Magnesium Alloy HK31A-F vs HK31A-O
Magnesium Alloy · HK31A temper comparison
HK31A-F and HK31A-O are two conditions of the same magnesium alloy grade, HK31A: F (as fabricated) versus O (annealed). The chemistry is identical, so every difference below comes from the condition. HK31A-O is the stronger of the two: yield strength 140 MPa (20.3 ksi) against 95 MPa (13.8 ksi) for HK31A-F, about 47% more; tensile strength follows at 230 MPa (33.4 ksi) vs 185 MPa (26.8 ksi). HK31A-O is the more ductile: elongation 23% versus 5% for HK31A-F, and HK31A-F is harder (50 HB vs 45 HB).
HK31A-OChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
HK31A-F vs HK31A-O: 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)
Hardness, Brinell
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 1.79 g/cm³0.06 lb/in³ · Melting Point (Solidus) 588°C1,090 °F · Liquidus Temperature 650°C1,202 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 1,005 J/kg·K0.24 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 26.1 µm/m·K14.5 µin/in·°F · Latent Heat of Fusion 340 J/g146 BTU/lb · Min Service Temperature -100°C-148 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -1.55 V · Corrosion Resistance 20 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Same in both: Machinability Rating (AISI 1212 = 100 %) 400% · Castability 75 / 100 · Brazeability / Solderability 25 / 100 · Polishability 50 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 350 MJ/kg150,473 BTU/lb · Embodied Carbon (primary production) 32 kg CO₂/kg · Embodied Water 500 L/kg59.9 gal/lb · Typical Recycled Content 5%
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.
HK31A-F vs HK31A-O — frequently asked
Is HK31A-O stronger than HK31A-F?
Yes. HK31A-O has a typical yield strength of 140 MPa (20.3 ksi) against 95 MPa (13.8 ksi) for HK31A-F — about 47% more. Tensile strength is 230 MPa (33.4 ksi) vs 185 MPa (26.8 ksi).
Which condition does FabDigit quote by default, F or O?
H24 is the default HK31A condition in the FabDigit quote flow (neither F nor O). 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.
When should I choose HK31A-F over HK31A-O?
Pick HK31A-O when strength drives the design, or when the part is bent, formed or impact-loaded.
Ready to make it?
Upload a CAD file and FabDigit prices the part in HK31A-F and HK31A-O 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.