Aluminum A390 · temper
Aluminum A390-T7
Properties of the T7 condition, compared with the other A390 tempers.
Choose when dimensional stability and property retention at 150–230 °C matter more than peak strength.
What is A390-T7?
A390-T7 is A390 in the T7 temper — choose when dimensional stability and property retention at 150–230 °C matter more than peak strength. A390-T7 has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 250 MPa (36.3 ksi) — stronger than 62% of aluminum grades. Elongation at break is 1% and the elastic modulus is 81 GPa (11.7 Msi). A390-T7 has a density of 2.73 g/cm³ (0.0986 lb/in³), heavier than 61% of aluminum grades. It melts at 507°C (945 °F).
Advantages
- Stiff — 81 GPa (11.7 Msi), better than 96% of aluminum grades
- High service temperature — 230°C (446 °F), better than 95% of aluminum grades
Limitations
- Limited formability — 3/100, worse than 100% of aluminum grades
- Low fracture toughness — 12 MPa·√m (10.9 ksi·√in), worse than 99% of aluminum grades
- Limited ductility — 1%, worse than 95% of aluminum grades
- Hard to polish — 40/100, worse than 90% of aluminum grades
- Difficult to machine — 31/100, worse than 89% of aluminum grades
A390-T7 properties
Typical room-temperature values for A390-T7 — 9 properties are specific to this condition; the rest are grade-level values shared by every A390 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
A390-T7 has a density of 2.73 g/cm³ (0.0986 lb/in³), heavier than 61% of aluminum grades. It melts at 507°C (945 °F).
Mechanical14
A390-T7 has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 250 MPa (36.3 ksi) — stronger than 62% of aluminum grades. Elongation at break is 1% and the elastic modulus is 81 GPa (11.7 Msi).
Thermal6
A390-T7 is rated for continuous service to 230°C (446 °F). It conducts heat at 142 W/m·K (82 BTU/hr·ft·°F), better than 51% of aluminum grades. Thermal expansion is 18 µm/m·K (10 µin/in·°F).
Electrical3
A390-T7 conducts electricity at 28 % IACS, worse than 82% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (42/100), worse than 69% of aluminum grades.
Sustainability4
Producing a kilogram of A390-T7 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 55%.
Manufacturability8
A390-T7's machinability is poor (31/100, worse than 89% of aluminum grades); weldability poor (20/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other A390 tempers and conditions
A390 is also supplied in 3 other conditions. The full side-by-side table is on the A390 overview.
- T6Pick for maximum hardness and strength on permanent-mould/low-pressure castings, e.g. pistons and pump bodies.275 MPa yield · 145 HB
- FStandard high-volume condition: die-cast A390/B390 parts used as-cast for wear surfaces and thin-wall housings.240 MPa yield · 120 HB
- T7Choose when dimensional stability and property retention at 150–230 °C matter more than peak strength.240 MPa yield · 125 HB
- T5Low-cost stabilising age of permanent-mould or die castings to relieve stress and steady dimensions with a small strength gain.195 MPa yield · 110 HB
Working with A390-T7
Is A390 easy to machine?
Highly abrasive primary Si — use PCD or diamond-coated tooling, high speed / light feed, copious coolant; carbide life is very short and honed bores need diamond stones.
Can A390 be welded?
Essentially not weldable for structural joints (hot cracking, Cu content, gas porosity); repair only by TIG with 4145/4047 filler on non-critical areas.
Can A390 be formed, bent or molded?
Die casting or permanent-mould casting only; melt at 730–790 °C with phosphorus refinement and controlled cooling to keep primary Si fine and dispersed — no cold forming.
What surface finishes work on A390?
Hard-anodize (Type III) for bore wear surfaces, otherwise chromate/phosphate conversion or paint; decorative anodizing and bright polishing look grey and blotchy from the Si phase.
A390 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 |
|---|---|---|
| Siprimary silicon crystals give wear resistance | 16 – 18 | 17 |
| Cu | 4 – 5 | 4.5 |
| Mg | 0.45 – 0.65 | 0.55 |
| FeA390.0 limit; 390.0/B390.0 allow up to 1.3 | ≤ 0.5 | 0.3 |
| MnB390.0 allows 0.50 | ≤ 0.1 | — |
| ZnB390.0 allows 1.5 | ≤ 0.1 | — |
| Ti | ≤ 0.2 | — |
| NiB390.0 limit | ≤ 0.1 | — |
| Padded as refiner for primary Si (not always a spec element) | 0 – 0.01 | 0.01 |
| Others (each)total 0.20 max | ≤ 0.1 | — |
| Al | balance | — |
A390-T7 — frequently asked
What is A390-T7 used for?
A390-T7 is typically used for linerless engine cylinder blocks, compressor pistons, air-conditioning compressor bodies, pistons and wear sleeves, pump housings with abrasive service and small-engine cylinders. In short: hypereutectic Al-Si wear cast.
What is the yield strength of A390-T7?
A390-T7 has a typical yield strength of 240 MPa (34.8 ksi) and a tensile strength of 250 MPa (36.3 ksi) — stronger than 62% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is A390-T7 easy to machine?
Not especially — machinability is rated poor (31/100, worse than 89% of aluminum grades). Highly abrasive primary Si — use PCD or diamond-coated tooling, high speed / light feed, copious coolant; carbide life is very short and honed bores need diamond stones.
Can A390-T7 be welded?
Not readily — weldability is rated poor (20/100). Essentially not weldable for structural joints (hot cracking, Cu content, gas porosity); repair only by TIG with 4145/4047 filler on non-critical areas.
What surface finishes work on A390-T7?
Hard-anodize (Type III) for bore wear surfaces, otherwise chromate/phosphate conversion or paint; decorative anodizing and bright polishing look grey and blotchy from the Si phase.
Can A390-T7 be formed, bent or molded?
Die casting or permanent-mould casting only; melt at 730–790 °C with phosphorus refinement and controlled cooling to keep primary Si fine and dispersed — no cold forming.
What is the maximum service temperature of A390-T7?
A390-T7 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.
Can FabDigit make parts in A390-T7?
Yes — A390-T7 is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot (Pink/Teal Sheets) — The Aluminum Association (2018)
- ASTM B85 / B108 — Aluminum-Alloy Die Castings and Permanent Mold Castings — ASTM (2018)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (390.0/A390.0/B390.0 data) — ASM International (1990)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- Hypereutectic Al-Si die casting alloy datasheets (engine block / compressor applications) — Foundry alloy producers (2020)
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.