Weight %. Silicon replaces lead: ~3% Si forms hard kappa and gamma phases that break the chips; low zinc with no β phase resists dezincification — no arsenic inhibitor needed.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Copper | Cu | 73.0 | 77.0 |
| Zinc | Zn | Balance | |
| Silicon | Si | 2.7 | 3.4 |
| Phosphorus | P | 0.04 | 0.15 |
| Lead (max) ✓ | Pb | — | 0.09 |
Note: ASTM/UNS C69300 caps lead at ≤0.09%, while the EN equivalent CW724R (EN 12164) allows ≤0.10% — 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.
Typical rod values by section size and cold work — strength falls as the section grows. The mill certificate reports the values of the supplied rod.
| Property | Condition | Value | Unit |
|---|---|---|---|
| Tensile / Yield (0.5 % ext.) / Elongation | rod M30 (as hot extruded), 1.5 in (38 mm) | ~517 / ~269 / ≥15 | MPa / MPa / % |
| Tensile / Yield (0.5 % ext.) / Elongation | rod H02 (half hard), 1 in (25 mm), 5 % cold work | ~607 / ~345 / ~10 | MPa / MPa / % |
| Tensile / Yield (0.5 % ext.) / Elongation | rod H02, 0.5 in (13 mm), 13 % cold work | ~724 / ~414 / ≥5 | MPa / MPa / % |
| Hardness | rod M30 1.5 in → H02 0.5 in, as above | 79 → 97 | HRB |
| Hot Forgeability | CDA rating (C37700 = 100) | 95 | index |
| Machinability | CDA rating (C36000 = 100) | 85 | index |
| Density | at 20 °C | 8.3 | g/cm³ |
| Electrical Conductivity | at 20 °C | 8 | %IACS |
| Thermal Conductivity | at 20 °C | 38 | W/(m·K) |
| Thermal Expansion | CDA, 20–100 °C | 18.5 | ×10⁻⁶/K |
| Melting Range | solidus–liquidus | 855–880 | °C |
| Modulus of Elasticity | CDA | 105 | GPa |
| Standard | Designation |
|---|---|
| UNS / ASTM (USA) | C69300 — ASTM B371 |
| EN — equivalent | CW724R / CuZn21Si3P |
| 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 |
| Chemical designation | CuZn21Si3P |
| Trade name | Lead-Free Silicon Brass |
C69300 is a lead-free silicon brass (CuZn21Si3P) with 73–77% copper, ~3% silicon, and lead held at or below 0.09%. Its hard kappa and gamma phases break the chips (about 85% machinability), low zinc and the absence of β phase make it dezincification-resistant, and it is among the strongest grades in our library — a common choice for low-lead potable-water components.
C69300 is the UNS equivalent of CW724R — both are CuZn21Si3P. The same bar stock typically certifies to either designation; we confirm the certificate wording your market requires at quotation.
The material meets NSF/ANSI 372 (weighted Pb ≤0.25%) and is dezincification resistant per ISO 6509-1, making it suitable for potable-water components in the US, Canada and the UK; in the EU the listed composition is CW724R (European positive list, entry 1658). Note that end-product approvals (NSF 61, WRAS, KTW, etc.) attach to the finished product and are held by the product maker — we machine components to your approved drawing.
Expect about 85% of the C36000 benchmark (CDA rating): slightly higher cutting forces and tool wear, but well-broken chips and excellent surface finish on sliding-head CNC machines. It is significantly harder than leaded brass, so feeds and tooling are adjusted — send your drawing for a quote within 24 hours.
Write the standard and designation together, for example “ASTM B371 – C69300”. The table above gives values by condition (half-hard); state the condition or a minimum property on the drawing when it matters. 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.
ASTM B371 – C69300. The EN equivalent is CW724R / CuZn21Si3P.Primary source: Copper Development Association C69300.
Lead-free, DZR, NSF/ANSI 372 — 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 C69300 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.