Introduction
This article explains C26000 cartridge brass 70/30, covering composition and applications. C26000 cartridge brass, also known as 70/30 brass, contains about 70 percent copper and 30 percent zinc. It is the most formable of the common brasses and is used for deep-drawn parts, cartridge cases, hardware, fasteners and a wide range of decorative and engineering products.
Composition
Cartridge brass is defined by a copper range of 68.5 to 71.5 percent with the balance zinc, and it may contain small limits of iron, lead and other impurities. The 70/30 ratio sits above the dezincification-prone boundary, which gives the alloy good corrosion resistance in atmospheric and fresh-water service while keeping excellent cold formability.
Properties and Cold Working
The alloy work-hardens rapidly and can be rolled, drawn, stamped and deep-drawn in many stages with intermediate annealing. It combines a tensile strength from about 300 MPa annealed up to 550 MPa in hard tempers with elongation above 50 percent in the annealed state, and it takes a bright polish that makes it a classic material for hardware and decorative fittings.
| Property | Typical Value |
|---|---|
| Copper | 68.5 - 71.5% |
| Zinc | Balance |
| Tensile strength | 300 - 550 MPa by temper |
| Elongation | Above 50% annealed |
Applications
Typical products are cartridge and shell cases, electrical terminals and connectors, fasteners, radiator cores, ammunition components, musical instruments, jewelry findings and architectural hardware. Sheet, strip, rod, wire and tube forms are all available under standards such as ASTM B36, B134, B135 and B19.
Selection and Verification
Specify the temper, dimensions and surface quality against the applicable standard, and verify the copper content, mechanical properties and hardness on the mill certificate. For deep drawing, confirm the grain size and the lubricant compatibility with the forming process.
