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Copper Alloy

C630 Nickel-Aluminum Bronze

C630 nickel-aluminum bronze combines high strength near 620 MPa with outstanding resistance to seawater, cavitation, and erosion. At 170 HB and 4.5/5 corrosion resistance, it is the workhorse copper alloy for marine propulsion and pumps, offering steel-like strength with the biofouling and corrosion behavior of bronze.

How C630 Nickel-Aluminum Bronze machines

Rated 2.5/5, the toughest of these copper alloys to cut. Its high strength and complex microstructure load tooling harder than brass or plain bronze, demanding rigid setups, sharp carbide, and moderate speeds. Plan for heavier cuts and shorter tool life than free-machining copper grades.

Manufacturing & processing

Versatile in production: CNC machining, sand and centrifugal casting, forging, and extrusion. Large marine propellers are typically cast then machined. It is weldable with appropriate technique and procedure control, an advantage for repairing or fabricating large marine structures.

Typical applications

Marine propellers, propeller shafts, rudder hardware, pump impellers and casings, valve components, and seawater piping fittings. Also used for high-strength fasteners, bearings, and bushings in marine and offshore service where erosion and corrosion would degrade lesser alloys.

When to choose it

Select C630 when a part sees both high mechanical load and seawater: it far outperforms brass and plain bronze on strength and erosion resistance. If the environment is benign, cheaper alloys suffice. Because it machines hard at 2.5/5, favor near-net casting or forging.

Suitable surface finishes

Common finishes for C630 Nickel-Aluminum Bronze: nickel plating, chrome plating, electropolishing, brushed. Use the finish selector →

FAQ

Why is nickel-aluminum bronze preferred for propellers?
It pairs roughly 620 MPa tensile strength with excellent resistance to seawater corrosion, cavitation erosion, and fatigue, plus good weldability for repair. Few materials hold up to the combined mechanical and erosive loading on a propeller blade while staying corrosion-stable, making C630 the marine industry default.
Can C630 be cast into large parts?
Yes. It is commonly sand-cast and centrifugally cast for large propellers, pump casings, and valve bodies, then finish-machined. Casting near net shape is often preferred precisely because its 2.5/5 machinability makes heavy stock removal slow and costly.
How does C630 corrosion resistance compare to stainless?
In seawater it resists chloride pitting and crevice attack and naturally inhibits biofouling, advantages over many stainless grades. However, super-duplex or 6-Mo stainless and nickel alloys can match or exceed it in some chemistries. Choose based on flow velocity, biofouling, and the specific corrosive medium.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.