Aluminum 204.0-T7
Temper
AA 204.0 · UNS A02040
T7 = 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.
Values for the T7 condition
Other 204.0 tempers and conditions
204.0 is listed in 4 conditions; see the grade overview at 204.0.
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 |
T7This page 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-T7?
204.0-T7 is 204.0 in the T7 temper — overaged condition used when dimensional stability at elevated temperature and reduced residual stress are more important than peak strength. 204.0-T7 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 300 MPa (43.5 ksi) — stronger than 65% of aluminum grades. Elongation at break is 5% and the elastic modulus is 72 GPa (10.4 Msi). 204.0-T7 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). T4 is the default condition FabDigit quotes; T7 is available on request or by drawing note.
Advantages
- Easy to machine — 86/100, better than 95% of aluminum grades
- High service temperature — 200°C (392 °F), better than 90% of aluminum grades
Limitations
- Limited formability — 5/100, worse than 94% of aluminum grades
- Needs corrosion protection — 38/100, worse than 79% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
204.0-T7 properties
Typical room-temperature values for 204.0-T7; 21 are specific to this condition. Other listed values are 204.0 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
204.0-T7 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-T7 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 300 MPa (43.5 ksi) — stronger than 65% of aluminum grades. Elongation at break is 5% and the elastic modulus is 72 GPa (10.4 Msi).
Thermal6
204.0-T7 is rated for continuous service to 200°C (392 °F). It conducts heat at 140 W/m·K (80.9 BTU/hr·ft·°F), worse than 52% of aluminum grades. Thermal expansion is 22.7 µm/m·K (12.6 µin/in·°F).
Electrical3
204.0-T7 conducts electricity at 40 % IACS, better than 72% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 79% of aluminum grades.
Sustainability4
Producing a kilogram of 204.0-T7 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-T7's machinability is excellent (86/100, better than 95% of aluminum grades); weldability poor (25/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 204.0-T7
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.
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.
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 | — |
204.0-T7 — frequently asked
What is 204.0-T7 used for?
204.0-T7 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-T7?
204.0-T7 has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 300 MPa (43.5 ksi) — stronger than 65% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 204.0-T7 easy to machine?
Yes — machinability is rated excellent (86/100, 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-T7 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-T7?
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-T7 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-T7?
204.0-T7 is rated for continuous use to about 200°C (392 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.