Aluminum A242.0-T77
Temper
AA A242.0 · UNS A12420
T77 = solution heat treated and fully overaged
Pick for parts that run hottest and longest — lowest growth and best residual-stress relief, at reduced strength.
Values for the T77 condition
Other A242.0 tempers and conditions
A242.0 is listed in 7 conditions; see the grade overview at A242.0.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Raw casting before any thermal treatment; used only as an intermediate state or for non-structural parts. | 105 | 165 | 1.5 | 65 HB | 33 % IACS |
Annealed | Choose when maximum dimensional stability and lowest residual stress matter more than strength. | 124 | 186 | 1 | 70 HB | 44 % IACS |
Annealed / partially solution treated and stabilised | Soft, highly stable condition used where machining accuracy and freedom from growth outweigh strength. | 124 | 186 | 1.5 | 70 HB | 42 % IACS |
T75Default Solution heat treated and overaged/stabilised | Standard supply condition for A242.0: balanced strength with dimensional stability and creep resistance at 200–260 °C. | 145 | 214 | 2 | 75 HB | 36 % IACS |
T77This page Solution heat treated and fully overaged | Pick for parts that run hottest and longest — lowest growth and best residual-stress relief, at reduced strength. | 159 | 207 | 2 | 75 HB | 38 % IACS |
As-cast then artificially aged | Low-distortion route: no solution treatment, good stability and hardness for cylinder heads and pistons. | 207 | 221 | 0.7 | 90 HB | 34 % IACS |
T6 variant, underaged | Highest room-temperature strength and hardness, mainly on permanent-mold castings; ductility is minimal. | 234 | 276 | 0.5 | 105 HB | 33 % IACS |
What is A242.0-T77?
A242.0-T77 is A242.0 in the T77 temper — pick for parts that run hottest and longest — lowest growth and best residual-stress relief, at reduced strength. A242.0-T77 has a yield strength of 159 MPa (23.1 ksi) and a tensile strength of 207 MPa (30 ksi) — weaker than 62% of aluminum grades. Elongation at break is 2% and the elastic modulus is 71 GPa (10.3 Msi). A242.0-T77 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). T75 is the default condition FabDigit quotes; T77 is available on request or by drawing note.
Advantages
- High service temperature — 300°C (572 °F), better than 99% of aluminum grades
Limitations
- Limited ductility — 2%, worse than 87% of aluminum grades
- Needs corrosion protection — 35/100, worse than 85% of aluminum grades
- Difficult to weld — 22/100, worse than 83% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
A242.0-T77 properties
Typical room-temperature values for A242.0-T77; 11 are specific to this condition. Other listed values are A242.0 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
A242.0-T77 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).
Mechanical11
A242.0-T77 has a yield strength of 159 MPa (23.1 ksi) and a tensile strength of 207 MPa (30 ksi) — weaker than 62% of aluminum grades. Elongation at break is 2% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
A242.0-T77 is rated for continuous service to 300°C (572 °F). It conducts heat at 148 W/m·K (85.5 BTU/hr·ft·°F), better than 56% of aluminum grades. Thermal expansion is 22.5 µm/m·K (12.5 µin/in·°F).
Electrical3
A242.0-T77 conducts electricity at 38 % IACS, better than 61% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (35/100), worse than 85% of aluminum grades.
Sustainability4
Producing a kilogram of A242.0-T77 takes about 200 MJ of energy and emits 12.5 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 25%.
Manufacturability7
A242.0-T77's machinability is good (60/100, worse than 51% of aluminum grades); weldability poor (22/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A242.0-T77
Is A242.0 easy to machine?
Machines well with sharp carbide tooling and high speeds; Al₃Ni and Al₂Cu particles are abrasive, so use PCD for long runs and flood coolant to avoid built-up edge.
Can A242.0 be welded?
Essentially non-weldable by fusion for structural joints — high Cu content causes hot cracking; repair only by qualified foundry weld procedures followed by re-heat treatment.
Can A242.0 be formed, bent or molded?
Sand and permanent-mold casting only; fluidity is fair and the alloy is hot-tear sensitive, so use generous fillets, chills and directional-solidification gating.
What surface finishes work on A242.0?
Anodizing gives dark, non-decorative films; specify chromate conversion plus primer/paint for corrosion protection, or hard anodize/plating for wear surfaces.
A242.0 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 | ≤ 0.6 | 0.3 |
| Feimpurity limit | ≤ 0.8 | 0.4 |
| Cuprimary strengthener (Al₂Cu) | 3.7 – 4.5 | 4.1 |
| Mn | ≤ 0.1 | 0.05 |
| Mgwith Cu forms S-phase | 1.2 – 1.8 | 1.5 |
| Crdispersoid former, thermal stability | 0.15 – 0.25 | 0.2 |
| NiAl₃Ni for hot strength | 1.8 – 2.3 | 2 |
| Zn | ≤ 0.1 | 0.03 |
| Tigrain refiner | 0.07 – 0.2 | 0.12 |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
A242.0-T77 — frequently asked
What is A242.0-T77 used for?
A242.0-T77 is typically used for cylinder heads, pistons, engine covers and aerospace elevated-temperature parts. In short: best hot-strength cast aluminum; 260 °C service capability; low ductility, not weldable.
What is the yield strength of A242.0-T77?
A242.0-T77 has a typical yield strength of 159 MPa (23.1 ksi) and a tensile strength of 207 MPa (30 ksi) — weaker than 62% of aluminum grades. Strength varies by condition: see the 7 listed tempers.
Is A242.0-T77 easy to machine?
Reasonably — machinability is rated good (60/100, worse than 51% of aluminum grades). Machines well with sharp carbide tooling and high speeds; Al₃Ni and Al₂Cu particles are abrasive, so use PCD for long runs and flood coolant to avoid built-up edge.
Can A242.0-T77 be welded?
Not readily — weldability is rated poor (22/100). Essentially non-weldable by fusion for structural joints — high Cu content causes hot cracking; repair only by qualified foundry weld procedures followed by re-heat treatment.
What surface finishes work on A242.0-T77?
Anodizing gives dark, non-decorative films; specify chromate conversion plus primer/paint for corrosion protection, or hard anodize/plating for wear surfaces.
Can A242.0-T77 be formed, bent or molded?
Sand and permanent-mold casting only; fluidity is fair and the alloy is hot-tear sensitive, so use generous fillets, chills and directional-solidification gating.
What is the maximum service temperature of A242.0-T77?
A242.0-T77 is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A242.0-T75 and A242.0-T61?
T75 is the default condition — standard supply condition for A242.0: balanced strength with dimensional stability and creep resistance at 200–260 °C. T61: highest room-temperature strength and hardness, mainly on permanent-mold castings; ductility is minimal. Yield strength is 145 MPa in T75 versus 234 MPa in T61.
Sources
- Registration Record of International Alloy Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot (Pink Sheets) — The Aluminum Association (2019)
- 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 and Special-Purpose Materials — ASM International (1990)
- ASM Specialty Handbook — Aluminum and Aluminum Alloys — ASM International (1993)
- ASM Handbook Vol. 15 — Casting — ASM International (2008)
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.