AZ31B is a wrought magnesium composed of aluminum, zinc, manganese, silicon, copper, calcium, iron, nickel, and magnesium. Often used as a tooling plate, the combination of the listed alloys gives AZ31B good strength and ductility along with weldability, corrosion resistance, and a high strength-to-weight ratio while also being lightweight. It is important to note that this magnesium grade is flammable, which impacts how machinability should be monitored.
Due to AZ31B magnesium’s properties, it is commonly used in aerospace and general commercial applications, specifically cell phones, aircraft fuselages, laptop cases, and speaker cones on top of its tooling plate uses.
| Property | Value | Notes |
|---|---|---|
| Material Type | Magnesium Alloy | ASTM B90/B90M; AZ = Aluminum/Zinc alloyed |
| Density | 1.78 g/cm³ | 0.064 lb/in³ — ~35% lighter than aluminum |
| Melting Point | ~595–635°C | ~1,100–1,175°F |
| Hardness (Brinell) | ~65 HB | Relatively soft metal |
| Tensile Strength | ~275 MPa | ~40,000 psi |
| Yield Strength | ~200 MPa | ~29,000 psi |
| Elongation at Break | ~10–20% | Moderate ductility |
| Modulus of Elasticity | ~45 GPa | ~6.5 x 10⁶ psi — much lower than aluminum or steel |
| Corrosion Resistance | Fair (with coating) | Poor in saltwater; needs anodizing or painting for protection |
| Magnetism | Non-magnetic | Useful in electronics and aerospace |
| Heat Treatment | Limited (non-heat-treatable) | Typically strain hardened and annealed |
| Machinability | Excellent | Chips easily; low cutting forces required |
| Weldability | Good (in thin sections) | Best with TIG; can be difficult in thicker material |
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