AZ91D Magnesium Alloy: High-Pressure Die Casting Grade
ASTM B94 · Published: 2026-06-01 · Updated: 2026-06-02
AZ91D is the most widely used magnesium die casting alloy (9% Al, 0.7% Zn, 0.2% Mn), offering the best combination of castability, room-temperature strength, and corrosion resistance among magnesium grades. At 1.81 g/cm³—33% lighter than aluminum...
AZ91D is the most widely used magnesium die casting alloy (9% Al, 0.7% Zn, 0.2% Mn), offering the best combination of castability, room-temperature strength, and corrosion resistance among magnesium grades. At 1.81 g/cm³—33% lighter than aluminum and 77% lighter than steel—it is the lightest structural metal commercially available. The high aluminum content provides good fluidity for thin-wall casting and adequate as-cast strength. Used for laptop cases, camera bodies, automotive steering wheels, and power tool housings where weight reduction is paramount. Not suitable for service above 120°C due to creep from Mg17Al12 phase coarsening—use AS or AE series alloys for elevated-temperature applications. Requires corrosion-protective coatings (conversion coating + powder coat or e-coat) for exterior service.
Quick Facts
| Category | Magnesium Alloy |
| Standard | ASTM B94 |
| Density | 1.81 g/cm³ |
| Yield Strength | 160 MPa (23 ksi) as-cast |
| Tensile Strength | 230 MPa (33 ksi) as-cast |
Global Equivalents & Cross-Reference
🧮 Material Weight Calculator
Calculate the weight based on this material's density: 1.81 g/cm³
Frequently Asked Questions
What are the main limitations of AZ91D magnesium?
(1) Poor elevated-temperature creep resistance above 120°C—Mg17Al12 phase coarsens, (2) galvanic corrosion risk when in contact with dissimilar metals (steel fasteners must be coated/isolated), (3) limited ductility (3% elongation) and notch sensitivity, (4) flammable machining chips require Class D fire extinguishers and careful chip management, (5) more expensive per kg than aluminum or steel—cost-effective only when the weight savings justify the higher material cost.
References & International Standards
- ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
- International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
- American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
- European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu