Aluminum 242.0-T5
Temper · default condition
AA 242.0 · UNS A02420 · also CN42A
T5 = cooled from hot working and artificially aged
The standard piston/cylinder-head condition: good hot strength and stability without a solution quench, so distortion risk is low.
Values for the T5 condition
Other 242.0 tempers and conditions
242.0 is listed in 5 conditions; see the grade overview at 242.0.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick when maximum dimensional stability and the little ductility this alloy can offer matter more than strength. | 124 | 186 | 1 | 70 HB | 36 % IACS |
Cooled from hot working, cold worked and naturally aged | Low-strength stabilized condition used when castings must be stress-relieved and dimensionally stable in service. | 124 | 186 | 1 | 70 HB | 36 % IACS |
Solution heat treated and overaged (stabilized) | Overaged condition chosen for aircraft-type cylinder heads: best combination of dimensional stability, thermal conductivity and residual ductility at temperature. | 159 | 207 | 2 | 75 HB | 38 % IACS |
T5DefaultThis page Cooled from hot working and artificially aged | The standard piston/cylinder-head condition: good hot strength and stability without a solution quench, so distortion risk is low. | 207 | 221 | 0.5 | 85 HB | 34 % IACS |
T6 variant, underaged | Highest-strength/hardest condition for permanent-mold castings such as heavy-duty pistons and bearing caps; ductility is essentially nil. | 290 | 324 | 0.5 | 110 HB | 33 % IACS |
What is 242.0-T5?
242.0-T5 is 242.0 in the T5 temper — the standard piston/cylinder-head condition: good hot strength and stability without a solution quench, so distortion risk is low. 242.0-T5 has a yield strength of 207 MPa (30 ksi) and a tensile strength of 221 MPa (32.1 ksi) — stronger than 55% of aluminum grades. Elongation at break is 0.5% and the elastic modulus is 71 GPa (10.3 Msi). 242.0-T5 has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 528°C (982 °F).
Advantages
- High service temperature — 250°C (482 °F), better than 97% of aluminum grades
- Easy to machine — 72/100, better than 80% of aluminum grades
Limitations
- Limited ductility — 0.5%, worse than 99% of aluminum grades
- Needs corrosion protection — 32/100, worse than 94% of aluminum grades
- Limited formability — 5/100, worse than 94% of aluminum grades
- Low fracture toughness — 17 MPa·√m (15.5 ksi·√in), worse than 83% of aluminum grades
- Difficult to weld — 22/100, worse than 83% of aluminum grades
242.0-T5 properties
Typical room-temperature values for 242.0-T5; 11 are specific to this condition. Other listed values are 242.0 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
242.0-T5 has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 528°C (982 °F).
Mechanical12
242.0-T5 has a yield strength of 207 MPa (30 ksi) and a tensile strength of 221 MPa (32.1 ksi) — stronger than 55% of aluminum grades. Elongation at break is 0.5% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
242.0-T5 is rated for continuous service to 250°C (482 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 22.5 µm/m·K (12.5 µin/in·°F).
Electrical3
242.0-T5 conducts electricity at 34 % IACS, worse than 52% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), worse than 94% of aluminum grades.
Sustainability4
Producing a kilogram of 242.0-T5 takes about 205 MJ of energy and emits 11.5 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 45%.
Manufacturability7
242.0-T5's machinability is very good (72/100, better than 80% of aluminum grades); weldability poor (22/100); formability not recommended (5/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 242.0-T5
Is 242.0 easy to machine?
Machines cleanly with carbide at high speed and flood coolant; hard Ni/Cu aluminides are abrasive on HSS, and thin walls need light finishing passes because of low ductility.
Can 242.0 be welded?
Effectively non-weldable for structural repair — high Cu causes hot cracking and loss of aged properties; use mechanical joining or specialized repair procedures.
Can 242.0 be formed, bent or molded?
Casting-only alloy with a long freezing range; needs good risering, chills and controlled degassing to avoid shrink porosity, and no cold forming is possible.
What surface finishes work on 242.0?
Protect by chromate conversion plus primer/paint or hard anodize for wear; decorative anodizing gives dark mottled color due to Cu and Ni.
242.0 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 |
|---|---|---|
| Cumain strengthener | 3.5 – 4.5 | 4 |
| Mg | 1.2 – 1.8 | 1.5 |
| Nithermal stability | 1.7 – 2.3 | 2 |
| Siimpurity limit | ≤ 0.7 | — |
| Feimpurity limit | ≤ 1 | — |
| Mn | ≤ 0.35 | — |
| Cr | ≤ 0.25 | — |
| Tigrain refiner | ≤ 0.25 | — |
| Zn | ≤ 0.35 | — |
| Others (each)total 0.15 max | ≤ 0.05 | — |
| Al | balance | — |
242.0-T5 — frequently asked
What is 242.0-T5 used for?
242.0-T5 is typically used for engine pistons, cylinder heads and high-temperature castings. In short: highest service temperature, 250 °C; classic piston casting alloy; very low ductility.
What is the yield strength of 242.0-T5?
242.0-T5 has a typical yield strength of 207 MPa (30 ksi) and a tensile strength of 221 MPa (32.1 ksi) — stronger than 55% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is 242.0-T5 easy to machine?
Yes — machinability is rated very good (72/100, better than 80% of aluminum grades). Machines cleanly with carbide at high speed and flood coolant; hard Ni/Cu aluminides are abrasive on HSS, and thin walls need light finishing passes because of low ductility.
Can 242.0-T5 be welded?
Not readily — weldability is rated poor (22/100). Effectively non-weldable for structural repair — high Cu causes hot cracking and loss of aged properties; use mechanical joining or specialized repair procedures.
What surface finishes work on 242.0-T5?
Protect by chromate conversion plus primer/paint or hard anodize for wear; decorative anodizing gives dark mottled color due to Cu and Ni.
Can 242.0-T5 be formed, bent or molded?
Casting-only alloy with a long freezing range; needs good risering, chills and controlled degassing to avoid shrink porosity, and no cold forming is possible.
What is the maximum service temperature of 242.0-T5?
242.0-T5 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 242.0-T5 and 242.0-O?
T5 is the default condition — the standard piston/cylinder-head condition: good hot strength and stability without a solution quench, so distortion risk is low. O: pick when maximum dimensional stability and the little ductility this alloy can offer matter more than strength. Yield strength is 207 MPa in T5 versus 124 MPa in O.
Sources
- ANSI H35.1 / Aluminum Association Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot (Pink Sheets) — The Aluminum Association (2015)
- ASTM B26/B26M Standard Specification for Aluminum-Alloy Sand Castings — ASTM International (2018)
- ASTM B108/B108M Standard Specification for Aluminum-Alloy Permanent Mold Castings — ASTM International (2019)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- Aluminum: Properties and Physical Metallurgy (ed. J.E. Hatch) — ASM International (1984)
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.