What Is C26000 Cartridge Brass?
C26000 - commonly called "70/30 cartridge brass", "260 brass" or "CuZn30" - is a wrought copper-zinc alloy containing approximately 70% copper and 30% zinc. It belongs to the yellow brass family of the UNS C20000 series and is one of the most widely specified brasses in the world for cold-formed components.
The "70/30" ratio gives the alloy its unique balance of properties: the high copper content preserves good corrosion resistance and 28% IACS electrical conductivity, while the 30% zinc addition raises strength and springiness well beyond pure copper without sacrificing the deep-drawing ability that makes the alloy the industry standard for ammunition cartridge cases. It work-hardens rapidly and is normally supplied either in annealed (OS) tempers for deep drawing, or in cold-rolled (H) tempers where higher strength is required.
Chemical Composition
The registered composition of C26000 per the CDA (Copper Development Association) alloy database is shown below. Nominal composition is 70% Cu / 30% Zn.
| Element | Min / Max (%) | Nominal (%) | Note |
|---|---|---|---|
| Copper (Cu) | 68.5 – 71.5 | 70.0 | Balance basis; Cu + named elements ≥ 99.7% |
| Lead (Pb) | 0.07 max | - | Residual impurity |
| Iron (Fe) | 0.05 max | - | Residual impurity |
| Zinc (Zn) | Remainder | 30.0 | Primary alloying element |
Source: CDA alloy database, alloy C26000 (copper.org).
Physical Properties
| Product Property | US Customary | Metric |
|---|---|---|
| Coefficient of Thermal Expansion | 11.1 × 10⁻⁶ per °F (68–572 °F) | 20.0 × 10⁻⁶ per °C (20–300 °C) |
| Density | 0.308 lb/in³ @ 68 °F | 8.53 g/cm³ @ 20 °C |
| Electrical Conductivity | 28 %IACS @ 68 °F | 0.164 MegaSiemens/cm @ 20 °C |
| Electrical Resistivity | 37.0 Ω·cmil/ft @ 68 °F | 6.15 µΩ·cm @ 20 °C |
| Melting Point - Liquidus | 1750 °F | 954 °C |
| Melting Point - Solidus | 1680 °F | 916 °C |
| Modulus of Elasticity in Tension | 16,000 ksi | 110,000 MPa (110 GPa) |
| Modulus of Rigidity | 6,000 ksi | 41,370 MPa (41.4 GPa) |
| Specific Gravity | 8.53 | 8.53 |
| Specific Heat Capacity | 0.09 Btu/lb/°F @ 68 °F | 377.1 J/(kg·K) at 293 K |
| Thermal Conductivity | 70.0 Btu·ft/(hr·ft²·°F) @ 68 °F | 121.2 W/(m·K) at 20 °C |
Mechanical Properties (Typical, by Temper)
Mechanical properties of C26000 depend strongly on temper. Representative CDA typical values:
| Form / Temper | Tensile Strength (ksi / MPa) | Yield Strength 0.5% Ext (ksi / MPa) | Elongation (%) | Hardness |
|---|---|---|---|---|
| Sheet, OS070 (annealed, 0.070 mm grain) | 46 / 317 | 14 / 97 | 65 | 58 HRF |
| Sheet, OS025 (annealed, 0.025 mm grain) | 51 / 352 | 19 / 131 | 55 | 72 HRF |
| Sheet, H02 (half hard) | 62 / 427 | - | 25 | 70 HRB |
| Sheet, H04 (hard) | 76 / 524 | 63 / 434 | 8 | 82 HRB |
| Sheet, H06 (extra hard) | 86 / 593 | 65 / 448 | 5 | 88 HRB |
| Rod, OS050 (annealed, 1 in) | 48 / 331 | 16 / 110 | 65 | 65 HRF |
| Rod, H02 (half hard, 1 in) | 70 / 483 | - | 30 | 80 HRB |
| Wire, H06 (extra hard, 0.08 in) | 124 / 855 | - | 4 | - |
Source: CDA typical values for flat products (0.04 in), rod (1 in) and wire (0.08 in), copper.org alloy C26000. Values are typical, not specification minimums.
Temper Designations
| Product Type | Available Tempers |
|---|---|
| Bar, rolled | H02, OS070, OS100 |
| Sheet | H01, H02, OS035, OS050, OS070 |
| Strip, rolled | H01, H02, H04, H06, H08, H10, OS015, OS025, OS035, OS050, OS070, OS100 |
| Wire, drawn / rolled | H02, OS050 / H02, H04, H06, OS035, OS050, OS070, OS100 |
| Shapes | M30 |
| Tube | H58, H80, OS025, OS050 |
| Wire | H00, H01, H06, H08, OS015, OS025, OS035, OS050 |
Annealing range for C26000 is 800–1400 °F (427–760 °C); hot working range 1350–1550 °F (732–843 °C) per CDA.
