Aluminum 356
AA 356 · UNS A03560 · EN AlSi7Mg · BS LM25 · also SG70A
356 (AlSi7Mg) is the workhorse heat-treatable aluminium–silicon–magnesium casting alloy, used for sand, permanent-mould and low-pressure castings such as wheels, cylinder heads, pump and valve bodies and structural aerospace castings.
356 tempers and conditions
356 is supplied in 5 conditions, soft to hard.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
T5, stress relieved by stretching | Low-cost stabilising age (~225 °C) that raises yield and improves machinability/dimensional stability without solution-treat distortion. | 138 | 172 | 2 | 60 HB | 43 % IACS |
Solution heat treated and artificially aged | Standard structural condition: best combination of strength and ductility for wheels, housings and aerospace castings. | 186 | 262 | 5 | 80 HB | 39 % IACS |
Solution treated and strongly over-aged | Softest heat-treated condition; chosen when residual-stress relief and long-term dimensional/thermal stability outweigh strength. | 186 | 196 | 3 | 60 HB | 41 % IACS |
T6 variant, underaged | Higher-strength ageing schedule used on A356 premium-quality permanent-mould and low-pressure castings. | 207 | 283 | 10 | 90 HB | 39 % IACS |
Solution heat treated and overaged (stabilized) | Over-aged for dimensional stability and higher yield at slight ductility cost; suits parts machined to tight tolerance or run warm. | 207 | 234 | 2 | 75 HB | 40 % IACS |
What is 356?
356 (AlSi7Mg) is the workhorse heat-treatable aluminium–silicon–magnesium casting alloy, used for sand, permanent-mould and low-pressure castings such as wheels, cylinder heads, pump and valve bodies and structural aerospace castings. It combines excellent castability and fluidity, good pressure tightness, good weldability and good corrosion resistance with useful T6 strength after solution treating and ageing. Limits are moderate absolute strength, sensitivity of ductility to iron content and dendrite/porosity quality (hence the low-Fe A356 variant), abrasive machining behaviour from the eutectic silicon, and a grey, non-decorative anodic film. 356 has a density of 2.67 g/cm³ (0.0965 lb/in³), lighter than 78% of aluminum grades. It melts at 557°C (1,035 °F). 356 has a yield strength of 186 MPa (27 ksi) and a tensile strength of 262 MPa (38 ksi) — weaker than 52% of aluminum grades. Elongation at break is 5% and the elastic modulus is 72.4 GPa (10.5 Msi).
What is 356 used for?
- Cast automotive wheels
- Cylinder heads and cylinder blocks
- Pump housings
- Valve bodies
- Structural aerospace castings
- Low-pressure cast intake manifolds
- Gearbox and transmission housings
Limitations
- Limited formability — 10/100, worse than 80% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
356 properties
Typical room-temperature values; bars are the position among aluminum grades.
Physical3
356 has a density of 2.67 g/cm³ (0.0965 lb/in³), lighter than 78% of aluminum grades. It melts at 557°C (1,035 °F).
Mechanical13
356 has a yield strength of 186 MPa (27 ksi) and a tensile strength of 262 MPa (38 ksi) — weaker than 52% of aluminum grades. Elongation at break is 5% and the elastic modulus is 72.4 GPa (10.5 Msi).
Thermal6
356 is rated for continuous service to 150°C (302 °F). It conducts heat at 151 W/m·K (87.2 BTU/hr·ft·°F), better than 63% of aluminum grades. Thermal expansion is 21.5 µm/m·K (11.9 µin/in·°F).
Electrical3
356 conducts electricity at 39 % IACS, better than 65% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), better than 67% of aluminum grades.
Sustainability4
Producing a kilogram of 356 takes about 200 MJ of energy and emits 12.5 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 60%.
Manufacturability8
356's machinability is very good (70/100, better than 72% of aluminum grades); weldability very good (78/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the aluminum family
Yield strength against density for every aluminum grade FabDigit runs. 356 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 356
Is 356 easy to machine?
Machines freely with sharp PCD or polished-flute carbide tooling and flood coolant; eutectic silicon is abrasive, so PCD is preferred for volume, and T6/T7 cuts cleaner than as-cast F.
