Introduction
This article explains the chemical composition of C28000 brass. C28000 Muntz metal is a 60/40 copper-zinc alloy with a copper range of 59.0 to 63.0 percent. It is the classic hot-working brass, used for condenser plates, architectural sections, valve stems, heat exchanger components and brazing applications where the higher zinc content lowers cost.
Composition and Phase Structure
At the 60/40 composition the alloy contains both alpha and beta phases. The beta phase is harder and makes the material behave well at hot-working temperatures, so Muntz metal is easily extruded, forged, rolled and hot-formed. The two-phase structure also raises strength compared with single-phase 70/30 brass.
Properties and Limits
Muntz metal offers tensile strengths from about 340 MPa annealed to over 450 MPa in worked tempers, with moderate ductility. Because the zinc content is high, the alloy is less resistant to dezincification than cartridge brass in aggressive chloride environments, so it is best suited to atmospheric, fresh-water and sheltered industrial service rather than continuous seawater immersion.
| Property | Typical Value |
|---|---|
| Copper | 59.0 - 63.0% |
| Zinc | Balance |
| Tensile strength | 340 - 450+ MPa by temper |
| Structure | Alpha + beta phases |
Applications
Typical uses are condenser and heat exchanger plates, architectural panels and sections, valve stems, pump components, marine hardware in atmospheric service, hot forgings and brazing rod. The alloy is covered by standards such as ASTM B21, B111 and B135.
Selection and Verification
Confirm the copper range, temper and form against the standard, and verify the mechanical properties on the mill certificate. For hot working, specify the fabrication route so the supplier can supply the correct temper and grain structure.
