What C26000 Yellow Brass Is
C26000 is the classic 70 % copper, 30 % zinc alloy known as cartridge brass or yellow brass. Of all the plain copper-zinc alloys it is the most ductile, and it is consumed in larger quantities than any other brass composition. In flat bar form it is supplied as a rolled product under ASTM B36/B36M and is used wherever a combination of formability, corrosion resistance, electrical conductivity and an attractive yellow finish is required. The alloy is easy to identify in the workshop: it solders and brazes readily, cold forms without cracking, machines to a reasonable finish and takes electroplating or polishing well.
Chemical Composition and Equivalent Grades
The ASTM B36/B36M limits for C26000 are stated in the table below. Zinc makes up the balance of the composition.
| Element | Copper | Lead | Iron | Zinc |
|---|---|---|---|---|
| Minimum, % | 68.5 | - | - | remainder |
| Maximum, % | 71.5 | 0.07 | 0.05 | - |
| Nominal, % | 70.0 | - | - | 30.0 |
Because C26000 is widely traded, equivalent designations in other systems are useful when a drawing quotes a European or Asian standard:
| System | ASTM | EN | BS | DIN | JIS | ISO |
|---|---|---|---|---|---|---|
| Designation | C26000 | CW505L | CZ106 | 2.0265 | C2600 | CuZn30 |
Physical and Mechanical Properties
C26000 combines moderate strength with high elongation. The values below are the minimum requirements routinely quoted for flat bar: a tensile strength of 345 MPa, a yield strength of 205 MPa measured at 0.5 % extension under load, and a minimum elongation of 20 %. Because the alloy is produced in several tempers, from annealed through quarter hard and half hard to hard and spring temper, the temper must always be stated on the order together with the ASTM B36/B36M designation.
| Property | Value |
|---|---|
| Tensile strength, minimum | 345 MPa (50 ksi) |
| Yield strength at 0.5 % extension under load, minimum | 205 MPa (30 ksi) |
| Elongation, minimum | 20 % |
| Typical hardness | 55 HRB |
| Density | 8.53 g/cm³ |
| Modulus of elasticity | approx. 110 GPa |
| Thermal conductivity | approx. 120 W/(m·K) |
| Electrical conductivity | approx. 28 % IACS |
| Melting range | approx. 915 to 955 °C |
Fabrication and Working Practice
C26000 is excellent for cold working and fair for hot working. The recommended hot working range is 725 to 850 °C, full annealing is carried out between 425 and 650 °C, and stress relief annealing is performed at lower temperatures where dimensional stability matters. The alloy has outstanding soldering and brazing characteristics. It welds relatively well with oxy-acetylene and with resistance spot or seam welding, and it can be joined by gas shielded arc welding with appropriate procedure qualification. Machinability is moderate rather than free cutting, so the alloy is normally chosen for forming operations rather than for high-volume turning.
Supply condition: flat bar from 6 mm up to 130 mm width, lengths of 1 to 6 m or cut to order.
Surface finishes commonly offered include cold drawn, bright drawn, polished, centreless ground, hot rolled annealed and pickled, peeled and turned.
Corrosion resistance is good against atmospheric exposure and against many chemical agents.
Dezincification can occur in stagnant or slowly moving salt solutions and in acidic solutions; where this risk exists in water service, an arsenical or otherwise inhibited grade is selected instead of the plain composition.
The alloy must not be used in contact with ammonia or ammonium compounds, because it is susceptible to stress corrosion cracking in that environment.
Typical Applications
Architectural trim, grille work and decorative hardware
Drawn and spun containers, components and radiator cores
Electrical terminals, plugs, lamp fittings and nameplates
Locks, door handles and plumbers' hardware
Fasteners and cartridge-case type components
Pump cylinder liners and general engineering parts
FAQ
Q: What is the difference between C26000 and free-cutting brass?
C26000 contains very little lead, so it is chosen for forming and joining rather than for high-speed machining. Free-cutting brass, by contrast, trades ductility for a much higher machinability rating.
Q: Which standard covers C26000 flat bar?
ASTM B36/B36M covers brass plate, sheet, strip and rolled bar, and C26000 is the composition listed as cartridge brass. The order should state the standard, the alloy and the temper.
Q: Can C26000 be welded?
Yes, with care. Soldering and brazing are the preferred processes, oxy-acetylene and resistance welding work relatively well, and gas shielded arc welding is feasible with a qualified procedure.
Q: Does C26000 dezincify?
It can do so in stagnant or slowly moving salt and acidic solutions. Where that risk is present, an inhibited or arsenical grade is selected instead of the plain C26000 composition.
Q: What is the hot working temperature range?
The recommended hot working range is 725 to 850 °C, with full annealing between 425 and 650 °C and lower temperatures used for stress relief.
Q: Why is C26000 used so widely?
It offers the highest ductility of the plain brasses together with good corrosion resistance, excellent soldering and brazing behaviour, useful electrical conductivity and a bright yellow appearance.
