Aluminum 204.0
AA 204.0 · UNS A02040
204.0 is an Al-Cu sand and permanent-mold casting alloy (A02040) supplied F, T4, T6 or T7, developing about 195 MPa yield and 320 MPa tensile with 8% elongation and HB 95.
Reference datasheet — 204.0 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the T4 condition
204.0 tempers and conditions
204.0 is supplied in 4 conditions, soft to hard. T4 is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Rarely supplied; as-cast 204.0 has low strength and is normally only an intermediate state before solution treatment. | 110 | 170 | 4 | 60 HB | 38 % IACS |
T4Default Solution heat treated and naturally aged | The standard commercial condition for 204.0 — best combination of high strength with useful ductility and toughness. | 195 | 320 | 8 | 95 HB | 33 % IACS |
Solution heat treated and overaged (stabilized) | Overaged condition used when dimensional stability at elevated temperature and reduced residual stress are more important than peak strength. | 250 | 300 | 5 | 105 HB | 40 % IACS |
Solution heat treated and artificially aged | Pick when peak strength and hardness matter more than ductility and toughness; elongation drops sharply versus T4. | 285 | 350 | 3 | 120 HB | 37 % IACS |
What is 204.0?
204.0 is an Al-Cu sand and permanent-mold casting alloy (A02040) supplied F, T4, T6 or T7, developing about 195 MPa yield and 320 MPa tensile with 8% elongation and HB 95. Engineers choose it for high-strength machined castings such as aircraft wheels and structural brackets, helped by a machinability rating of 85 and 121 W/m·K thermal conductivity. It is not suited to pressure-tight parts: the wide freezing range brings shrinkage and hot-tear sensitivity, fusion weldability is poor, and corrosion protection needs paint or conversion coating. Al-Si alloys such as 356.0 are the alternative where castability and leak tightness matter. 204.0 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 571°C (1,060 °F). 204.0 has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 320 MPa (46.4 ksi) — stronger than 51% of aluminum grades. Elongation at break is 8% and the elastic modulus is 72 GPa (10.4 Msi).
What is 204.0 used for?
- aircraft wheels
- structural castings
- brackets
Advantages
- Easy to machine — 85/100, better than 95% of aluminum grades
Limitations
- Needs corrosion protection — 35/100, worse than 85% of aluminum grades
- Limited formability — 10/100, worse than 80% of aluminum grades
- Poor heat conductor — 121 W/m·K (69.9 BTU/hr·ft·°F), worse than 76% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
204.0 properties
Typical room-temperature values for 204.0-T4; bars are the position among aluminum grades.
Physical3
204.0 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 571°C (1,060 °F).
Mechanical12
204.0 has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 320 MPa (46.4 ksi) — stronger than 51% of aluminum grades. Elongation at break is 8% and the elastic modulus is 72 GPa (10.4 Msi).
Thermal6
204.0 is rated for continuous service to 150°C (302 °F). It conducts heat at 121 W/m·K (69.9 BTU/hr·ft·°F), worse than 76% of aluminum grades. Thermal expansion is 22.7 µm/m·K (12.6 µin/in·°F).
Electrical3
204.0 conducts electricity at 33 % IACS, worse than 57% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (35/100), worse than 85% of aluminum grades.
Sustainability4
Producing a kilogram of 204.0 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 15%.
Manufacturability8
204.0's machinability is excellent (85/100, better than 95% of aluminum grades); weldability poor (25/100); 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. 204.0 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 204.0
Is 204.0 easy to machine?
Machines very well in T4/T6 with sharp carbide tools, high speed and moderate feed; chips break cleanly, use flood coolant to avoid built-up edge.
Can 204.0 be welded?
Poor fusion weldability — wide freezing range causes hot cracking; repair welds (4043/2319) require preheat, low restraint and post-weld re-solution treatment to restore properties.
Can 204.0 be formed, bent or molded?
Sand and permanent-mold casting only; needs generous risering, chills and controlled directional solidification because of high shrinkage and hot-tear sensitivity — do not specify for pressure-tight parts.
204.0 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 |
|---|---|---|
| Siimpurity limit | ≤ 0.2 | |
| Fe0.15 max for premium/high-toughness practice | ≤ 0.35 | |
| Cumain strengthening element | 4.2 – 5 | 4.6 |
| Mn | ≤ 0.1 | |
| Mg | 0.15 – 0.35 | 0.25 |
| Ni | ≤ 0.05 | |
| Zn | ≤ 0.1 | |
| Sn | ≤ 0.05 | |
| Tigrain refiner | 0.15 – 0.3 | 0.22 |
| Others (each) | ≤ 0.05 | |
| Others (total) | ≤ 0.15 | |
| Al | balance |
What surface finishes work on 204.0?
Take painting or chromate/anodize+seal for corrosion protection; sulfuric anodize gives a dark uneven film due to Cu, so use paint or conversion coat for cosmetic parts.
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).
Organic Coating
Equivalent designations
Standards and trade names that resolve to Aluminum 204.0 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- A02040
How much does 204.0 cost?
204.0 is a premium-cost aluminum ($$$), cheaper than about 51% 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.
204.0 — frequently asked
What is 204.0 used for?
204.0 is typically used for aircraft wheels, structural castings and brackets. In short: high-strength Al-Cu casting; excellent machinability, rating 85; not for pressure-tight parts.
What is the yield strength of 204.0?
204.0 has a typical yield strength of 195 MPa (28.3 ksi) and a tensile strength of 320 MPa (46.4 ksi) — stronger than 51% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 204.0 easy to machine?
Yes — machinability is rated excellent (85/100, better than 95% of aluminum grades). Machines very well in T4/T6 with sharp carbide tools, high speed and moderate feed; chips break cleanly, use flood coolant to avoid built-up edge.
Can 204.0 be welded?
Not readily — weldability is rated poor (25/100). Poor fusion weldability — wide freezing range causes hot cracking; repair welds (4043/2319) require preheat, low restraint and post-weld re-solution treatment to restore properties.
What surface finishes work on 204.0?
Take painting or chromate/anodize+seal for corrosion protection; sulfuric anodize gives a dark uneven film due to Cu, so use paint or conversion coat for cosmetic parts.
Can 204.0 be formed, bent or molded?
Sand and permanent-mold casting only; needs generous risering, chills and controlled directional solidification because of high shrinkage and hot-tear sensitivity — do not specify for pressure-tight parts.
What is the maximum service temperature of 204.0?
204.0 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.
What is the difference between 204.0-T4 and 204.0-T6?
T4 is the default condition — the standard commercial condition for 204.0 — best combination of high strength with useful ductility and toughness. T6: pick when peak strength and hardness matter more than ductility and toughness; elongation drops sharply versus T4. Yield strength is 195 MPa in T4 versus 285 MPa in T6.
How much does 204.0 cost?
204.0 is a premium-cost aluminum ($$$), cheaper than about 51% 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.
Sources
- Registration Record of Aluminum Association Alloy 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)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- EN 1706 — Aluminium and aluminium alloys: castings (AlCu4MgTi / AlCu4Ti) — CEN (2020)
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.