Aluminum 331.0 vs 355
Aluminum · grade comparison
Aluminum 331.0 and 355 are both aluminum grades. 331.0 is the stronger of the two: yield strength 195 MPa (28.3 ksi) against 180 MPa (26.1 ksi) for 355, about 8% more. In exchange, 355 is the more ductile: elongation 3% versus 1% for 331.0, and 331.0 is harder (95 HB vs 85 HB). 331.0 is stiffer (79 GPa vs 71 GPa) and 331.0 runs hotter in service (200°C vs 175°C continuous). On the shop floor, 355 machines more easily (good vs fair), 355 welds better (good vs fair), and 355 sits in a lower cost tier (budget, $) than 331.0 (standard, $$).
331.0Choose it when strength drives the design, or when the part sees heat.
355Choose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
331.0 vs 355: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all aluminum 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 aluminum 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.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Yield Strength (0.2% offset)
Elongation at Break
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Fracture Toughness (K_IC)
Same in both: Poisson's Ratio 0.33 · Tensile Strength (Ultimate) 250 MPa36.3 ksi · Shear Strength 195 MPa28.3 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
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 963 J/kg·K0.23 BTU/lb·°F · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Castability
Brazeability / Solderability
Polishability
Same in both: Formability (cold) 5 / 100
Sustainability
Primary-production footprint per kilogram.
Typical Recycled Content
Same in both: Embodied Energy (primary production) 200 MJ/kg85,985 BTU/lb · Embodied Carbon (primary production) 12 kg CO₂/kg · Embodied Water 1,100 L/kg132 gal/lb
Common Calculations
Ratios derived from the values above.
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
Same in both: Specific Strength (UTS / density) 92 kN·m/kg
Strength versus weight
Yield strength against density for every aluminum grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | 331.0 | 355 |
|---|---|---|
| CNC machining | — | Yes |
| Default condition | — | — |
| Relative cost | $$ Standard | $ Budget |
| Min. machined wall | — | 0.5 mm |
| Best machined surface | — | Ra 0.8 µm |
| Anodizing Type II | — | Yes |
| Cerakote | — | Yes |
| Chem Film (Alodine) | — | Yes |
| DLC | — | Yes |
| E-Coating | — | Yes |
| Electropolishing | — | Yes |
| Hard Anodize Type III w/ PTFE | — | Yes |
| Hard Anodizing Type III | — | Yes |
| Nickel Plating | — | Yes |
| PTFE Coating | — | Yes |
| Painting | — | Yes |
| Powder Coating | — | Yes |
They share 4 finishes: Electroless Nickel (EN), Epoxy Coating, Gold Plating, Silver Plating.
331.0 vs 355 — frequently asked
Is 331.0 stronger than 355?
Yes. 331.0 has a typical yield strength of 195 MPa (28.3 ksi) against 180 MPa (26.1 ksi) for 355 — about 8% more. Tensile strength is 250 MPa (36.3 ksi) vs 250 MPa (36.3 ksi).
Which is cheaper, 331.0 or 355?
355 is the lower-cost material: it sits in the budget tier ($) while 331.0 is standard ($$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, 331.0 or 355?
355. Its machinability rates good (62/100) against fair (40/100) for 331.0; for welding the order is 355 first (good, 55/100) then 331.0 (fair, 35/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 331.0 and 355 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.