If you are choosing between C63000 and C63200 for a turned or milled component that lives in seawater and carries heavy cyclic loads, spec C63200 when the failure mode you are guarding against is corrosion fatigue or galling against a stainless steel mating surface. The nickel-iron balance in C63200 shifts the intermetallic phase distribution in a way that measurably raises fatigue endurance in chloride environments. The trade-off: slightly lower ductility than C63000, and a machining experience that is equally unforgiving to tooling if you walk in expecting brass-like behavior.
What Is C63200 — Grade, Standards, and Chemical Identity
C63200 is a wrought nickel-aluminum bronze designated under the Unified Numbering System (UNS) with the composition CuAl11Fe6Ni6. It belongs to the aluminum bronze family within the broader copper alloy group — a family that shares nothing with steel, aluminum, or nickel superalloys in terms of density (approximately 7.6 g/cm³ at 20°C), thermal conductivity (roughly 36 W/m·K), or heat treatment response. Confusing these families will lead to wrong cutting parameters and scrapped parts.
The governing ASTM specification for C63200 rod, bar, and shapes is ASTM B150/B150M. For forgings, the applicable standard is ASTM B124/B124M. The cast equivalent widely used in marine specifications — particularly under MIL-B-24480 — is C95800 (UNS C95800). Direct substitution between wrought C63200 and cast C95800 requires engineering review because cast and wrought forms differ in grain structure, porosity risk, and fatigue behavior.
| Element | ASTM B150 C63200 (wt%) |
|---|---|
| Copper (Cu) | 78.5 min (balance) |
| Aluminum (Al) | 8.7–9.5 |
| Iron (Fe) | 3.5–4.3 |
| Nickel (Ni) | 4.0–4.8 |
| Manganese (Mn) | ≤1.5 |
| Silicon (Si) | ≤0.10 |
| Zinc (Zn) | ≤0.50 (residual) |
The defining metallurgical feature of aluminum bronzes in the 9% Al range is the formation of kappa (κ) intermetallic phases during cooling from hot-working. These complex Fe-Ni-Al intermetallics are what give C63200 its hardness, wear resistance, and the abrasive behavior that punishes cutting tools.
Mechanical Properties — ASTM B150 Baseline
The values below are minimum requirements per ASTM B150 for C63200 rod in the as-manufactured (M30) condition. Actual properties vary with section size, processing history, and whether the material has been hot-worked, cold-drawn, or annealed.
| Property | ASTM B150 C63200 Minimum | Standard |
|---|---|---|
| Tensile Strength | ≥620 MPa (90 ksi) | ASTM E8/E8M |
| Yield Strength (0.2% offset) | ≥275 MPa (40 ksi) | ASTM E8/E8M |
| Elongation in 4D | ≥10% | ASTM E8/E8M |
| Hardness (typical range) | 170–210 HB | ASTM E10; not a spec requirement |
Commercially supplied C63200 frequently exceeds these minimums — tensile strengths of 690–760 MPa (100–110 ksi) and yield strengths of 350–415 MPa (50–60 ksi) are common in hot-worked bar. If your design relies on values above the ASTM B150 minima, specify the properties on your drawing and purchase order; do not assume the mill will deliver above the standard floor.
Corrosion, Wear, and Galling Behavior
C63200 resists seawater corrosion through a protective aluminum oxide (Al₂O₃) surface film, not chromium passivation. This film is self-healing in aerated seawater, giving good performance in splash zones and submerged conditions. However, in stagnant or sulfide-rich seawater, the film can break down if flow velocities drop below approximately 1.5 m/s for extended periods — a constraint that applies to all aluminum bronzes regardless of nickel content.
Where C63200 earns its premium over simpler aluminum bronzes like C61400 is in cavitation erosion resistance. The hard kappa-phase particles act as crack-arresting barriers, reducing material removal under collapsing vapor bubbles. This makes C63200 a candidate for pump impellers and high-velocity valve internals — applications where lower-alloyed grades show measurable mass loss.
One under-appreciated property: C63200 exhibits excellent anti-galling behavior against stainless steel mating surfaces, including 316, 17-4PH, and Nitronic 60. If your assembly has a stainless-to-aluminum-bronze sliding interface, C63200 is a technically sound choice — the galling threshold stress is substantially higher than brass-on-stainless or stainless-on-stainless couples.
C63200 vs C63000 — When the Difference Matters
C63000 (CuAl10Fe5Ni5) and C63200 are close relatives on the same ASTM B150 table. The choice hinges on which failure mechanism matters most for your part.
| Comparison Point | C63200 | C63000 | Notes |
|---|---|---|---|
| Nominal Al content | 9.1% | 10.0% | C63000’s higher Al pushes more kappa phase volume |
| Nominal Fe content | 4.0% | 5.0% | Different Fe/Ni ratio changes kappa morphology |
| Nominal Ni content | 4.5% | 5.0% | Close — the ratio matters more than absolute values |
| Corrosion fatigue (seawater) | Marginally higher endurance limit | Good, slightly lower in cyclic seawater | Per NACE MR0175 and related marine alloy studies |
| Galling threshold | Excellent | Very good | Both far outperform stainless-on-stainless |
| Ductility (typical) | Slightly lower | Slightly higher | C63000 preferred where cold forming is required |
| Cost delta | ~5–15% premium | Baseline | Varies by mill, form, and quantity |
Rule of thumb: If your part experiences cyclic loading in seawater (pump shaft, offshore tensioner), lean toward C63200. For maximum ductility during cold forming, stay with C63000. Neither alloy should be specified in stagnant sulfide environments without confirming flow conditions.
