Introduction
C3604 brass is a copper-zinc alloy widely known as free-cutting brass — the most commonly used brass grade in automatic lathe and Swiss-type (screw machine) machining industries. As a member of the Cu-Zn alloy family, it contains 57–61% copper (Cu) and the balance in zinc (Zn), with a controlled addition of lead (Pb) to significantly enhance machinability.
Key Characteristics
- Excellent machinability — ideal for CNC turning, drilling, and milling at high speeds
- High strength — suitable for components that bear mechanical stress and load
- Good corrosion resistance — performs well against most corrosive media
- High electrical conductivity — well-suited for electrical connectors, plugs, and sockets
- Low-temperature stability — resists embrittlement in cold environments
C3604 Brass Chemical Composition
Reference standard: JIS H3250:2006 / JIS H3250:2021
| Grade | Standard | Cu (%) | Zn (%) | Pb (%) | Sn (%) | Fe (%) | Total Impurities (%) |
|---|---|---|---|---|---|---|---|
| C3604 | JIS H3250 | 57–61 | Balance | 1.8–3.7 | Fe+Sn ≤ 1.0 | ≤ 0.5 | ≤ 0.3 |
Physical Properties of C3604 Brass
| Property | Value |
|---|---|
| Density | 8.46 g/cm³ |
| Electrical Conductivity | 24 %IACS |
| Thermal Conductivity | 118 W/(m·K) |
| Thermal Expansion Coefficient | 205 μm/(m·K) |
| Specific Heat | 0.38 J/(g·K) |
| Elastic Modulus | 105 GPa |
| Condition | F (as fabricated) |
| Tensile Strength (Rm) | ≥ 335 MPa |
| Hardness | ≥ 80 HV |
Applications of C3604 Brass
C3604 brass is used across a broad range of industries due to its outstanding machinability and mechanical properties:
- Electromechanical components — electrical connectors, plugs, sockets, nuts, and screws
- Automotive parts — fuse holders, fuel injectors, horn spring contacts
- Mechanical components — bearings, gears, spline shafts
- Aerospace components — aircraft connectors, plugs, and sockets
- General hardware — electronics, hardware fittings, valve cores, and precision fasteners
Equivalent Grades to C3604
The following grades are closely equivalent to C3604 in composition and performance and may be used interchangeably where permitted:
| Grade | Standard | Cu (%) | Zn (%) | Pb (%) | Sn (%) | Fe (%) | Total Impurities (%) |
|---|---|---|---|---|---|---|---|
| HPb59-1 | GB/T 5231 | 57–60 | Balance | 0.8–1.9 | — | ≤ 0.5 | ≤ 1.0 |
| HPb59-2 | GB/T 5231 | 57–60 | Balance | 1.5–2.5 | ≤ 0.5 | ≤ 0.5 | ≤ 1.0 |
| HPb59-3 | GB/T 5231 | 57.5–59.5 | Balance | 2.0–3.0 | ≤ 0.5 | ≤ 0.5 | ≤ 1.2 |
| C3602 | JIS H3250 | 59–63 | Balance | 1.8–3.7 | Fe+Sn ≤ 1.2 | ≤ 0.5 | ≤ 0.3 |
RoHS Compliance
C3604 brass contains 1.8%–3.7% lead (Pb). However, this lead is an intentional alloying element — not a contaminant or impurity. RoHS directives include a specific exemption for lead used as an alloying element in copper, which means C3604 is fully RoHS compliant under:
- EU Directive 2002/95/EC (January 23, 2003)
- RoHS Recast Directive 2011/65/EU
For customers requiring lead-free solutions or lead content below 1,000 ppm, we also supply lead-free copper alloy alternatives. Please contact us for material specifications.
Standards reference: JIS H3250:2006, JIS H3250:2021 | GB/T 5231