C360 and C464 copper material

1. Chemical Composition (Fundamental Distinction)

The primary difference lies in the presence of tin (Sn) (unique to C464) and variations in copper (Cu), zinc (Zn), and lead (Pb) content. These elements directly define the alloy's performance. Values align with industry standards (e.g., ASTM B16 for brass):

Element	C360 (Free-Cutting Brass; UNS C36000)	C464 (Naval Brass; UNS C46400)	Key Note
Copper (Cu)	60.0 – 63.0%	60.0 – 63.0%	Identical copper content, providing a baseline for ductility and corrosion resistance.
Zinc (Zn)	Balance (≈35 – 38%)	34.0 – 37.0%	C360 has slightly more zinc (boosts strength but may reduce corrosion resistance).
Lead (Pb)	2.5 – 3.7%	0.2% Max (Trace)	Critical difference: C360 has high lead for superior machinability; C464 is low-lead (avoids brittleness in high-stress applications).
Tin (Sn)	0.1% Max (Trace)	0.5 – 1.0%	Unique to C464: Tin is intentionally added to enhance corrosion resistance (especially against saltwater) and improve strength.
Iron (Fe)	0.15% Max	0.15% Max	Low iron content in both to prevent brittleness.

2. Mechanical Properties

Composition differences result in stark contrasts in strength, hardness, and ductility (values shown for annealed conditions, unless noted):

Property	C360 (Annealed)	C464 (Annealed)	Key Takeaway
Tensile Strength	~414 MPa (60,000 psi)	~448 MPa (65,000 psi)	C464 is ~8% stronger, thanks to tin addition.
Yield Strength (0.2% Offset)	~172 MPa (25,000 psi)	~193 MPa (28,000 psi)	C464 resists permanent deformation better under load.
Brinell Hardness (HB)	~85	~95	C464 is harder, improving wear resistance for structural parts.
Elongation (in 50 mm)	~30%	~25%	C360 is more ductile (easier to bend/form) due to higher lead and lower tin.
Fatigue Strength	Lower (prone to stress cracking in high-load cycles)	Higher (tin enhances resistance to repeated stress)	C464 is better for parts under cyclic loads (e.g., marine components).

3. Machinability

Machinability (ability to be cut/shaped with tools) is a defining difference, driven by lead content:

C360: Known as "free-cutting brass," its high lead content (2.5–3.7%) acts as a built-in lubricant during machining. It produces clean, chip-free cuts, minimizes tool wear, and enables high-speed production. It is one of the most machinable brass alloys, ideal for precision, high-volume parts.

C464: Low lead content (≤0.2%) makes its machinability significantly lower than C360. Cutting C464 requires slower speeds, sharper tools, and more frequent tool changes to avoid overheating or poor surface finish. It is not designed for high-volume machining but for structural performance.

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4. Corrosion Resistance

Corrosion resistance is critical for applications exposed to moisture or chemicals-here, tin content is game-changing:

C360: Offers good general corrosion resistance (e.g., in air, freshwater, or mild chemicals) but struggles in harsh environments. It is susceptible to dezincification (zinc leaching out, leaving porous copper) in saltwater or acidic conditions, and lead can leach in food-contact or potable water applications (restricting its use there).

C464: Classified as "naval brass," its tin addition provides excellent corrosion resistance-especially against saltwater, marine atmospheres, and mild industrial chemicals. It also resists dezincification better than C360, making it a staple for marine and coastal applications.

5. Typical Applications

Their divergent properties make them suited for entirely different use cases:

Alloy	Common Applications
C360	- Precision fasteners (screws, bolts, nuts, rivets) - Electrical connectors and terminals - Plumbing fittings (freshwater only) - Small machined parts (watch components, valve stems, instrument parts) - Hardware (hinges, knobs, brackets)
C464	- Marine hardware (boat propellers, rudders, hull fittings, anchor chains) - Coastal infrastructure (dock pilings, seawater pipes) - Industrial valves/pumps for saltwater or chemical processing - Structural components (fasteners for bridges in coastal areas) - Heat exchangers (low-pressure, corrosion-prone environments)