Fabrication and Joining
| Technique | Suitability | Technique | Suitability |
|---|---|---|---|
| Soldering | Excellent | Gas Shielded Arc Welding | Good |
| Brazing | Excellent | Oxyacetylene Welding | Good |
| Capacity for Cold Working | Excellent | Coated Metal Arc Welding | Not Recommended |
| Butt Weld | Good | Spot Weld | Fair |
| Capacity for Hot Forming | Fair | Seam Weld | Not Recommended |
| Machinability Rating | 30 (free-cutting brass C36000 = 100) | ||
Typical Applications
Because of its outstanding deep-drawing behavior, corrosion resistance and stable spring properties, C26000 is specified across many industries:
Ordnance & ammunition: cartridge cases and cups (MIL-C-10375, ASTM B129), ammunition mechanical housings - the alloy's original military application.
Automotive: radiator cores, radiator tubes and tanks, heater cores, thermostats, electrical connectors, odometer contacts.
Fasteners: rivets, eyelets, grommets, pins, screws and other cold-headed fasteners.
Electrical: terminal connectors, lamp fixtures, reflectors, screw shells, flashlight shells.
Consumer goods: snaps, buttons, watch parts, pen/pencil clips and inserts, costume jewelry, bird cages, etched articles, coinage.
Industrial: heat exchangers, springs and bead chain, tubing for instruments and machines, pump cylinders, wire screens, air-pressure conveyor systems.
Builders hardware & plumbing: door hardware, fittings, faucet escutcheons, traps, plumbing brass goods.
Architecture & other: grillwork, stencils, washers.
Applicable Specifications
| End Product | Specification |
|---|---|
| Bar | ASTM B36/B36M, B19, SAE J463, J461 |
| Brazing filler metal | Federal QQ-B-650 |
| Cups, cartridge case | ASTM B129, Military MIL-C-10375 |
| Disk | ASTM B19 |
| Plate | AMS 4507, 4505; ASTM B19, B36 |
| Rod | SAE J463, J461 |
| Sheet | AMS 4507, 5408, 4505; ASTM B19, B36; SAE J463, J461 |
| Shim stock, laminated | Military MIL-S-22499 |
| Strip | AMS 4507, 4505; ASTM B36, B569, B19, B888; SAE J463, J461 |
| Tube, seamless | ASTM B135/B135M; Federal WW-T-791; Military MIL-T-20219; SAE J463, J461 |
| Tube, welded | ASTM B587 |
| Wire | ASTM B134/B134M; SAE J463, J461 |
Our factory
Our factory specializes in the production and manufacturing of high-quality copper products. We operate a comprehensive, end-to-end production line equipped with advanced continuous casting and rolling mills, precision drawing machines, high-speed rolling mills, and automated heat treatment systems. We professionally produce a wide range of copper tubes, plates, bars, wires, and foils. A strict quality inspection system is implemented throughout the entire process, from raw material intake to finished product delivery. Supported by precision instruments such as spectrometers, metallographic microscopes, tensile testing machines, eddy current flaw detectors, and laser dimension gauges, we ensure that our products fully comply with international and domestic standards-including ASTM, EN, JIS, and GB-in terms of chemical composition, mechanical properties, dimensional accuracy, and surface quality. We are committed to providing global customers with stable, reliable, and fully-specified copper material solutions.
copper product packaging
Our products are packaged using professional, customized industrial packaging solutions to ensure they remain intact during long-distance transportation and multiple handlings. For long products such as copper tubes and bars, we use sturdy waterproof wooden crates or metal-frame boxes for secure fixing and protection. Copper plates and foils are individually wrapped with anti-rust paper, then packed into steel-edged boxes or on pallets with reinforced hard corners. Copper wires are wound with moisture-proof film and neatly coiled onto custom-designed reels or placed in wooden cases. All packaging is clearly marked according to customer requirements with shipping marks, specifications, batch numbers, and handling symbols. Desiccants can also be placed inside the packages when needed, providing complete protection against rust, moisture, and impact throughout the entire journey from production to the destination port.
FAQ
Q1: What is C26000 cartridge brass?
C26000, also called 70/30 cartridge brass or CuZn30, is a wrought copper-zinc alloy containing 68.5–71.5% copper, up to 0.07% lead and 0.05% iron, with the balance zinc. It is the benchmark deep-drawing brass used for ammunition cartridge cases, radiator components, fasteners and electrical connectors.
Q2: What are the mechanical properties of C26000 brass?
Typical values vary with temper: annealed sheet (OS070) shows about 46 ksi (317 MPa) tensile strength with 65% elongation, while hard-rolled sheet (H04) reaches about 76 ksi (524 MPa) with 8% elongation (CDA typical data).
Q3: Is C26000 the same as C260 or CuZn30?
Yes. C26000 is the UNS designation; the same alloy is commonly called C260, 260 brass, 70/30 brass, cartridge brass, or CuZn30 (EN 12163 / GB/T 5231 terminology).
Q4: What is C26000 brass used for?
Typical uses include ammunition cartridge cases and cups, radiator cores and tanks, fasteners (rivets, eyelets, screws), electrical terminal connectors and lamp fixtures, clock and watch parts, plumbing fittings and hardware, and architectural grillwork.
Q5: Does GNEE supply C26000 in sheet, strip, rod and wire?
Yes. GNEE Metal Group supplies C26000 cartridge brass in sheet, strip, plate, rod, wire and tube, in annealed (OS) and hard (H01–H10) tempers, with mill test certificates and third-party inspection (SGS/BV) available on request.
