Weight %. Silicon replaces lead: the hard kappa and gamma phases break the chips, and the low zinc content with no β phase resists dezincification without an arsenic inhibitor.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Copper | Cu | 75.0 | 77.0 |
| Zinc | Zn | Balance | |
| Silicon ✓ | Si | 2.7 | 3.5 |
| Phosphorus | P | 0.02 | 0.10 |
| Lead (max) ✓ | Pb | — | 0.10 |
Note: EN 12164 caps CW724R lead at ≤0.10%, while the ASTM/UNS equivalent C69300 caps it at ≤0.09% — a genuine (small) difference between the two standards, not an inconsistency.
Bars show the range from the table: bar length at mid-range, zinc as the remainder.
EN 12164 condition values (minimum values). Condition names give the minimum tensile strength; hardness conditions (H…) are an alternative way to order. The EN 10204 3.1 certificate reports the values of the supplied bar. Physical properties are typical values; a range shows the spread of published data (reference: Copper Development Association, UNS equivalent C69300).
| Property | Condition | Value | Unit |
|---|---|---|---|
| Condition M | as manufactured | no limits | — |
| Tensile / 0.2 % Proof / Elongation | R500, Ø6–80 mm (proof stress is a maximum) | ≥500 / ≤450 / ≥15 | MPa / MPa / % |
| Tensile / 0.2 % Proof / Elongation | R600, Ø10–40 mm | ≥600 / ≥300 / ≥12 | MPa / MPa / % |
| Tensile / 0.2 % Proof / Elongation | R670, Ø2–20 mm | ≥670 / ≥400 / ≥10 | MPa / MPa / % |
| Hardness | hardness conditions H130 / H150 / H170 | 130–180 / 150–220 / ≥170 | HB |
| Density | at 20 °C | 8.28–8.3 | g/cm³ |
| Melting Range | solidus–liquidus | 855–930 | °C |
| Thermal Conductivity | at 20 °C | 35–38 | W/(m·K) |
| Electrical Conductivity | at 20 °C | 8 | %IACS |
| Thermal Expansion | from 20 °C (18.5 for 20–100 °C) | 18.5–20 | ×10⁻⁶/K |
| Modulus of Elasticity | at 20 °C | 100–105 | GPa |
| Machinability | CDA rating of its UNS equivalent C69300 (C36000 = 100) | 85 | index |
| Standard | Designation |
|---|---|
| EN (Europe) | CW724R / CuZn21Si3P |
| UNS / ASTM (USA) | C69300 — ASTM B371 |
| Lead-free bismuth alt. | C6802 — bismuth brass |
| Tin-bearing sibling | C69310 — JIS C6931 (Sn 0.30–0.7) |
| Lower-copper lead-free grade | C68370 / CW726R — about 1 % silicon, not listed as dezincification-resistant |
| DIN (Germany) | CuZn21Si3P |
| DZR test method | ISO 6509-1 (CuCl₂) |
CW724R (CuZn21Si3P) replaces lead with silicon: the hard kappa phase breaks chips during machining, giving around 85% machinability — high for a lead-free grade — while keeping lead at or below 0.10%. It is fully RoHS compliant without relying on Exemption 6(c).
Yes — intrinsically. With only ~21% zinc and the silicon-stabilised microstructure, CW724R resists dezincification without arsenic additions, which is why it is widely specified for potable water fittings in both soft and chloride-rich supplies.
With lead ≤0.10%, CW724R satisfies the US NSF/ANSI 372 weighted-average limit of 0.25% for wetted surfaces; in the EU, CW724R is on the European positive list of metallic compositions (EUPL 1658, product groups B–D; Decision (EU) 2024/367). Final product approval (NSF 61, WRAS, ACS, KIWA) is granted to the finished fitting, which the buyer or assembler must list.
Plan for lower cutting speeds and feeds than for free-machining leaded brass (its CDA machinability rating is about 85%), sharper tooling, and closer attention to chip evacuation. Brassland machines CW724R routinely on both fixed-head and Swiss lathes — equivalents are C69300 (US) and other EN 12164 silicon brass listings.
Write the standard and designation together, for example “EN 12164 – CW724R / CuZn21Si3P – R500”. State it whenever a minimum tensile strength or hardness matters — the table above lists the values per temper (R500, R600, R670). Tolerances follow ISO 2768-m unless the title block says otherwise.
The mill’s EN 10204 Type 3.1 inspection certificate for the alloy lot reports the measured chemical composition and mechanical test results. Brassland adds a Certificate of Conformity for the order and RoHS and REACH declarations at no charge; PPAP Level 1–3 packages are available for OEM qualification.
EN 12164 – CW724R / CuZn21Si3P – R500. The UNS equivalent is C69300 — ASTM B371.Primary source: Copper Development Association — C69300 (UNS equivalent).
Lead-free, DZR, no exemption required. ISO 9001:2015. Quote within 24 hours.
Request a QuoteComposition ranges, mechanical properties, machinability ratings and regulatory data on this page are cross-referenced against the publishers below. Tolerances and minimum values are taken from the relevant published standard at the time of writing — for procurement specification, always reference the current published edition.
Last reviewed: September 2026. EN/ISO/ASTM standards are updated periodically. This datasheet reflects the editions listed; for safety-critical or contract-critical applications, always verify against the current published edition of the standard. For project-specific deviations or supplier-specific composition windows, request a Type 3.1 mill certificate (EN 10204) with your order.
Brassland machines CW724R into brass turned parts and CNC machined components to your drawing in Jamnagar, India, including precision turned brass components on 28+ Swiss-type lathes, with an EN 10204 3.1 certificate on every shipment.