Aluminum A356
AA A356 · UNS A13560 · EN AlSi7Mg0.3 · GB ZL101A
A356 is a high-purity Al–7Si–0.3Mg foundry alloy (low Fe version of 356) used for sand, permanent-mould and low-pressure castings that must be heat treated to useful strength.
A356 tempers and conditions
A356 is supplied in 6 conditions, soft to hard.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated and naturally aged | Choose when maximum ductility and impact toughness matter more than yield strength, or when the part will be straightened/formed after solution treatment. | 110 | 195 | 12 | 60 HB | 38 % IACS |
T5, stress relieved by stretching | Low-cost, low-distortion temper for parts needing dimensional stability and moderate strength without the quench of a full T6. | 138 | 172 | 2 | 60 HB | 41 % IACS |
Solution treated and fully over-aged | Pick for maximum thermal/dimensional stability and lowest residual stress, e.g. optical or machined precision castings, accepting reduced strength. | 145 | 190 | 4 | 65 HB | 42 % IACS |
Solution heat treated and artificially aged | The default structural condition: peak strength with usable ductility for wheels, suspension parts, pump and housing castings. | 165 | 230 | 4 | 75 HB | 39 % IACS |
Solution heat treated and overaged (stabilized) | Use where dimensional stability at elevated temperature and lower residual stress are more important than peak strength (engine and instrument castings). | 185 | 225 | 3 | 75 HB | 41 % IACS |
T6 variant, underaged | Specify for permanent-mould, low-pressure or HIP-quality castings where the fine dendrite arm spacing allows T6 strength with much higher elongation. | 207 | 283 | 8 | 90 HB | 39 % IACS |
What is A356?
A356 is a high-purity Al–7Si–0.3Mg foundry alloy (low Fe version of 356) used for sand, permanent-mould and low-pressure castings that must be heat treated to useful strength. It combines excellent castability and pressure tightness with good corrosion resistance and, after T6, a strength/ductility balance suitable for wheels, structural brackets and housings. Limits are the modest absolute strength versus wrought 6000/7000 series, sensitivity of ductility to porosity and Si-eutectic morphology (Sr/Na modification and grain refining are essential), and mediocre decorative anodizing because of the high silicon content. A356 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 557°C (1,035 °F). A356 has a yield strength of 165 MPa (23.9 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 58% of aluminum grades. Elongation at break is 4% and the elastic modulus is 72.4 GPa (10.5 Msi).
What is A356 used for?
- Aerospace castings
- Wheels
- Valve bodies
Advantages
- Good corrosion resistance — 68/100, better than 75% of aluminum grades
A356 properties
Typical room-temperature values; bars are the position among aluminum grades.
Physical3
A356 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 557°C (1,035 °F).
Mechanical14
A356 has a yield strength of 165 MPa (23.9 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 58% of aluminum grades. Elongation at break is 4% and the elastic modulus is 72.4 GPa (10.5 Msi).
Thermal6
A356 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 21.4 µm/m·K (11.9 µin/in·°F).
Electrical3
A356 conducts electricity at 39 % IACS, better than 65% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 75% of aluminum grades.
Sustainability4
Producing a kilogram of A356 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 50%.
Manufacturability8
A356's machinability is good (68/100, better than 67% of aluminum grades); weldability very good (80/100); formability poor (15/100).
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. A356 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A356
Is A356 easy to machine?
Machines cleanly with sharp positive-rake carbide or PCD at high speed; the Si eutectic is abrasive so HSS tools wear fast — flood coolant, avoid built-up edge, T6 gives better finish than as-cast.
Can A356 be welded?
Readily TIG/MIG welded with 4043 (or 4145) filler; re-solution + age after welding to restore properties, and expect porosity if the casting was impregnated or not degassed.
Can A356 be formed, bent or molded?
Foundry alloy with outstanding fluidity for sand, permanent-mould and low-pressure casting — Sr modification, Ti-B grain refining, degassing and controlled solidification set the final ductility; not suitable for cold forming.
Manufacturability
The process limits FabDigit applies to A356. Every A356 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better68 / 100 |
|---|---|
| ISO material group | N.3 |
| Cutting speed (rough / finish) | 220 / 260 m/min |
| Minimum wall | 1 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / 0.8 µm |
| Hardenable after machining | No |
A356 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 former; Sr or Na modification usual | 6.5 – 7.5 | 7 |
| MgMg2Si precipitation strengthening | 0.25 – 0.45 | 0.35 |
| Felow-Fe requirement distinguishes A356 from 356 | ≤ 0.2 | 0.12 |
| Cu | ≤ 0.2 | 0.05 |
| Mn | ≤ 0.1 | 0.03 |
| Zn | ≤ 0.1 | 0.03 |
| Tigrain refinement (usually with B) | ≤ 0.2 | 0.12 |
| Others (each)total others 0.15 max | ≤ 0.05 | |
| Al | balance |
What surface finishes work on A356?
Hard anodize for wear and chromate/e-coat/powder for appearance; clear decorative anodizing looks grey and mottled from the silicon, and porous surfaces should be resin-impregnated before plating or painting.
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 A356 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does A356 cost?
A356 is a standard-cost aluminum ($$), cheaper than about 81% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
A356 — frequently asked
What is A356 used for?
A356 is typically used for aerospace castings, wheels and valve bodies. In short: heat-treatable Al-Si-Mg cast.
What is the yield strength of A356?
A356 has a typical yield strength of 165 MPa (23.9 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 58% of aluminum grades. Strength varies by condition: see the 6 listed tempers.
Is A356 easy to machine?
Reasonably — machinability is rated good (68/100, better than 67% of aluminum grades). Machines cleanly with sharp positive-rake carbide or PCD at high speed; the Si eutectic is abrasive so HSS tools wear fast — flood coolant, avoid built-up edge, T6 gives better finish than as-cast.
Can A356 be welded?
Yes — weldability is rated very good (80/100). Readily TIG/MIG welded with 4043 (or 4145) filler; re-solution + age after welding to restore properties, and expect porosity if the casting was impregnated or not degassed.
What surface finishes work on A356?
Hard anodize for wear and chromate/e-coat/powder for appearance; clear decorative anodizing looks grey and mottled from the silicon, and porous surfaces should be resin-impregnated before plating or painting.
Can A356 be formed, bent or molded?
Foundry alloy with outstanding fluidity for sand, permanent-mould and low-pressure casting — Sr modification, Ti-B grain refining, degassing and controlled solidification set the final ductility; not suitable for cold forming.
What is the maximum service temperature of A356?
A356 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does A356 cost?
A356 is a standard-cost aluminum ($$), cheaper than about 81% 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 A356?
Yes — A356 is available for CNC machining and casting & forging; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B26/B26M — Aluminum-Alloy Sand Castings — ASTM International (2018)
- ASTM B108/B108M — Aluminum-Alloy Permanent Mold Castings — ASTM International (2019)
- Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot (Pink Sheets) — The Aluminum Association (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- GB/T 1173 (ZL101A) (2013)
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.