Magnesium Alloy AZ31B vs HK31A
Magnesium Alloy · grade comparison
Magnesium Alloy AZ31B and HK31A are both magnesium alloy grades. HK31A is the stronger of the two: yield strength 200 MPa (29 ksi) against 150 MPa (21.8 ksi) for AZ31B, about 33% more. In exchange, AZ31B is the more ductile: elongation 21% versus 9% for HK31A, and HK31A is harder (57 HB vs 49 HB). HK31A runs hotter in service (315°C vs 120°C continuous) and HK31A conducts heat better (111 W/m·K vs 96 W/m·K).
AZ31BChoose it when the part is bent, formed or impact-loaded.
HK31AChoose it when strength drives the design, or when the part sees heat.
AZ31B vs HK31A: 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.
Bulk Modulus
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, Rockwell B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 45 GPa6.5 Msi · Shear Modulus 17 GPa2.5 Msi · Poisson's Ratio 0.35 · Tensile Strength (Ultimate) 255 MPa37 ksi
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
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Latent Heat of Fusion 340 J/g146 BTU/lb
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.
Formability (cold)
Castability
Polishability
Same in both: Machinability 95 / 100 · Machinability Rating (AISI 1212 = 100 %) 400% · Weldability 70 / 100 · Brazeability / Solderability 25 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Typical Recycled Content
Same in both: Embodied Carbon (primary production) 32 kg CO₂/kg · 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 | AZ31B | HK31A |
|---|---|---|
| Default condition | O | H24 |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | 0.8 mm | 0.8 mm |
| Best machined surface | Ra 0.8 µm | Ra 0.8 µm |
Both are offered for CNC machining and Sheet metal. Both take the same 7 finishes: Anodizing Type II, Chem Film (Alodine), E-Coating, Hard Anodize Type III w/ PTFE, Hard Anodizing Type III, Painting, Powder Coating.
AZ31B vs HK31A — frequently asked
Is HK31A stronger than AZ31B?
Yes. HK31A has a typical yield strength of 200 MPa (29 ksi) against 150 MPa (21.8 ksi) for AZ31B — about 33% more. Tensile strength is 255 MPa (37 ksi) vs 255 MPa (37 ksi).
Which is cheaper, AZ31B or HK31A?
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.
When should I choose AZ31B over HK31A?
Pick AZ31B when the part is bent, formed or impact-loaded. Pick HK31A when strength drives the design, or when the part sees heat.
Ready to make it?
Upload a CAD file and FabDigit prices the part in AZ31B and HK31A 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.