Mass %, JIS H3250 Table 2. The standard limits only the sum of iron and tin; zinc is the remainder and may include unanalysed elements other than Zn. Typical column = nominal analysis (58.7 Cu – 2 Pb – Zn).
| Element | Symbol | Min % | Max % | Typical % |
|---|---|---|---|---|
| Copper | Cu | 57.0 | 61.0 | ~58.7 |
| Zinc | Zn | Balance | ~39 | |
| Lead | Pb | 1.0 | 2.5 | ~2.0 |
| Iron + Tin (sum) | Fe + Sn | — | 1.0 | — |
| Property | Condition | Value | Unit |
|---|---|---|---|
| Tensile Strength | F — BE-F ≥6 mm, BD-F ≥4 mm, BF-F ≥100 mm | ≥315 | N/mm² (MPa) |
| Elongation | F — same product forms | ≥15 | % |
| Hardness | flare-nut rod C3771 BDN-SR (stress-relieved, A/F 17–36 mm) | 70–120 | HV |
| Density | typical | ~8.45 | g/cm³ |
| Electrical Conductivity | typical, 20 °C | ~27 | %IACS |
| Thermal Expansion | typical, 20–300 °C | ~21 | ×10⁻⁶/K |
| Modulus of Elasticity | typical | ~98 | GPa |
| Machinability | forging brass — as C37700 (80, CDA) and CW617N (90) | 80–90 | CW614N = 100 |
Summarised from JIS H3250:2015, with the clause or table for each row. For contract use, read the current edition of the standard.
| Requirement | What the standard says | Clause |
|---|---|---|
| Product forms | Extruded rod C3771 BE (≥6 mm), drawn rod BD (≥4 mm), forged rod BF (≥100 mm); hexagon flare-nut rod BDN-SR. | Tables 1, 4, 5 |
| Condition | F — as manufactured; SR — stress-relieved after drawing (flare-nut rod only). | Tables 4, 5 |
| Acceptance, condition F | Tensile strength ≥315 N/mm² and elongation ≥15 %. | Table 4 |
| Flare-nut rod | C3771 BDN-SR for JIS B 8607 type 1 and type 2 flare nuts: across flats 17, 22, 24, 26, 27, 29 and 36 mm; ≥315 N/mm², ≥15 %, 70–120 HV. | Table 1 note c, Table 5 |
| Season cracking | Drawn rod (not O temper, not flare-nut rod) must show no cracks after the ammonia test: a test piece of at least 75 mm is held 50–100 mm above ammonia solution of at least 11.8 % in a desiccator for at least 2 h at room temperature, pickled at once in sulfuric acid of at least 10 % and inspected by eye — round bar up to 25 mm may instead be bent about 15° over an inner radius of twice its diameter. Test frequency is at the mill’s discretion (clause 8). | 5.5, 7.5 |
| Dezincification | No requirement for C3771. JIS H3250 sets dezincification tests only for C3531 and the lead-free RD grades — for example the immersion test of Annex A, maximum dezincification depth ≤200 µm. | 5.7, Table 9 |
| Diameter tolerance | Normal grade, or special grade for drawn rod, marked with an S after BD (BDS). | Table 1 note b, Table 10 |
| Marking | Standard number and product symbol on each package, bundle or piece — for example JIS H 3250 C 3771 BD-F — plus the size, for example φ10 × 2 000 mm. | Clause 9 |
| Standard | Designation |
|---|---|
| JIS (Japan) | C3771 — JIS H3250 (BE / BD / BF rod; BDN-SR flare-nut rod) |
| EN — nearest | CW617N / CuZn40Pb2 (Cu 57–59, Pb 1.6–2.2) |
| EN — nearest | CW612N / CuZn39Pb2 (Cu 59–60, Pb 1.6–2.5) |
| UNS / ASTM — nearest | C37700 — ASTM B283 / B124 (Cu 58–61, Pb 1.5–2.5) |
| GOST (Russia) — overlapping | ЛС59-1 (Cu 57–60, Pb 0.8–1.9) |
| JIS sibling | C3604 free-cutting brass (Pb 1.8–3.7) |
C3771 is the forging brass of JIS H3250, the Japanese standard for copper-alloy rods and bars: 57.0–61.0 % copper, 1.0–2.5 % lead, iron plus tin limited to 1.0 %, balance zinc. Rod in the as-manufactured condition (F) must reach 315 N/mm² tensile strength and 15 % elongation. Its typical uses are valves and machine parts, and a stress-relieved hexagon version is made for flare nuts.
