Aluminum 355 vs A356
Aluminum · grade comparison
Aluminum 355 and A356 are both aluminum grades, both cast al. 355 is the stronger of the two: yield strength 180 MPa (26.1 ksi) against 165 MPa (23.9 ksi) for A356, about 9% more; tensile strength follows at 250 MPa (36.3 ksi) vs 230 MPa (33.4 ksi). In exchange, A356 is the more ductile: elongation 4% versus 3% for 355, and 355 is harder (85 HB vs 75 HB). 355 runs hotter in service (175°C vs 150°C continuous). On the shop floor, A356 welds better (very good vs good) and 355 sits in a lower cost tier (budget, $) than A356 (standard, $$).
355Choose it when strength drives the design, or when the part sees heat.
A356Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
355 vs A356: 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
Bulk Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Compressive Strength
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Shear Modulus 26.5 GPa3.8 Msi · Poisson's Ratio 0.33 · Fracture Toughness (K_IC) 20 MPa·√m18.2 ksi·√in
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
Thermal
How each material carries heat and how hot it can run.
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 151 W/m·K87.2 BTU/hr·ft·°F · Specific Heat Capacity 963 J/kg·K0.23 BTU/lb·°F · Latent Heat of Fusion 389 J/g167 BTU/lb · 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
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Water
Typical Recycled Content
Same in both: Embodied Energy (primary production) 200 MJ/kg85,985 BTU/lb · Embodied Carbon (primary production) 12 kg CO₂/kg
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 aluminum grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | 355 | A356 |
|---|---|---|
| Casting & forging | — | Yes |
| Default condition | — | — |
| Relative cost | $ Budget | $$ Standard |
| Min. machined wall | 0.5 mm | 1 mm |
| Best machined surface | Ra 0.8 µm | Ra 1.6 µm |
Both are offered for CNC machining. Both take the same 16 finishes: Anodizing Type II, Cerakote, Chem Film (Alodine), DLC, E-Coating, Electroless Nickel (EN), Electropolishing, Epoxy Coating, Gold Plating, Hard Anodize Type III w/ PTFE, Hard Anodizing Type III, Nickel Plating and 4 more.
355 vs A356 — frequently asked
Is 355 stronger than A356?
Yes. 355 has a typical yield strength of 180 MPa (26.1 ksi) against 165 MPa (23.9 ksi) for A356 — about 9% more. Tensile strength is 250 MPa (36.3 ksi) vs 230 MPa (33.4 ksi).
Which is cheaper, 355 or A356?
355 is the lower-cost material: it sits in the budget tier ($) while A356 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, 355 or A356?
A356, by a small margin. Both rate good for machinability — 68/100 against 62/100 for 355; for welding the order is A356 first (very good, 80/100) then 355 (good, 55/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 355 and A356 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.