Brass C360 free cutting
Chemical composition
Section titled “Chemical composition”| Element | Content (% by weight) |
|---|---|
| Copper (Cu) | 60 – 62 |
| Lead (Pb) | 2.5 – 3.5 |
| Iron (Fe), max. | 0.3 |
| Nickel (Ni), max. | 0.3 |
| Aluminum (Al), max. | 0.05 |
| Tin (Sn), max. | 0.2 |
| Others (total), max. | 0.2 |
| Zinc (Zn) | Balance |
The typical nominal composition is 61.5% Cu, 3% Pb and 35.5% Zn. Lead appears as fine dispersed particles that promote chip breakage during machining.
Mechanical properties
Section titled “Mechanical properties”Values depend on the temper or condition supplied. The usual conditions are annealed (temper O), half-hard (H02, equivalent to R360) and hard (H04 / R400). In some cases it is also supplied in extra hard temper with higher strength.
| Temper | Tensile strength (MPa / ksi) | Yield strength 0.2% (MPa / ksi) | Elongation (%) | Brinell hardness (HB) |
|---|---|---|---|---|
| Annealed (O) | 338 / 49 | 124 / 18 | 53 | [VERIFY] |
| Half-hard (H02 / R360) | 360 / 52 | 180 / 26 | 20 | 90 |
| Hard (H04 / R400) | 400 / 58 | 250 / 36 | 12 | 120 |
| Extra hard (H06) [VERIFY] | 469 / 68 | 310 / 45 | ~8 [VERIFY] | ~140 [VERIFY] |
Higher strength values, around 469 MPa tensile and 310 MPa yield strength, are achieved in hard temper with reduced elongations. The R400 variant also shows a minimum elongation of 8% over a gauge length of 100 mm. The properties in annealed condition allow very high deformations (elongation of 53%), but with low strength. The elastic modulus is 117 GPa (17 000 ksi), the shear modulus is 37 GPa (5370 ksi), and Poisson’s ratio is 0.34.
Physical properties
Section titled “Physical properties”| Property | SI Value | Imperial Value |
|---|---|---|
| Density | 8.49 g/cm³ | 0.307 lb/in³ |
| Melting point | 885 °C | 1630 °F |
| Machinability (C360 = 100) | 100 | 100 |
Thermal properties
Section titled “Thermal properties”| Property | SI Value | Imperial Value |
|---|---|---|
| Coefficient of thermal expansion (20 – 300 °C) | 20.5 µm/(m·°C) | 11.4 µin/(in·°F) |
| Thermal conductivity at 20 °C | 115 W/(m·K) | 798 BTU·in/(hr·ft²·°F) |
Heat treatments
Section titled “Heat treatments”Brass C360 cannot be hardened by heat treatment; its strength is only increased by cold working. Full annealing is performed between 425 °C and 600 °C [VERIFY] (800 – 1100 °F) with holding and slow furnace cooling. For stress relief after machining, heating from 260 to 370 °C (500 – 700 °F) [VERIFY] and air cooling is recommended. Higher temperatures can cause zinc evaporation and surface lead loss.
Processing and fabrication
Section titled “Processing and fabrication”- Hot workability: limited. Lead causes hot shortness, so hot forging and extrusion require a narrow temperature range, typically between 730 and 790 °C [VERIFY].
- Cold workability: very limited. Not suitable for deep drawing, embossing, or severe bending. It is designed to be supplied in extruded bar and worked exclusively by chip removal.
- Casting: suitable for sand casting, permanent mold casting, and continuous casting. Cast parts are mainly used for valve assemblies and high-volume plumbing fittings.
Welding and joining
Section titled “Welding and joining”- Brazing: recommended. Brass or silver filler metals are used, with fluxes suitable for leaded brass.
- Soldering: possible with tin‑lead alloys, achieving joints with good tightness.
- Butt resistance welding: feasible with precise parameter control.
- Arc or oxyacetylene welding: not recommended. The high local temperature causes zinc vaporization and risk of hot cracking.
Machining
Section titled “Machining”The machinability of brass C360 is at the maximum reference value, with a rating of 100 on the C360 scale itself. It is the highest among all coppers and brasses, allowing very high cutting speeds and excellent chip breakage. It can be machined without cutting fluid, although a light coolant improves surface finish and extends tool life. Recommended tools are high-speed steel (HSS) or carbide.
Applications
Section titled “Applications”Brass C360 is used in sectors requiring series production using automatic lathes and machining centers, where the combination of excellent machinability and moderate mechanical strength is optimal.
- Plumbing and faucets: valve bodies, fittings, nozzles, diffusers.
- Automotive industry: air connectors, hose terminals, carburetor parts.
- Electrical and electronics: bushings, pins, turned terminals, contact supports.
- Watchmaking and precision instruments: shafts, pinions, bushings, small gears.
- General applications: special fasteners, threaded inserts, pins, locksmith components, and technical jewelry.
Comparison with similar alloys
Section titled “Comparison with similar alloys”| Property | Brass C360 (CuZn36Pb3) | Brass C353 (CuZn37Pb1) [VERIFY] | Brass C385 (CuZn39Pb3) [VERIFY] |
|---|---|---|---|
| Cu content (%) | 60 – 62 | 60 – 63 | 57 – 60 |
| Pb content (%) | 2.5 – 3.5 | 1.5 – 2.5 | 2.5 – 3.5 |
| Machinability (C360=100) | 100 | 90 | 90 |
| Tensile strength (MPa, half-hard) | 360 | 350 | 380 |
| Typical applications | High‑volume turned parts, valves, connectors | Plumbing components with lower machining demands | Architecture, hardware, and decorative profiles |
C360 stands out for its superior machinability and its balance between strength and moderate ductility. C353 is preferred when a slightly lower raw material cost is required while maintaining good machinability, while C385 is common in profiles for architectural applications.
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the machinability of brass C360 compared to other brasses?
Section titled “What is the machinability of brass C360 compared to other brasses?”The machinability of C360 is 100, the maximum reference on the scale, and exceeds that of any other brass and most copper alloys.
What is the density of brass C360?
Section titled “What is the density of brass C360?”The density is 8.49 g/cm³ (0.307 lb/in³), equivalent to a weight of about 8.49 kg per liter of material.
At what temperature does brass C360 melt?
Section titled “At what temperature does brass C360 melt?”Its melting point is around 885 °C (1630 °F), making it suitable for sand and permanent mold casting.
What is its mechanical strength in annealed condition?
Section titled “What is its mechanical strength in annealed condition?”In annealed condition, the tensile strength is approximately 338 MPa (49 ksi) and the yield strength about 124 MPa (18 ksi), with an elongation of 53%.
How much lead does brass C360 contain?
Section titled “How much lead does brass C360 contain?”The nominal lead content is 3%, with an allowable range between 2.5% and 3.5%, necessary to ensure chip fragmentation.
What is its thermal conductivity?
Section titled “What is its thermal conductivity?”The thermal conductivity at 20 °C is 115 W/(m·K) (798 BTU·in/(hr·ft²·°F)), an average value among brasses.
References
Section titled “References”- azom.com: https://www.azom.com/article.aspx?ArticleID=6391
- engineeringtoolbox.com: https://www.engineeringtoolbox.com/
- steelnumber.com: https://www.steelnumber.com/en/steel_alloy_composition_eu.php?name_id=1353