Aluminum 222.0-O (Annealed)
Temper
AA 222.0 · UNS A02220
Pick when maximum dimensional stability and lowest residual stress matter more than strength.
Values for the O condition
Other 222.0 tempers and conditions
222.0 is listed in 4 conditions; see the grade overview at 222.0.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OThis page Annealed | Pick when maximum dimensional stability and lowest residual stress matter more than strength. | 138 | 186 | 1 | 80 HB | 38 % IACS |
Permanent mold cast, stabilized | Permanent-mold condition without solution treatment — good hardness with better dimensional stability and lower distortion risk. | 241 | 255 | 0.5 | 115 HB | 35 % IACS |
T61Default T6 variant, underaged | Standard sand-cast condition: highest strength/hardness combination normally supplied for 222.0. | 275 | 283 | 0.5 | 115 HB | 33 % IACS |
Permanent mold cast, solution heat treated and fully artificially aged | Highest strength and hardness available in 222.0 — choose for wear/bearing surfaces where near-zero ductility is acceptable. | 331 | 331 | 0.5 | 140 HB | 31 % IACS |
What is 222.0-O?
222.0-O is 222.0 in the O temper — pick when maximum dimensional stability and lowest residual stress matter more than strength. 222.0-O has a yield strength of 138 MPa (20 ksi) and a tensile strength of 186 MPa (27 ksi) — weaker than 71% of aluminum grades. Elongation at break is 1% and the elastic modulus is 74 GPa (10.7 Msi). 222.0-O has a density of 2.95 g/cm³ (0.107 lb/in³), heavier than 99% of aluminum grades. It melts at 521°C (970 °F). T61 is the default condition FabDigit quotes; O is available on request or by drawing note.
Advantages
- High service temperature — 230°C (446 °F), better than 95% of aluminum grades
Limitations
- Needs corrosion protection — 25/100, worse than 100% of aluminum grades
- Limited ductility — 1%, worse than 95% of aluminum grades
- Difficult to weld — 20/100, worse than 89% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
222.0-O properties
Typical room-temperature values for 222.0-O; 10 are specific to this condition. Other listed values are 222.0 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
222.0-O has a density of 2.95 g/cm³ (0.107 lb/in³), heavier than 99% of aluminum grades. It melts at 521°C (970 °F).
Mechanical10
222.0-O has a yield strength of 138 MPa (20 ksi) and a tensile strength of 186 MPa (27 ksi) — weaker than 71% of aluminum grades. Elongation at break is 1% and the elastic modulus is 74 GPa (10.7 Msi).
Thermal6
222.0-O is rated for continuous service to 230°C (446 °F). It conducts heat at 138 W/m·K (79.7 BTU/hr·ft·°F), worse than 55% of aluminum grades. Thermal expansion is 22.6 µm/m·K (12.6 µin/in·°F).
Electrical3
222.0-O conducts electricity at 38 % IACS, better than 61% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), worse than 100% of aluminum grades.
Sustainability4
Producing a kilogram of 222.0-O takes about 200 MJ of energy and emits 12.5 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 50%.
Manufacturability6
222.0-O's machinability is very good (70/100, better than 72% of aluminum grades); weldability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 222.0-O
Is 222.0 easy to machine?
Machines very well with sharp carbide tools and light lubrication; hard CuAl2 phase gives short, easily broken chips and good surface finish.
Can 222.0 be welded?
Poor fusion weldability — high Cu promotes hot cracking and loss of aged strength; repair by brazing/adhesive or mechanical fastening where possible.
Can 222.0 be formed, bent or molded?
Casting only, no cold forming; low fluidity and high hot-tear sensitivity demand generous fillets, chills and well-fed risers, plus careful post-cast heat treatment to avoid distortion.
What surface finishes work on 222.0?
Do not rely on anodizing (dark, non-protective); use chromate/phosphate conversion, primer + paint or plating, and avoid galvanic couples with steel or copper in humid service.
222.0 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 | ≤ 2 | 1 |
| Feimpurity limit | ≤ 1.5 | 0.8 |
| Cuprincipal strengthening element | 9.2 – 10.7 | 10 |
| Mn | ≤ 0.5 | — |
| Mgaids age hardening | 0.15 – 0.35 | 0.25 |
| Ni | ≤ 0.5 | — |
| Zn | ≤ 0.8 | — |
| Tigrain refiner | ≤ 0.25 | — |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.35 | — |
| Al | balance | — |
222.0-O — frequently asked
What is 222.0-O used for?
222.0-O is typically used for cylinder heads (legacy), engine brackets and high-hardness machinery parts. In short: highest-hardness Al-Cu casting; very low ductility; legacy permanent-mold alloy.
What is the yield strength of 222.0-O?
222.0-O has a typical yield strength of 138 MPa (20 ksi) and a tensile strength of 186 MPa (27 ksi) — weaker than 71% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 222.0-O easy to machine?
Yes — machinability is rated very good (70/100, better than 72% of aluminum grades). Machines very well with sharp carbide tools and light lubrication; hard CuAl2 phase gives short, easily broken chips and good surface finish.
Can 222.0-O be welded?
Not readily — weldability is rated poor (20/100). Poor fusion weldability — high Cu promotes hot cracking and loss of aged strength; repair by brazing/adhesive or mechanical fastening where possible.
What surface finishes work on 222.0-O?
Do not rely on anodizing (dark, non-protective); use chromate/phosphate conversion, primer + paint or plating, and avoid galvanic couples with steel or copper in humid service.
Can 222.0-O be formed, bent or molded?
Casting only, no cold forming; low fluidity and high hot-tear sensitivity demand generous fillets, chills and well-fed risers, plus careful post-cast heat treatment to avoid distortion.
What is the maximum service temperature of 222.0-O?
222.0-O is rated for continuous use to about 230°C (446 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 222.0-T61 and 222.0-O?
T61 is the default condition — standard sand-cast condition: highest strength/hardness combination normally supplied for 222.0. O: pick when maximum dimensional stability and lowest residual stress matter more than strength. Yield strength is 275 MPa in T61 versus 138 MPa in O.
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)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
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.