CNC Machining C63200 — Practical Guidance
What Makes It Difficult
C63200 is not free-machining. Its machinability rating is approximately 30–40% of C36000 free-cutting brass — comparable to 316 stainless steel in difficulty but for different reasons:
- Tool abrasion: Hard kappa intermetallic phases (microhardness 300–400 HV) embedded in the ductile alpha-copper matrix cause progressive micro-scale abrasive wear on cutting edges. This is genuine abrasion, not built-up edge.
- Work hardening: Light finish passes under 0.2 mm DOC are especially vulnerable — the tool rubs rather than cuts, hardening the surface layer and accelerating edge wear.
- Chip control: Heavy cuts produce short brittle chips, but light finishing passes can generate stringy chips that wrap around the tool. Good chip-breaking insert geometry is essential.
- Heat concentration: At 36 W/m·K, C63200 conducts heat about twice as fast as stainless steel but far slower than pure copper — expect heat buildup at the tool tip if coolant delivery is inconsistent.
Tooling and Parameter Starting Points
The following are conditional starting references. Actual speeds, feeds, and tool life depend heavily on machine rigidity, tool holder type, coolant delivery method, workpiece geometry, and the exact heat number. Run test cuts and adjust.
| Operation | Starting Speed (m/min) | Starting Feed | Starting DOC (mm) | Tooling Notes |
|---|---|---|---|---|
| Rough turning | 90–150 | 0.15–0.30 mm/rev | 1.5–4.0 | Carbide, ISO K20 or uncoated with sharp positive edge; AlCrN coating at higher speeds; avoid TiN — delaminates under micro-impact |
| Finish turning | 120–180 | 0.05–0.15 mm/rev | 0.2–0.8 | Carbide with wiper geometry; DOC below 0.15 mm risks rubbing |
| Milling | 60–120 | 0.05–0.15 mm/tooth | 0.5–2.0 | Solid carbide, 4-flute variable helix; climb milling preferred |
| Drilling | 40–80 | 0.08–0.20 mm/rev | — | Carbide-tipped with through-coolant if depth >3×D; peck cycle beyond 4×D |
| Tapping | 5–12 | — | — | Spiral-flute taps; thread milling preferred for critical threads |
Coolant: Flood coolant with 8–10% soluble oil. Avoid chlorine-based EP additives if the part will see elevated-temperature seawater — risk of stress-corrosion cracking. Through-tool coolant at 50+ bar improves chip evacuation in deep bores.
Workholding: Elastic modulus approximately 120 GPa — less stiff than steel, stiffer than most brasses. Thin-walled parts deflect under clamping; use soft jaws and consider leaving 0.5 mm for a stress-relief finish pass after unclamping.
Surface Finishing and Treatment
C63200 does not form a passive chromium oxide layer; passivation per ASTM A967 does not apply. After machining:
- As-machined: Acceptable for many non-cosmetic marine parts. Ensure no embedded steel particles from tooling — pickle or clean mechanically if transfer is suspected.
- Electroless nickel plating: Specify per ASTM B733, typically 25 μm minimum for industrial environments.
- Shot peening: Beneficial for fatigue-critical parts. Specify intensity (Almen A), coverage (200%), and media per AMS 2430.
- Barrier coatings: Epoxy-based or copper-free antifouling systems for submerged service. Verify copper-alloy compatibility.
Typical Applications
- Marine propulsion: Propeller shaft sleeves, hub inserts, stern tube bearings — cyclic shaft loads in seawater.
- Offshore oil & gas: Riser tensioner bushings, subsea valve stems, connectors per API 6A.
- Aerospace landing gear: Bushings and wear plates — galling resistance against hardened steel pins combined with de-icing fluid exposure.
- Naval: Pump shafts, impeller wear rings, valve internals where machined-from-solid is preferred over castings.
- Heavy machinery: Wear plates, gibs, sliding blocks where loads exceed phosphor bronze capability.
Related Articles
- C63000 Nickel Aluminum Bronze: Machining & Selection for Marine Parts — direct sibling comparison
- C61400 Aluminum Bronze: Properties, Parameters & Marine Applications — lower-alloyed alternative
- CNC Machining C61300 (CuAl6Fe2): Parameters & Tooling Guide — leanest aluminum bronze
- Copper, Brass & Bronze Materials — full category
RFQ Checklist for C63200 Parts
- Material spec: “UNS C63200 per ASTM B150” (or B124 for forgings). Note product form.
- Condition: As-manufactured (M30), annealed, or cold-drawn. State required properties if above ASTM minimums.
- Quantity: Prototype vs. production changes process and tooling choices.
- Critical tolerances: C63200 moves under clamping — tolerance stacks need realistic allowances.
- Surface finish: Ra target on critical surfaces. Ra 0.4 μm on large bores adds significant cost.
- NDT requirements: Dye penetrant or ultrasonic (MPI not applicable — C63200 is non-magnetic). State acceptance standard.
- Certifications: EN 10204 3.1/3.2 material cert, dimensional report, any industry-specific paperwork.
- Surface treatment: Electroless nickel, shot peening, or coating — specify standard and thickness.
Send your drawings, material specification, condition, quantity, tolerances, and surface requirements for a technical review.
Turn this machining question into a manufacturable part
Need this material or process for your next CNC project?
Send your STEP, STP, IGES, DXF, PDF, material, quantity, surface finish, and tolerance requirements. We will review manufacturability and reply with practical quotation guidance.
