep drawing; surface finish up to Ra 0.1µm.

Temperature Adaptability: Design temperature up to 377°C (annealed state), no brittleness at cryogenic conditions.

Industry-Leading Corrosion Resistance: Outstanding resistance to pitting and stress corrosion cracking in seawater and chemical media.

Multi-Scenario Adaptability: Operates reliably from –100°C to 377°C.

High Machining Flexibility: Compatible with welding, cold stamping, and forging.

Marine Engineering: Seawater cooler pipes, ship propellers, offshore platform components.

Chemical Equipment: Distillation towers, reactors, heat exchanger sleeves.

Power Industry: Nuclear plant condensers, heat exchangers.

Aerospace: Engine components, hydraulic system pipelines.

Welding: Prefer TIG or laser welding to minimize heat-affected zone brittleness.

Annealing: Post-cold working, anneal at 650–750°C; hot working temperature range: 900–1050°C.

Machining: Cutting speed ≤50 m/min; use carbide tools with oil-based coolant.

Q1: What is the difference between C71500 and brass?

C71500 offers superior corrosion resistance and strength compared to brass. Brass is a copper-zinc alloy, while C71500 is copper-nickel with 29-33% Ni. For seawater applications, C71500 resists pitting and stress corrosion cracking where brass would fail. However, C71500 is more expensive. Use C71500 for marine environments, brass for decorative or low-corrosion applications.

Q2: Is C71500 material welding feasible?

Yes, C71500 can be welded, but heat input must be controlled. The page specifies TIG or laser welding to minimize heat-affected zone brittleness. Use compatible filler wires (ERNi-7 recommended). For C71500 copper pipe, argon back-purge is required for the root pass. Do not overheat – keep interpass temperature below 150°C.

Q3: What is the corrosion resistance of C71500 in acidic environments?

C71500 resists weak acids but should not be used with strong oxidizing acids like nitric acid. The page states excellent performance in seawater and weak acids, with corrosion rate ≤0.003 mm/a. For strong oxidizing acids, the alloy will corrode rapidly. Always verify chemical compatibility before specifying C71500 for acid service.

Q4: What is the density of C71500 material?

C71500 density is 8.94 g/cm³. This is consistent across multiple sources. For weight calculation of C71500 copper pipe: (OD - wall) × wall × 0.0254 × 8.94 = kg/m. For imperial: 0.323 lb/in³. This high density contributes to the alloy's pressure tightness and acoustic damping.

Q5: What tensile strength can I expect from C71500?

Tensile strength of C71500 is 350–550 MPa depending on temper and form. Elongation ranges from 20–40%. Annealed material has lower strength but higher elongation; cold-drawn or half-hard tempers have higher strength. For C71500 copper pipe in half-hard condition, expect strength in the upper half of this range.

Q6: What is the maximum operating temperature for C71500?

Design temperature for C71500 is up to 377°C in annealed state. The page states no brittleness at cryogenic conditions. Above 377°C, creep strength decreases. For steam condenser and heat exchanger applications operating at 200-300°C, C71500 is a proven material. Short-term excursions above 377°C are tolerable but will accelerate annealing.

Q7: What are the common product forms and sizes for C71500?

C71500 is available as sheet (0.05–1.5mm), rod (3–120mm dia), tube (OD 2–150mm, wall 0.3–15mm), and wire (0.05–6.0mm). For C71500 copper pipe specifically, OD range is 2–150mm. Delivery conditions include cold-drawn, half-hard for tube; soft (M) or hard (H) for sheet; drawn or hot-rolled for rod.

Q8: What welding method is best for C71500 copper pipe?

TIG or laser welding is preferred to minimize heat-affected zone brittleness. The page specifies these methods. For field welding, TIG with ERNi-7 filler metal and argon back-purge is standard. Avoid oxyacetylene welding for critical seawater service as it may introduce carbon contamination.

Q9: Does C71500 contain iron? Why?

Yes, C71500 contains 0.4–1.0% iron to improve wear and fatigue resistance. Iron also enhances corrosion resistance in seawater by modifying the passive film. Without sufficient iron, 70/30 cupronickel loses its marine-grade performance. Always verify iron content on the mill test certificate.

Q10: What annealing temperature is required for C71500 after cold working?

Anneal C71500 at 650–750°C after cold working. Hot working temperature range is 900–1050°C. For tube products, annealing restores ductility and corrosion resistance. The page specifies these ranges. After annealing, cool in air or water quench depending on desired final properties.

Every batch of c71500 copper pipe requires the following inspections per ASTM B111M, B466M, and EN 12163:

C71500 copper pipe is packaged to prevent damage during transit:

Marking per bundle: Alloy (C71500 / 70/30), heat number, size (OD × wall), length, quantity, PO number, net/gross weight.

Moisture protection: Desiccant bags for tropical or long-term storage.

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