Aluminum 390 · temper
Aluminum 390-T7
Properties of the T7 condition, compared with the other 390 tempers.
Overaged/stabilised temper chosen when dimensional stability at elevated temperature matters more than peak strength (compressor and engine components).
What is 390-T7?
390-T7 is 390 in the T7 temper — overaged/stabilised temper chosen when dimensional stability at elevated temperature matters more than peak strength (compressor and engine components). 390-T7 has a yield strength of 262 MPa (38 ksi) and a tensile strength of 262 MPa (38 ksi) — stronger than 68% of aluminum grades. Elongation at break is 1% and the elastic modulus is 81 GPa (11.7 Msi). 390-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 — 200°C (392 °F), better than 90% of aluminum grades
Limitations
- Limited formability — 3/100, worse than 100% of aluminum grades
- Limited ductility — 1%, worse than 95% of aluminum grades
- Low fracture toughness — 15 MPa·√m (13.7 ksi·√in), worse than 93% of aluminum grades
- Hard to polish — 40/100, worse than 90% of aluminum grades
- Difficult to machine — 32/100, worse than 88% of aluminum grades
390-T7 properties
Typical room-temperature values for 390-T7 — 9 properties are specific to this condition; the rest are grade-level values shared by every 390 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
390-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).
Mechanical12
390-T7 has a yield strength of 262 MPa (38 ksi) and a tensile strength of 262 MPa (38 ksi) — stronger than 68% of aluminum grades. Elongation at break is 1% and the elastic modulus is 81 GPa (11.7 Msi).
Thermal6
390-T7 is rated for continuous service to 200°C (392 °F). It conducts heat at 138 W/m·K (79.7 BTU/hr·ft·°F), worse than 55% of aluminum grades. Thermal expansion is 18 µm/m·K (10 µin/in·°F).
Electrical3
390-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 390-T7 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 70%.
Manufacturability8
390-T7's machinability is poor (32/100, worse than 88% of aluminum grades); weldability poor (22/100); 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 390 tempers and conditions
390 is also supplied in 3 other conditions. The full side-by-side table is on the 390 overview.
- T6Maximum strength and hardness condition for permanent-mold/sand A390 wear parts; ductility remains essentially nil.310 MPa yield · 145 HB
- T7Overaged/stabilised temper chosen when dimensional stability at elevated temperature matters more than peak strength (compressor and engine components).262 MPa yield · 120 HB
- FStandard stocked condition for as-cast wear parts and engine blocks; highest as-cast strength comes from the die-cast (B390) route.241 MPa yield · 120 HB
- T5Low-distortion stabilising age used on permanent-mold A390 castings to raise hardness and dimensional stability without full solution treatment.200 MPa yield · 110 HB
Working with 390-T7
Is 390 easy to machine?
Treat as an abrasive metal-matrix composite: PCD or diamond-coated tooling, high speed / light feed, flood coolant; carbide edges wear in minutes.
Can 390 be welded?
Poor — high Cu plus coarse primary Si makes it hot-crack sensitive; repair only by TIG with 4145/4047 filler and preheat, avoid structural welds.
Can 390 be formed, bent or molded?
Die casting (B390) or permanent-mold/sand casting only; needs superheat above ~760 °C and phosphorus refinement to keep primary Si fine, plus hardened tooling for melt handling.
What surface finishes work on 390?
Anodising is dull and patchy; typical practice is precision honing to expose silicon for bore wear surfaces, or chemical/organic coatings and mechanical plating for corrosion protection.
390 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 particles give the wear resistance and low CTE | 16 – 18 | 17 |
| Cu | 4 – 5 | 4.5 |
| Mg | 0.45 – 0.65 | 0.55 |
| FeA390.0 limits Fe to 0.50 max | ≤ 1.3 | — |
| MnB390.0 allows 0.50 max | ≤ 0.1 | — |
| ZnB390.0 allows 1.5 max | ≤ 0.1 | — |
| Ti | ≤ 0.2 | — |
| NiB390.0 | ≤ 0.1 | — |
| SnB390.0 | ≤ 0.1 | — |
| Others (each)total 0.20 max | ≤ 0.1 | — |
| Al | balance | — |
390-T7 — frequently asked
What is 390-T7 used for?
390-T7 is typically used for cylinder blocks, compressor parts and pumps. In short: hypereutectic wear cast.
What is the yield strength of 390-T7?
390-T7 has a typical yield strength of 262 MPa (38 ksi) and a tensile strength of 262 MPa (38 ksi) — stronger than 68% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 390-T7 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 88% of aluminum grades). Treat as an abrasive metal-matrix composite: PCD or diamond-coated tooling, high speed / light feed, flood coolant; carbide edges wear in minutes.
Can 390-T7 be welded?
Not readily — weldability is rated poor (22/100). Poor — high Cu plus coarse primary Si makes it hot-crack sensitive; repair only by TIG with 4145/4047 filler and preheat, avoid structural welds.
What surface finishes work on 390-T7?
Anodising is dull and patchy; typical practice is precision honing to expose silicon for bore wear surfaces, or chemical/organic coatings and mechanical plating for corrosion protection.
Can 390-T7 be formed, bent or molded?
Die casting (B390) or permanent-mold/sand casting only; needs superheat above ~760 °C and phosphorus refinement to keep primary Si fine, plus hardened tooling for melt handling.
What is the maximum service temperature of 390-T7?
390-T7 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 390-T7?
Yes — 390-T7 is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B85/B85M – Aluminum-Alloy Die Castings — ASTM International (2021)
- ASTM B108/B108M – Aluminum-Alloy Permanent Mold Castings — ASTM International (2019)
- Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot (Pink Sheets) — The Aluminum Association (2018)
- 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.