Magnesium Alloy AZ91D Stress Relieved vs AZ91D-T4
Magnesium Alloy · AZ91D temper comparison
AZ91D Stress Relieved and AZ91D-T4 are two conditions of the same magnesium alloy grade, AZ91D: Stress Relieved versus T4 (solution heat treated and naturally aged). The chemistry is identical, so every difference below comes from the condition. AZ91D Stress Relieved is the stronger of the two: yield strength 150 MPa (21.8 ksi) against 90 MPa (13.1 ksi) for AZ91D-T4, about 67% more. In exchange, AZ91D-T4 is the more ductile: elongation 14% versus 3.5% for AZ91D Stress Relieved, and AZ91D Stress Relieved is harder (60 HB vs 55 HB). On the shop floor, AZ91D-T4 welds better (good vs fair).
AZ91D Stress RelievedChoose it when strength drives the design.
AZ91D-T4Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
AZ91D Stress Relieved vs AZ91D-T4: 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.
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.
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 · Max Service Temperature (continuous) 120°C248 °F · 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
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Polishability
Same in both: 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 Stress Relieved vs AZ91D-T4 — frequently asked
Is AZ91D Stress Relieved stronger than AZ91D-T4?
Yes. AZ91D Stress Relieved has a typical yield strength of 150 MPa (21.8 ksi) against 90 MPa (13.1 ksi) for AZ91D-T4 — about 67% more. Tensile strength is 220 MPa (31.9 ksi) vs 275 MPa (39.9 ksi).
Which condition does FabDigit quote by default, Stress Relieved or T4?
As Cast is the default AZ91D condition in the FabDigit quote flow (neither Stress Relieved nor T4). 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 Stress Relieved or AZ91D-T4?
AZ91D-T4. Its weldability rates good (60/100) against fair (42/100) for AZ91D Stress Relieved.
Ready to make it?
Upload a CAD file and FabDigit prices the part in AZ91D Stress Relieved and AZ91D-T4 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.