Magnesium Alloy AM20 vs AZ91D
Magnesium Alloy · grade comparison
Magnesium Alloy AM20 and AZ91D are both magnesium alloy grades. AZ91D is the stronger of the two: yield strength 160 MPa (23.2 ksi) against 90 MPa (13.1 ksi) for AM20, about 78% more; tensile strength follows at 230 MPa (33.4 ksi) vs 195 MPa (28.3 ksi). In exchange, AM20 is the more ductile: elongation 12% versus 3% for AZ91D, and AZ91D is harder (63 HB vs 45 HB). AZ91D runs hotter in service (120°C vs 110°C continuous) and AM20 conducts heat better (100 W/m·K vs 72 W/m·K). On the shop floor, AM20 welds better (50 vs 40 out of 100).
AM20Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
AZ91DChoose it when strength drives the design, or when the part sees heat.
AM20 vs AZ91D: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all magnesium alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all magnesium alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 45 GPa6.5 Msi · Shear Modulus 17 GPa2.5 Msi · Bulk Modulus 45 GPa6.5 Msi · Poisson's Ratio 0.35
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Latent Heat of Fusion
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 1,020 J/kg·K0.24 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 26 µm/m·K14.4 µin/in·°F · Min Service Temperature -60°C-76 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -1.55 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Same in both: Brazeability / Solderability 20 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Typical Recycled Content
Same in both: Embodied Water 500 L/kg59.9 gal/lb
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
Strength versus weight
Yield strength against density for every magnesium alloy grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | AM20 | AZ91D |
|---|---|---|
| CNC machining | — | Yes |
| Casting & forging | — | Yes |
| Default condition | — | As Cast |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | — | 0.8 mm |
| Best machined surface | — | Ra 0.8 µm |
| Anodizing Type II | — | Yes |
| Chem Film (Alodine) | — | Yes |
| E-Coating | — | Yes |
| Hard Anodize Type III w/ PTFE | — | Yes |
| Hard Anodizing Type III | — | Yes |
| Painting | — | Yes |
| Powder Coating | — | Yes |
AM20 vs AZ91D — frequently asked
Is AZ91D stronger than AM20?
Yes. AZ91D has a typical yield strength of 160 MPa (23.2 ksi) against 90 MPa (13.1 ksi) for AM20 — about 78% more. Tensile strength is 230 MPa (33.4 ksi) vs 195 MPa (28.3 ksi).
Which is cheaper, AM20 or AZ91D?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which welds better, AM20 or AZ91D?
AM20. Its weldability rates fair (50/100) against fair (40/100) for AZ91D.
Ready to make it?
Upload a CAD file and FabDigit prices the part in AM20 and AZ91D side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.