No — they overlap without matching. CW617N (CuZn40Pb2) is 57–59 % copper with 1.6–2.2 % lead, CW612N is 59–60 % copper, and C37700 is 58–61 % copper with 1.5–2.5 % lead; C3771 allows 57–61 % copper and 1.0–2.5 % lead. A C3771 heat can therefore fall inside or outside an EN or UNS grade. When a drawing names one grade and the mill supplies another, the EN 10204 3.1 analysis is compared with the limits of the specified grade before the order is confirmed.
Both are JIS H3250 leaded brasses with 57.0–61.0 % copper. C3604 is the free-cutting grade (1.8–3.7 % lead, iron up to 0.50 %) used for bolts, nuts, small screws, spindles and similar machined parts; C3771 is the forging brass (1.0–2.5 % lead) listed for valves and machine parts. In condition F, C3604 rod must reach 335 N/mm² or 80 HV, C3771 rod 315 N/mm² with 15 % elongation.
Extruded rod (C3771 BE-F, 6 mm and above), drawn rod (C3771 BD-F, 4 mm and above) and forged rod (C3771 BF-F, 100 mm and above), all in the as-manufactured condition F. For flare nuts to JIS B 8607 there is a hexagon rod, C3771 BDN-SR, stress-relieved after drawing and made in across-flats sizes from 17 to 36 mm with 315 N/mm², 15 % elongation and 70–120 HV. Dezincification-resistant (RD) variants exist in JIS H3250 only for the lead-free grades, not for C3771.
For RoHS the lead content of 1.0–2.5 % is covered by Annex III exemption 6(c), which allows up to 4 % lead in copper alloys and is currently valid to 30 June 2027. For drinking-water contact C3771 is not suitable: NSF/ANSI 372 limits the weighted lead content of wetted surfaces to 0.25 %. The lead-free JIS alternatives are the bismuth grades C6801–C6804 and the silicon brass C6932 (C69300 / CW724R).
Yes — made to your drawing. Whether stock certified to JIS H3250 C3771 is available for your quantity is confirmed at quotation; hot forging is done through our qualified forging partners, finish machining and inspection in-house. If your drawing allows an equivalent, we quote the overlapping EN or UNS grade with both analyses side by side. Series lead time is 3–5 weeks from the approved drawing, forged first articles 8–10 weeks.
JIS H 3250 C 3771 BD-F (drawn rod, as manufactured) or C 3771 BF-F for forging stock. The nearest EN grades are CW617N / CW612N (EN 12165 / EN 12164), the nearest UNS grade C37700 (ASTM B283 / B124).Primary source: JIS H3250 — Copper and copper alloy rods and bars (JISC).
Hot-forged blanks, finish-machined and inspected in Jamnagar. ISO 9001:2015. Quote within 24 hours.
Request a QuoteComposition limits, minimum properties and test requirements are taken from JIS H3250; typical values are given for orientation. For procurement specification, always reference the current published edition of the standard.
Last reviewed: September 2026. The composition and property limits shown are those tabulated in JIS H3250:2015; JIS H3250 was revised in 2021 — for safety-critical or contract-critical applications, verify against the current published edition. Typical values are not specification limits. For project-specific deviations or supplier-specific composition windows, request a Type 3.1 mill certificate (EN 10204) with your order.
Brassland machines C3771 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.