Aluminum EN AC-21000-T4
Temper · default condition
EN AC-21000
T4 = solution heat treated and naturally aged
The standard EN 1706 delivery condition: best combination of strength, ductility and toughness for structural aerospace and motorsport castings.
Values for the T4 condition
Other EN AC-21000 tempers and conditions
EN AC-21000 is listed in 5 conditions; see the grade overview at EN AC-21000.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Rarely used commercially; only for non-structural parts or as the delivery state before customer heat treatment. | 95 | 170 | 2 | 62 HB | 35 % IACS |
T4DefaultThis page Solution heat treated and naturally aged | The standard EN 1706 delivery condition: best combination of strength, ductility and toughness for structural aerospace and motorsport castings. | 210 | 320 | 7 | 92 HB | 30 % IACS |
Solution treated and under-aged for high toughness | Under-aged compromise used on 201/206-type castings when both high strength and damage tolerance (elongation, K_IC) are required. | 275 | 370 | 8 | 105 HB | 32 % IACS |
Solution heat treated and overaged (stabilized) | Pick for dimensional stability, elevated-temperature service and improved resistance to stress-corrosion cracking, at some loss of peak strength. | 295 | 350 | 5 | 105 HB | 35 % IACS |
Solution heat treated and artificially aged | Choose when maximum yield strength and hardness are needed and reduced ductility/toughness is acceptable. | 320 | 390 | 3 | 115 HB | 33 % IACS |
What is EN AC-21000-T4?
EN AC-21000-T4 is EN AC-21000 in the T4 temper — the standard EN 1706 delivery condition: best combination of strength, ductility and toughness for structural aerospace and motorsport castings. EN AC-21000-T4 has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 320 MPa (46.4 ksi) — stronger than 56% of aluminum grades. Elongation at break is 7% and the elastic modulus is 71 GPa (10.3 Msi). EN AC-21000-T4 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 548°C (1,018 °F).
Advantages
- Easy to machine — 78/100, better than 89% of aluminum grades
- Tough — resists crack growth — 32 MPa·√m (29.1 ksi·√in), better than 83% of aluminum grades
Limitations
- Needs corrosion protection — 33/100, worse than 91% of aluminum grades
- Poor heat conductor — 112 W/m·K (64.7 BTU/hr·ft·°F), worse than 86% of aluminum grades
- Limited formability — 10/100, worse than 80% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
EN AC-21000-T4 properties
Typical room-temperature values for EN AC-21000-T4; 12 are specific to this condition. Other listed values are EN AC-21000 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
EN AC-21000-T4 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 548°C (1,018 °F).
Mechanical12
EN AC-21000-T4 has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 320 MPa (46.4 ksi) — stronger than 56% of aluminum grades. Elongation at break is 7% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
EN AC-21000-T4 is rated for continuous service to 150°C (302 °F). It conducts heat at 112 W/m·K (64.7 BTU/hr·ft·°F), worse than 86% of aluminum grades. Thermal expansion is 21 µm/m·K (11.7 µin/in·°F).
Electrical3
EN AC-21000-T4 conducts electricity at 30 % IACS, worse than 73% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (33/100), worse than 91% of aluminum grades.
Sustainability4
Producing a kilogram of EN AC-21000-T4 takes about 205 MJ of energy and emits 13 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 10%.
Manufacturability8
EN AC-21000-T4's machinability is very good (78/100, better than 89% of aluminum grades); weldability poor (25/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with EN AC-21000-T4
Is EN AC-21000 easy to machine?
Machines very well with sharp carbide/PCD tooling, high speed and flood coolant; rough after solution treatment and finish after ageing to control distortion.
Can EN AC-21000 be welded?
Poor fusion weldability — high hot-tearing sensitivity; if repair is unavoidable use TIG with 2319 (Al-6Cu) filler on preheated parts followed by full re-solution + re-age.
Can EN AC-21000 be formed, bent or molded?
Sand, investment and gravity permanent-mould casting only; needs strong directional solidification, generous risering/chills, low Si-Fe virgin metal and tight degassing to avoid hot tears and shrink porosity.
What surface finishes work on EN AC-21000?
Chromate/chromate-free conversion coating plus primer/paint is the usual protection; sulfuric or hard anodizing works but gives dark non-uniform colour, and cladding-free Cu content makes it unsuitable for bright decorative finishes.
EN AC-21000 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 |
|---|---|---|
| Cumain strengthening element (θ'-Al2Cu) | 4.2 – 5 | 4.6 |
| Mg | 0.15 – 0.35 | 0.25 |
| Tigrain refinement | 0.15 – 0.3 | 0.22 |
| Sikept very low to avoid Cu2Mg2Si and loss of ductility | ≤ 0.18 | 0.08 |
| Feimpurity limit | ≤ 0.19 | 0.1 |
| Mn | ≤ 0.1 | 0.05 |
| Ni | ≤ 0.05 | — |
| Zn | ≤ 0.07 | — |
| Pb | ≤ 0.05 | — |
| Sn | ≤ 0.05 | — |
| others (each)total ≤ 0.10 | ≤ 0.03 | — |
| Al | balance | — |
EN AC-21000-T4 — frequently asked
What is EN AC-21000-T4 used for?
EN AC-21000-T4 is typically used for aerospace structural castings, military hardware, high-strength brackets and gearbox housings. In short: highest-strength cast Al-Cu; aerospace sand-casting alloy; difficult to cast.
What is the yield strength of EN AC-21000-T4?
EN AC-21000-T4 has a typical yield strength of 210 MPa (30.5 ksi) and a tensile strength of 320 MPa (46.4 ksi) — stronger than 56% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is EN AC-21000-T4 easy to machine?
Yes — machinability is rated very good (78/100, better than 89% of aluminum grades). Machines very well with sharp carbide/PCD tooling, high speed and flood coolant; rough after solution treatment and finish after ageing to control distortion.
Can EN AC-21000-T4 be welded?
Not readily — weldability is rated poor (25/100). Poor fusion weldability — high hot-tearing sensitivity; if repair is unavoidable use TIG with 2319 (Al-6Cu) filler on preheated parts followed by full re-solution + re-age.
What surface finishes work on EN AC-21000-T4?
Chromate/chromate-free conversion coating plus primer/paint is the usual protection; sulfuric or hard anodizing works but gives dark non-uniform colour, and cladding-free Cu content makes it unsuitable for bright decorative finishes.
Can EN AC-21000-T4 be formed, bent or molded?
Sand, investment and gravity permanent-mould casting only; needs strong directional solidification, generous risering/chills, low Si-Fe virgin metal and tight degassing to avoid hot tears and shrink porosity.
What is the maximum service temperature of EN AC-21000-T4?
EN AC-21000-T4 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 EN AC-21000-T4 and EN AC-21000-F?
T4 is the default condition — the standard EN 1706 delivery condition: best combination of strength, ductility and toughness for structural aerospace and motorsport castings. F: rarely used commercially; only for non-structural parts or as the delivery state before customer heat treatment. Yield strength is 210 MPa in T4 versus 95 MPa in F.
Sources
- EN 1706 — Aluminium and aluminium alloys, castings, chemical composition and mechanical properties — CEN (2020)
- DIN 1725-2 G-AlCu4TiMg (3.1371) — DIN (1986)
- GB/T 1173 (ZL201/ZAlCu5Mn) — SAC (2013)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol. 15 — Casting — ASM International (2008)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
- ASTM B26/B26M — Aluminum-Alloy Sand Castings (201.0/A201.0) — ASTM (2018)
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.