Aluminum 355 vs 390
Aluminum · grade comparison
Aluminum 355 and 390 are both aluminum grades, both cast al. 390 is the stronger of the two: yield strength 241 MPa (35 ksi) against 180 MPa (26.1 ksi) for 355, about 34% more; tensile strength follows at 279 MPa (40.5 ksi) vs 250 MPa (36.3 ksi). In exchange, 355 is the more ductile: elongation 3% versus 1% for 390, and 390 is harder (120 HB vs 85 HB). 390 is stiffer (81 GPa vs 71 GPa) and 355 conducts heat better (151 W/m·K vs 134 W/m·K). On the shop floor, 355 machines more easily (good vs poor), 355 welds better (good vs poor), and 355 sits in a lower cost tier (budget, $) than 390 (standard, $$).
355Choose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
390Choose it when strength drives the design.
355 vs 390: 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)
Yield Strength (0.2% offset)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Hardness, Brinell
Charpy V-Notch Impact (RT)
Same in both: Poisson's Ratio 0.33
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)
Latent Heat of Fusion
Min Service Temperature
Same in both: Max Service Temperature (continuous) 175°C347 °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
Polishability
Same in both: Machinability Rating (AISI 1212 = 100 %) 60%
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 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 | 390 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $ Budget | $$ Standard |
| Min. machined wall | 0.5 mm | 0.5 mm |
| Best machined surface | Ra 0.8 µm | Ra 0.8 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 390 — frequently asked
Is 390 stronger than 355?
Yes. 390 has a typical yield strength of 241 MPa (35 ksi) against 180 MPa (26.1 ksi) for 355 — about 34% more. Tensile strength is 279 MPa (40.5 ksi) vs 250 MPa (36.3 ksi).
Which is cheaper, 355 or 390?
355 is the lower-cost material: it sits in the budget tier ($) while 390 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 390?
355. Its machinability rates good (62/100) against poor (28/100) for 390; for welding the order is 355 first (good, 55/100) then 390 (poor, 22/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 355 and 390 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.