Can 356 be welded?
Readily TIG/MIG welded with 4043 or 4145 filler; re-solution and re-age locally welded structural castings, and avoid welding into gas-porous or heavily impregnated regions.
Can 356 be formed, bent or molded?
Excellent fluidity and pressure tightness in sand, permanent-mould and low-pressure casting; Sr/Na modification plus Ti-B grain refining and directional solidification are key to ductility, and thin risers/hot spots cause shrinkage porosity.
Manufacturability
The process limits FabDigit applies to 356. Every 356 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better70 / 100 |
|---|---|
| ISO material group | N.1 |
| Cutting speed (rough / finish) | 350 / 420 m/min |
| Minimum wall | 0.5 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 8× diameter |
| Best surface (machined / polished) | Ra 0.8 / — |
| Hardenable after machining | No |
356 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Sieutectic-forming addition; Sr or Na modified in most foundry practice | 6.5 – 7.5 | 7 |
| MgA356 restricted to 0.25–0.45 % | 0.2 – 0.45 | 0.35 |
| FeA356 max 0.20 %, A356.2 ingot max 0.12 % — low Fe improves ductility | ≤ 0.6 | 0.25 |
| CuA356 max 0.20 % | ≤ 0.25 | 0.05 |
| MnA356 max 0.10 % | ≤ 0.35 | 0.05 |
| ZnA356 max 0.10 % | ≤ 0.35 | 0.05 |
| Tigrain refiner (Al-Ti-B) | ≤ 0.25 | 0.12 |
| Others (each)total 0.15 % max | ≤ 0.05 | |
| Al | balance |
What surface finishes work on 356?
Takes chemical conversion coating, primer and paint well; hard or sulfuric anodize gives a protective but dark grey, blotchy film, and mirror polishing is limited by silicon particles.
Surface treatments FabDigit runs on aluminum parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Conversion Coating
PVD Coating
Equivalent designations
Standards and trade names that resolve to Aluminum 356 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 356 cost?
356 is a budget-cost aluminum ($), cheaper than about 82% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
356 — frequently asked
What is 356 used for?
356 is typically used for cast automotive wheels, cylinder heads and cylinder blocks, pump housings, valve bodies, structural aerospace castings and low-pressure cast intake manifolds. In short: most common sand cast.
What is the yield strength of 356?
356 has a typical yield strength of 186 MPa (27 ksi) and a tensile strength of 262 MPa (38 ksi) — weaker than 52% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is 356 easy to machine?
Yes — machinability is rated very good (70/100, better than 72% of aluminum grades). Machines freely with sharp PCD or polished-flute carbide tooling and flood coolant; eutectic silicon is abrasive, so PCD is preferred for volume, and T6/T7 cuts cleaner than as-cast F.
Can 356 be welded?
Yes — weldability is rated very good (78/100). Readily TIG/MIG welded with 4043 or 4145 filler; re-solution and re-age locally welded structural castings, and avoid welding into gas-porous or heavily impregnated regions.
What surface finishes work on 356?
Takes chemical conversion coating, primer and paint well; hard or sulfuric anodize gives a protective but dark grey, blotchy film, and mirror polishing is limited by silicon particles.
Can 356 be formed, bent or molded?
Excellent fluidity and pressure tightness in sand, permanent-mould and low-pressure casting; Sr/Na modification plus Ti-B grain refining and directional solidification are key to ductility, and thin risers/hot spots cause shrinkage porosity.
What is the maximum service temperature of 356?
356 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 356 cost?
356 is a budget-cost aluminum ($), cheaper than about 82% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 356?
Yes — 356 is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- Aluminum Association Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot (Pink Sheets) — The Aluminum Association (2018)
- ASTM B26/B26M — Aluminum-Alloy Sand Castings — ASTM International (2018)
- ASTM B108/B108M — Aluminum-Alloy Permanent Mold Castings — ASTM International (2019)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- GB/T 1173 (ZL101/ZL101A) — SAC (2013)
- EN 1706 AC-42000 / AC-42100 AlSi7Mg — CEN (2020)
- Aluminum Casting Technology / AFS foundry data — American Foundry Society (1997)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.