Aluminum 242.0
AA 242.0 · UNS A02420 · also CN42A
242.0 (UNS A02420, CN42A) is an Al-Cu-Ni-Mg heat-resistant casting alloy in the ANSI/AA 2xx.x family, where nickel and magnesium additions retain strength at elevated temperature.
Reference datasheet — 242.0 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 T5 condition
242.0 tempers and conditions
242.0 is supplied in 5 conditions, soft to hard. T5 is the default FabDigit quotes; the values on this page are for it.
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 |
T5Default 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?
242.0 (UNS A02420, CN42A) is an Al-Cu-Ni-Mg heat-resistant casting alloy in the ANSI/AA 2xx.x family, where nickel and magnesium additions retain strength at elevated temperature. Available in O, T2, T5, T61 and T7 tempers, it has been used for engine pistons and cylinder heads; the reference condition gives 207 MPa yield, 221 MPa tensile, 85 HB, 130 W/m·K thermal conductivity, 34% IACS and a maximum service temperature of 250 °C. Elongation is only 0.5%, so the alloy tolerates no forming and little impact loading, and the high copper makes it effectively non-weldable. 242.0 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). 242.0 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).
What is 242.0 used for?
- engine pistons
- cylinder heads
- high-temperature castings
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 properties
Typical room-temperature values for 242.0-T5; bars are the position among aluminum grades.
Physical3
242.0 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 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 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 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 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'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. 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. 242.0 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 242.0
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.
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 |
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.
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 242.0 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- A02420
- Trade names
- CN42A
How much does 242.0 cost?
242.0 is a standard-cost aluminum ($$), cheaper than about 71% 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.
242.0 — frequently asked
What is 242.0 used for?
242.0 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?
242.0 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 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 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?
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 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?
242.0 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.
How much does 242.0 cost?
242.0 is a standard-cost aluminum ($$), cheaper than about 71% 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
- 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; 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.