COMPREHENSIVE TECHNICAL ANALYSIS AND DATASHEET OF UNS C26000 CARTRIDGE BRASS FASTENERS
UNS C26000, universally known as "Cartridge Brass" or "70/30 Brass," represents the optimal balance of reliable strength and extreme ductility within the copper-zinc alloy family. Composed of approximately 70% Copper and 30% Zinc, this single-phase alpha brass boasts the absolute highest cold-working capacity of all brasses. This exceptional formability makes it the premier metallurgical choice for complex cold-headed fasteners, solid rivets, and highly deformed machine screws that would cause lesser alloys to fracture during manufacturing.
While not designed for extreme high-load structural applications like alloy steel or Beryllium Copper, C26000 provides brilliant architectural aesthetics, reliable moderate electrical conductivity (~28% IACS), and solid resistance to general atmospheric corrosion. Its unique combination of severe formability, non-magnetic properties, and reliable fastening strength has solidified its place in electrical, decorative, and specialized commercial manufacturing.
■ Product Overview & Specifications
| Material Classification | Single-Phase Alpha Brass (70/30 Cartridge Brass) |
|---|---|
| UNS Designation | C26000 |
| Microstructure | Alpha Solid Solution |
| Magnetic State | Completely Non-Magnetic |
| Density | 8.53 g/cm³ (0.308 lb/in³) |
| Size Range | Metric: M2 to M24 | Imperial: #2 to 1" |
| Primary Attribute | Maximum Cold-Heading / Cold-Working Capacity |
■ Proprietary Datasheet Download (GATED)
UNS C26000 Cartridge Brass — Complete Technical Datasheet
Contains detailed cold-heading dimensional tolerances, upset-ratio limits for custom rivet designs, and specific torque yield limits to prevent shearing in soft brass assemblies.
⬇ DOWNLOAD DATASHEET■ MTC Integration Section
Traceability is key to ensuring the correct Copper-to-Zinc ratio. Even minor deviations can impact the alloy's ability to be cold-headed without micro-cracking. Every lot of C26000 shipped by Ananka includes fully verifiable mill documentation.
- EN 10204 Type 3.1: Validates the precise 70/30 chemical split, strict limitations on Lead and Iron impurities, and confirms the specific temper hardness generated during the cold-heading process.
- EN 10204 Type 3.2: Available upon request for critical defense or specialized marine contracts requiring third-party testing oversight.
■ Chemical Composition
The C26000 designation relies on a highly pure mix of Copper and Zinc. Notably, it contains almost zero Lead (capped at 0.07%), distinguishing it from free-machining brasses. This lack of Lead is what allows the crystalline structure to deform and flow so smoothly under extreme pressure without shearing.
| Copper (Cu) | Zinc (Zn) | Lead (Pb) | Iron (Fe) |
|---|---|---|---|
| 68.5 – 71.5 | Balance (~28.5 – 31.5) | 0.07 Max | 0.05 Max |
■ Mechanical Properties
| Mechanical Property | Typical Limits (Hard Temper / Cold Headed) |
|---|---|
| Tensile Strength | 62,000 - 75,000 psi (425 - 515 MPa) |
| Yield Strength | 45,000 - 55,000 psi (310 - 380 MPa) |
| Elongation (in 2 inches) | 10% - 20% |
| Hardness (Rockwell B) | 75 - 85 HRB |
■ Equivalent Grades & Designations
| Standard / System | Designation |
|---|---|
| ASTM Specifications | ASTM B134 (Wire), ASTM B36 (Plate/Sheet) |
| Common Trade Names | 70/30 Brass, Cartridge Brass, Spinning Brass |
| European Equivalent | EN CW505L / CuZn30 (DIN 2.0265) |
| British Standard (BS) | CZ106 |
■ Applications & Industries
- Electrical & Switchgear Components: Non-magnetic binding head screws, terminal posts, and relay assembly fasteners requiring decent conductivity and high ductility.
- Architectural & Decorative Hardware: Hinges, door handles, and visible aesthetic fasteners that require a bright, golden finish or specialized antique patinas.
- Automotive & Plumbing: Hose clamps, radiator cores, and non-corrosive fluid handling hardware where moderate strength and easy forming are required.
■ Compatible Fastener Assemblies
| Mating Bolts/Machine Screws | Internal Threads (Nuts) | Washers |
|---|---|---|
| C26000 Cold Headed Machine Screws | C26000 / C27000 Hex Nuts | C26000 Solid Brass Flat Washers |
■ Torque & Installation Guidelines
Brass is relatively soft compared to carbon and alloy steels. Applying standard steel installation torque will rapidly strip the threads or stretch the bolt beyond its yield point. Tightening must be carefully managed, particularly for smaller diameter machine screws.
| Nominal Diameter | Threads Per Inch (UNC) | Max Target Torque (in-lbs) | Max Target Torque (ft-lbs) |
|---|---|---|---|
| #10 | 24 | 35 - 40 | ~ 3 |
| 1/4" | 20 | 65 - 75 | ~ 6 |
| 5/16" | 18 | 120 - 130 | ~ 10 |
| 3/8" | 16 | 200 - 220 | ~ 17.5 |
■ Frequently Asked Questions
1. Why is this specific alloy called "Cartridge" Brass?
The name originates from its historical and ongoing use in military ammunition casings (cartridges). Manufacturing a bullet casing requires "deep drawing"—taking a flat disc of metal and violently punching it into a long cylinder. Only a 70/30 copper-zinc mixture possesses the extreme ductility required to withstand this deep drawing process without cracking or tearing. Fastener manufacturing exploits this same ductility for aggressive cold-heading.
2. Is C26000 considered a "Free-Machining" Brass?
No. In fact, C26000 is notoriously difficult to machine. Because it is so highly ductile, the metal tends to stretch, gum up, and wrap around cutting tools rather than breaking off into clean chips. If highly complex, turned fasteners are required (created on a CNC lathe rather than cold-headed), a free-machining alloy like UNS C36000 (which contains Lead to break the chips) is vastly superior.
3. Can C26000 fasteners suffer from "Dezincification"?
Yes. In certain aggressive environments—specifically polluted water, stagnant seawater, or areas with high ammonia concentrations—the zinc within the 70/30 matrix can leach out, leaving behind a porous, fragile copper shell. For critical underwater marine applications, Naval Brass (which adds Tin to prevent this) or Silicon Bronze should be specified instead of Cartridge Brass.