Aluminum 355 vs AL4
Aluminum · grade comparison
Aluminum 355 and AL4 are both aluminum grades. Both yield at about 180 MPa — strength does not separate them. AL4 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, AL4 welds better (very good vs good) and 355 sits in a lower cost tier (budget, $) than AL4 (standard, $$).
355Choose it when the part sees heat, or when cost is the deciding factor.
AL4Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
355 vs AL4: 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
Tensile Strength (Ultimate)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Compressive Strength
Charpy V-Notch Impact (RT)
Same in both: Poisson's Ratio 0.33 · Yield Strength (0.2% offset) 180 MPa26.1 ksi · 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
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Same in both: Machinability Rating (AISI 1212 = 100 %) 60% · Polishability 45 / 100
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 | AL4 |
|---|---|---|
| CNC machining | Yes | — |
| Default condition | — | — |
| Relative cost | $ Budget | $$ Standard |
| 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.
355 vs AL4 — frequently asked
What is the difference between 355 and AL4?
Aluminum 355 and AL4 are both aluminum grades. Both yield at about 180 MPa — strength does not separate them. AL4 is the more ductile: elongation 4% versus 3% for 355, and 355 is harder (85 HB vs 75 HB).
Which is cheaper, 355 or AL4?
355 is the lower-cost material: it sits in the budget tier ($) while AL4 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 welds better, 355 or AL4?
AL4. Its weldability rates very good (80/100) against good (55/100) for 355.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 355 and AL4 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.