# UNS C28000 brass

Specify Muntz metal by chemistry, product standard and condition; distinguish CuZn40 supplier examples from UNS compliance and qualify forming, joining and corrosion service.

Reviewed: 2026-11-01

Tags: materials, brass, copper-alloys, c28000, muntz-metal

## Identity and purchasing scope

The CDA lists **0.09% maximum lead** for **C28000**. ALMAG's related **60/40PB CW509L** forging product permits **0.2% lead** under its **EN 12165:2024** chemistry table. The ALMAG limit alone cannot establish C28000 compliance. Compare the actual heat certificate and the ordered product requirements. [CDA wrought-brass designation table](https://datasheets.copper.org/wrought-brasses.pdf), [ALMAG CW509L forging data](https://www.almag.it/it/pdf/6040PB-CW509L-ST-EN.pdf)

**UNS C28000**, called **Muntz metal**, is a copper-zinc brass commonly described by the nominal shorthand 60/40. The Copper Development Association's designation sheet lists **Cu 59.0–63.0%, Pb maximum 0.09%, Fe maximum 0.07%, zinc remainder**, with **Cu plus the sum of named elements at least 99.7%** under footnote 2. Nominal “60/40” is not an exact chemical analysis. [CDA wrought-brass designation sheet, p. 3](https://datasheets.copper.org/wrought-brasses.pdf)

ALMAG's **60/40PB CW509L** sheet lists **59.0–61.5% copper** for the same forging product. [ALMAG hot-forging product, Rev. 11-2025](https://www.almag.it/it/pdf/6040PB-CW509L-ST-EN.pdf)

## Product condition and mechanical data

Keep mechanical properties tied to the supplied product. ALMAG's hot-forging sheet gives **430–480 MPa tensile strength**, **310–380 MPa 0.2% proof strength** and **20–30% elongation**, but explicitly marks these figures **unregulated and purely indicative**. Special hardness requirements must be defined when ordering. These values should not become guaranteed C28000 design limits. [ALMAG mechanical-property qualification, p. 3](https://www.almag.it/it/pdf/6040PB-CW509L-ST-EN.pdf)

Wieland's **Z20 CuZn40 rolled-product** sheet separately lists R340, R400 and R470 conditions. Its R340 tensile interval is **340–420 MPa** with minimum **A50mm elongation 33%**. The sheet itself prints “no UNS standard,” so this is a named supplier example rather than a C28000 acceptance table. [Wieland Z20 rolled-product sheet](https://www.wieland.com/it/content/download/9959/file/Z20_RP_EN.pdf)

For design and inspection, distinguish typical data, minimum requirements and demonstrated component performance. Preserve gauge length and proof-stress method with the test result. Confirm the row and thickness or size range that apply to the order. Do not translate a temper solely by matching a tensile number from another product form.

For a formed or joined component, determine the resulting local condition. Acceptance of incoming stock does not establish the strength of a bend, thread, hot-formed feature or joint. Identify the loads, temperatures, stress concentrations and permissible deformation that the completed part must withstand.

## Fabrication and process planning

ALMAG identifies its related CuZn40 product as an **α+β hot-forging alloy**. Use its supplier guidance within that product's scope rather than assigning one forming recipe to every C28000 item. [ALMAG product description and technological properties](https://www.almag.it/it/pdf/6040PB-CW509L-ST-EN.pdf)

Plan forming around the actual stock condition, feature geometry and required finish. Agree bend orientation, radii, heating and cooling where applicable, dimensional allowance and final inspection with the producer. A hot-forging application does not establish that an arbitrary cold bend will be acceptable. Validate crack-prone features and transitions before production quantities.

Wieland rates its Z20 cold-work capacity and machinability **fair**, soft soldering **excellent**, gas-shielded arc welding **fair**, and laser welding **less suitable**. These comparative ratings are not speeds, feeds or qualified joining procedures. [Wieland fabrication guidance](https://www.wieland.com/it/content/download/9959/file/Z20_RP_EN.pdf)

For machining, qualify tooling, chip control, workholding, burr limits and inspection on the delivered condition. Do not assume the cutting behavior of a deliberately leaded free-machining brass. For joining, specify the process, preparation, filler if used, thermal cycle and acceptance tests. Establish electrical or leak performance on the finished joint when those functions matter.

## Corrosion: distinguish the failure mechanisms

**Dezincification** removes zinc selectively and can leave a weak, porous copper-rich structure. AMPP identifies copper-zinc alloys above 15% zinc as susceptible under relevant conditions. C28000's high zinc content therefore warrants service-specific evaluation; its historical use or appearance does not establish dezincification resistance. [AMPP dezincification guidance](https://www.ampp.org/technical-research/what-is-corrosion/forms-of-corrosion/dezincification)

Specify the actual water or chemical composition, temperature, flow/stagnation, deposits, cleaning agents and exposure duration. Assess whether the application requires a tested dezincification-resistant material and a particular acceptance method. Do not infer potable-water approval, pressure-system suitability or immunity to corrosion from the designation “Muntz metal.”

Wieland warns of attack by acids, hydrous sulfur compounds and hydrous ammonia, with stress-corrosion cracking relevant to its non-stress-relieved Z20 condition. Keep atmospheric exposure separate from immersion: resistance to marine air does not establish performance in flowing or stagnant seawater. [Wieland corrosion limits](https://www.wieland.com/it/content/download/9959/file/Z20_RP_EN.pdf)

Stress-corrosion assessment must include applied and residual stress as well as environment. Define any stress-relief process and its validation with the supplier; do not assume it removes every corrosion mechanism. Reassess dimensional and mechanical requirements after thermal treatment.

## Bounded mass example and release record

Wieland lists **8.41 g/cm³** room-temperature density for its Z20 product. As an original preliminary estimate for that named material, a solid **100 × 50 × 5 mm** plate has volume **25 cm³** and mass `25 × 8.41 = 210.25 g`. This excludes tolerances, holes and coatings; it is not a universal certified density or finished C28000 part weight. [Wieland physical-property reference values](https://www.wieland.com/it/content/download/9959/file/Z20_RP_EN.pdf)

Retain material identity, lot, standard, condition, drawing revision and required chemistry/mechanical results. Record relevant forming, joining and cleaning processes, final dimensions and inspection. Compare proposed substitutions against the whole service requirement rather than color, nominal composition or one strength number.

Sources reviewed November 1, 2026. CDA's PDF states **Revision Date: May 13, 2026**. ALMAG prints **Rev. 11-2025**; Wieland prints **09.20**. AMPP's cited page has no explicit technical publication date.

## Related reference

[Grades, conditions and material selection](../grades-tempers-and-conditions.md)