Here’s a professional comparison of the magnesium alloys AZ31B, AZ91D, and AZ80:
Material Classification & Composition (wt.%)
| Alloy | ASTM Standard | Al | Zn | Mn | Mg | Key Characteristics |
|---|---|---|---|---|---|---|
| AZ31B | B90/B107 | 3.0 | 1.0 | 0.2 | Bal. | Best formability |
| AZ91D | B94/B275 | 9.0 | 0.7 | 0.13 | Bal. | Best castability |
| AZ80 | B107 | 8.5 | 0.5 | 0.12 | Bal. | Highest strength |
Mechanical Properties
| Property | AZ31B | AZ91D | AZ80 |
|---|---|---|---|
| Tensile Strength (MPa) | 255 | 230 | 380 |
| Yield Strength (MPa) | 200 | 160 | 275 |
| Elongation (%) | 15 | 3 | 7 |
| Hardness (HB) | 55 | 65 | 85 |
| Fatigue Limit (MPa) | 110 | 90 | 150 |
| Elastic Modulus (GPa) | 45 | 45 | 45 |
Physical Properties
| Property | AZ31B | AZ91D | AZ80 |
|---|---|---|---|
| Density (g/cm³) | 1.77 | 1.81 | 1.80 |
| Melting Range (°C) | 605-630 | 595-610 | 600-620 |
| Thermal Conductivity (W/m·K) | 96 | 72 | 84 |
| CTE (10⁻⁶/K) | 26 | 26 | 26 |
Key Performance Features
AZ31B:
✓ Best weldability and formability
✓ Good corrosion resistance
✓ Suitable for sheet metal applications
AZ91D:
✓ Excellent die-casting performance
✓ Good surface finish
✓ Economical for high-volume production
AZ80:
✓ Highest strength in AZ series
✓ Can be heat treated (T5 temper)
✓ Preferred for aerospace applications
Processing Characteristics
| Process | AZ31B | AZ91D | AZ80 |
|---|---|---|---|
| Casting | Poor | Excellent | Fair |
| Extrusion | Good | Fair | Good |
| Rolling | Excellent | Poor | Fair |
| Machining | Good | Excellent | Good |
| Welding | Excellent (TIG) | Poor | Fair |
Typical Applications
AZ31B:
- Laptop/phone casings
- Automotive interior panels
- Bicycle frames
AZ91D:
- Automotive transmission cases
- Power tool housings
- Camera bodies
AZ80:
- Aircraft landing gear components
- High-performance automotive parts
- Military equipment housings
Corrosion Resistance
- General: AZ31B > AZ80 > AZ91D
- Salt Spray Test:
- AZ31B: 0.25 mm/year
- AZ91D: 0.50 mm/year
- AZ80: 0.35 mm/year
- All require surface protection (anodizing/chromating) for harsh environments
Material Selection Guide
- For forming/welding: Choose AZ31B
- For die-casting: Choose AZ91D
- For high-strength: Choose AZ80
- Cost Ranking: AZ91D < AZ31B < AZ80
Special Notes
All AZ-series alloys are flammable above 450°C (require special fire precautions)
AZ91D shows “die-casting porosity” in thick sections
AZ80 responds well to aging treatment (T5 temper increases strength by 15-20%)
All alloys are being replaced by rare-earth containing alloys (e.g., WE43) for high-temperature applications
Note: All data based on standard temper conditions (F for as-cast, T5 for aged, H24 for strain-hardened).
Great, Together
