What Aluminum Bronze C61400 Is
Aluminum bronze C61400 is a copper-base alloy in which aluminum is the principal alloying addition, balanced by iron and small controlled amounts of nickel and manganese. A tough copper-rich matrix combined with iron-rich phases gives the grade a rare mix of mechanical strength, seawater corrosion resistance and wear resistance, which keeps it in demand for high-load and high-wear components.
Because the material work-hardens instead of turning brittle, it is produced both as wrought tube, plate, bar and forgings and as components machined from hot-worked stock. It is one of the standard aluminum bronze grades for seawater-cooled heat-transfer equipment and for pumps and valves in marine service.
Chemical Composition
| Element | Min, % | Max, % | Function |
|---|---|---|---|
| Cu | Balance | Remainder | Base metal |
| Al | 6.0 | 8.5 | Primary alloying element, oxide film |
| Fe | 1.5 | 3.5 | Strength and wear resistance |
| Ni | - | 0.6 | Optional, improves corrosion resistance |
| Mn | - | 1.0 | Optional, aids deoxidation |
| Zn | - | 0.50 | Impurity |
| Pb | - | 0.02 | Impurity |
| Sn | - | 0.20 | Impurity |
| Si | - | 0.10 | Impurity |
| Other impurities, total | - | 0.50 | Balance control |
Aluminum is the element that forms the protective film; iron refines the structure and strengthens it; nickel is optional and mainly improves corrosion resistance. Tight control of the impurity total is what keeps ductility and fatigue resistance predictable.
Mechanical Properties by Temper
| Property | Unit | O60 annealed | H04 hard drawn |
|---|---|---|---|
| Tensile strength | MPa (ksi) | 450 (65) | 655 (95) |
| Yield strength, 0.2 % offset | MPa (ksi) | 140 (20) | 310 (45) |
| Elongation in 50 mm | % | 40 | 15 |
| Hardness | HBW | 75 | 155 |
| Modulus of elasticity | GPa | 115 | 115 |
| Fatigue strength, reversed bending | MPa (ksi) | 130 (19) | 165 (24) |
| Machinability | % of free-cutting brass | 30 | 30 |
Strength is set by temper rather than by chemistry, so a purchase order should always state the temper. The annealed condition gives about 450 MPa tensile with 40 % elongation for forming operations; the hard-drawn condition reaches about 655 MPa tensile and 155 HBW for wear parts. Values above that range require a different alloy or a different product form and should be checked against the temper actually certified.
Why C61400 Resists Corrosion and Wear
Aluminum forms a dense oxide film that reforms when it is damaged, which suppresses pitting and stress-corrosion cracking in seawater and in many acidic media.
Iron additions of 1.5 to 3.5 % refine the microstructure and raise resistance to impingement and erosion, a decisive property for pump bodies and valve trim.
Work hardening is rapid, so hardness and strength rise with cold reduction and sliding-contact life far exceeds that of unalloyed bronze.
Corrosion fatigue performance in flowing seawater is markedly better than that of plain tin bronze, which matters for tube in high-velocity condensers.
Thermal and electrical conductivity remain adequate for heat-dissipation and current-carrying parts, although they are lower than those of pure copper.
Production and Typical Applications
Melting with full deoxidation keeps the composition uniform. Billets are then hot rolled or forged, and final properties are set by cold working or heat treatment, with hot working kept in a moderate temperature range to avoid the embrittling phases that form when the alloy is overheated.
Marine engineering: propellers, valves, pump bodies and seawater-resistant fittings.
Aerospace and transport: landing-gear bearings and high-temperature fasteners.
Power equipment: conductive springs and circuit-breaker contacts.
Mechanical manufacturing: gears, bearing bushes and mould inserts.
Heat-transfer equipment: condenser and heat-exchanger tube, tubesheets and baffles for seawater or brackish water duty.
Environmental systems: desulphurisation and wastewater treatment hardware.
Tube is commonly specified to ASTM B111 with the ASME SB111 equivalent, and wrought plate, sheet, bar and forging forms are supplied to UNS C61400 chemistry with temper properties agreed at order. Outside diameters range from a few millimetres to several hundred millimetres, with wall thickness from about 0.5 mm upwards according to the product form.
Frequently Asked Questions
Q: What is aluminum bronze C61400 made of?
It is a copper-base alloy with 6.0 to 8.5 % aluminum, 1.5 to 3.5 % iron, up to 0.6 % nickel and up to 1.0 % manganese, with zinc, lead, tin and silicon held as controlled impurities.
Q: How strong is C61400 compared with other bronzes?
Annealed stock is rated near 450 MPa tensile with 20 % proof stress around 140 MPa, while the hard-drawn temper reaches about 655 MPa tensile and 310 MPa proof stress, which is well above common tin bronze grades.
Q: Does C61400 resist seawater corrosion?
Yes. The aluminum-rich oxide film resists pitting and stress-corrosion cracking in seawater and brackish water, and its erosion resistance makes it suitable for pumps, valves and condenser tube in marine duty.
Q: Is C61400 easy to machine and weld?
Machinability is about 30 % of free-cutting brass, so carbide tooling and positive feeds are advised. The alloy welds and brazes with matching filler, and post-weld heat treatment is used where full corrosion resistance of the weld zone must be restored.
Q: What is the difference between C61400 and nickel aluminum bronze?
Nickel aluminum bronze grades contain substantially more nickel and are stronger and more resistant to severe seawater erosion, but they cost more and are harder to form. C61400 is the balanced choice for moderate to severe duty at lower cost.
Q: Which tempers are available?
O60 annealed for forming and bending, and H04 hard drawn for wear and load-bearing parts, together with intermediate tempers where a specific combination of strength and ductility is required.
