Magnesium Alloy AZ91D-T4 vs AZ91D-T6
Magnesium Alloy · AZ91D temper comparison
AZ91D-T4 and AZ91D-T6 are two conditions of the same magnesium alloy grade, AZ91D: T4 (solution heat treated and naturally aged) versus T6 (solution heat treated and artificially aged). The chemistry is identical, so every difference below comes from the condition. AZ91D-T6 is the stronger of the two: yield strength 145 MPa (21 ksi) against 90 MPa (13.1 ksi) for AZ91D-T4, about 61% more. In exchange, AZ91D-T4 is the more ductile: elongation 14% versus 6% for AZ91D-T6, and AZ91D-T6 is harder (70 HB vs 55 HB). On the shop floor, AZ91D-T4 welds better (good vs fair).
AZ91D-T4Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
AZ91D-T6Choose it when strength drives the design.
AZ91D-T4 vs AZ91D-T6: 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.
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 · Tensile Strength (Ultimate) 275 MPa39.9 ksi
Physical
Density and transition temperatures.
Same in both: Density 1.81 g/cm³0.07 lb/in³ · Melting Point (Solidus) 470°C878 °F · Liquidus Temperature 595°C1,103 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 72 W/m·K41.6 BTU/hr·ft·°F · 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 · Latent Heat of Fusion 373 J/g160 BTU/lb · Min Service Temperature -60°C-76 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Same in both: Electrical Resistivity 1.41×10⁻⁷ Ω·m5.55 µΩ·in
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
Weldability
Formability (cold)
Polishability
Same in both: Machinability Rating (AISI 1212 = 100 %) 300% · Castability 95 / 100 · Brazeability / Solderability 20 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 320 MJ/kg137,575 BTU/lb · Embodied Carbon (primary production) 32 kg CO₂/kg · Embodied Water 500 L/kg59.9 gal/lb · Typical Recycled Content 35%
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.
AZ91D-T4 vs AZ91D-T6 — frequently asked
Is AZ91D-T6 stronger than AZ91D-T4?
Yes. AZ91D-T6 has a typical yield strength of 145 MPa (21 ksi) against 90 MPa (13.1 ksi) for AZ91D-T4 — about 61% more. Tensile strength is 275 MPa (39.9 ksi) vs 275 MPa (39.9 ksi).
Which condition does FabDigit quote by default, T4 or T6?
As Cast is the default AZ91D condition in the FabDigit quote flow (neither T4 nor T6). The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which welds better, AZ91D-T4 or AZ91D-T6?
AZ91D-T4. Its weldability rates good (60/100) against fair (50/100) for AZ91D-T6.
Ready to make it?
Upload a CAD file and FabDigit prices the part in AZ91D-T4 and AZ91D-T6 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.