Beta Brass is a high-zinc brass alloy containing more than 45% zinc, resulting in a body-centered cubic (BCC) β-phase crystal structure. This makes beta brass significantly harder and stronger, but less ductile, than alpha and alpha–beta brasses.
Typical compositions include Cu–50%Zn and Cu–55%Zn, often alloyed with small additions of aluminum, manganese, or tin to enhance strength, wear resistance, and corrosion behavior.
Classification & Metallurgical Note
Phase: Single-phase β or ordered β′
Typical Zn content: 45 – 50%
Crystal structure: BCC (β) → ordered B2 (β′) on cooling
Important: On cooling, β transforms to ordered β′, which increases hardness and brittleness.
Typical Chemical Composition
| Element | Typical % | Metallurgical Role |
|---|---|---|
| Copper (Cu) | 50 – 55 | Base metal, corrosion resistance |
| Zinc (Zn) | 45 – 50 | Strength, hardness, β-phase formation |
| Aluminum (Al) | 0 – 2.0 | β-phase stabilization, oxidation resistance |
| Manganese (Mn) | 0 – 2.0 | Strength, grain refinement |
| Iron (Fe) | 0 – 1.0 | Hardness, fatigue resistance |
| Lead (Pb) | ≤ 0.2 | Machinability |
| Others | Trace | Controlled impurities |
Physical Properties
| Property | Typical Value |
|---|---|
| Density | 8.0 – 8.3 g/cm³ |
| Melting Range | 860 – 900 °C |
| Electrical Conductivity | 8 – 15% IACS |
| Thermal Conductivity | 80 – 100 W/m·K |
| Thermal Expansion | ~20 µm/m·°C |
| Magnetic Property | Non-magnetic |
| Color | Pale yellow to whitish-gold |
Mechanical Properties
| Property | Typical Range |
|---|---|
| Tensile Strength | 650 – 900 MPa |
| Yield Strength | 400 – 650 MPa |
| Elongation | 3 – 10% |
| Hardness | 200 – 280 HV |
| Modulus of Elasticity | 95 – 100 GPa |
| Wear Resistance | Very High |
Metallurgical Behavior
At high temperature, disordered β-phase is relatively ductile and suitable for hot working. On cooling, ordering to β′ increases strength but severely reduces ductility.
Beta brass is not precipitation-hardenable and has very limited cold workability before fracture.
Processing Characteristics
Casting: Excellent
Hot forging & extrusion: Excellent
Cold working: Poor
Machining: Fair
Welding: Difficult
Brazing & soldering: Good
Available Forms
Castings
Forgings
Extruded bars and rods
Heavy plates
Custom-shaped sections
Not suitable for:
Thin sheet, wire, or deep-drawn products
Applications
Heavy gears and worm wheels
Wear plates and heavy bushings
Marine pump and valve components
Non-sparking tools for defense and safety
Mining and construction abrasion-resistant parts
Advantages
✔ Highest strength among brass alloys
✔ Exceptional wear and abrasion resistance
✔ Excellent hot workability
✔ Cost-effective alternative to bronze
✔ Suitable for thick, heavy sections
Why Choose Beta Brass?
Beta brass is selected when maximum strength, hardness, and wear resistance are required, and cold ductility is not critical. It represents the upper strength limit of the brass family and provides a durable, cost-effective solution for heavy-duty engineering applications.
Quick Comparison
| Alloy | Strength | Ductility | Hot Workability |
|---|---|---|---|
| Cartridge Brass (α) | Medium | Excellent | Good |
| Muntz Brass (α+β) | High | Moderate | Excellent |
| Manganese Brass | Very High | Moderate | Excellent |
| Beta Brass (β) | Extreme | Low | Excellent |