Aluminum ZL109-T7
Temper
GB ZL109 · EN AC-48000 · JIS AC8B
T7 = solution heat treated and overaged (stabilized)
Overaged/stabilised for maximum dimensional and thermal stability when the part runs continuously above 250 °C; trades ~10 % strength for creep and growth resistance.
Values for the T7 condition
Other ZL109 tempers and conditions
ZL109 is listed in 5 conditions; see the grade overview at ZL109.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Untreated as-cast condition; used for low-duty castings or as the starting point before heat treatment. | 150 | 190 | 0.8 | 90 HB | 29 % IACS |
Cooled from hot working and naturally aged | Simple ageing without solution treatment — the low-cost GB/T 1173 condition for mass-produced pistons where dimensional stability matters more than peak strength. | 180 | 215 | 0.6 | 100 HB | 28 % IACS |
Cooled from hot working and artificially aged | Short low-temperature age used by some piston makers to raise hardness quickly while keeping distortion to a minimum. | 190 | 225 | 0.6 | 105 HB | 28 % IACS |
T7This page Solution heat treated and overaged (stabilized) | Overaged/stabilised for maximum dimensional and thermal stability when the part runs continuously above 250 °C; trades ~10 % strength for creep and growth resistance. | 195 | 235 | 1 | 105 HB | 30 % IACS |
T6Default Solution heat treated and artificially aged | Peak-strength condition (GB/T 1173 JT6) for high-load petrol and diesel pistons and other hot-running castings. | 225 | 265 | 0.8 | 115 HB | 27 % IACS |
What is ZL109-T7?
ZL109-T7 is ZL109 in the T7 temper — overaged/stabilised for maximum dimensional and thermal stability when the part runs continuously above 250 °C; trades ~10 % strength for creep and growth resistance. ZL109-T7 has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 235 MPa (34.1 ksi) — stronger than 51% of aluminum grades. Elongation at break is 1% and the elastic modulus is 80 GPa (11.6 Msi). ZL109-T7 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 525°C (977 °F). T6 is the default condition FabDigit quotes; T7 is available on request or by drawing note.
Advantages
- High service temperature — 300°C (572 °F), better than 99% of aluminum grades
- Stiff — 80 GPa (11.6 Msi), better than 95% of aluminum grades
- Low embodied carbon — 10.5 kg CO₂/kg, better than 95% of aluminum grades
Limitations
- Limited ductility — 1%, worse than 95% of aluminum grades
- Low fracture toughness — 16 MPa·√m (14.6 ksi·√in), worse than 89% of aluminum grades
- Limited formability — 6/100, worse than 89% of aluminum grades
ZL109-T7 properties
Typical room-temperature values for ZL109-T7; 22 are specific to this condition. Other listed values are ZL109 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
ZL109-T7 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 525°C (977 °F).
Mechanical12
ZL109-T7 has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 235 MPa (34.1 ksi) — stronger than 51% of aluminum grades. Elongation at break is 1% and the elastic modulus is 80 GPa (11.6 Msi).
Thermal6
ZL109-T7 is rated for continuous service to 300°C (572 °F). It conducts heat at 135 W/m·K (78 BTU/hr·ft·°F), worse than 58% of aluminum grades. Thermal expansion is 19.5 µm/m·K (10.8 µin/in·°F).
Electrical3
ZL109-T7 conducts electricity at 30 % IACS, worse than 73% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (43/100), worse than 65% of aluminum grades.
Sustainability4
Producing a kilogram of ZL109-T7 takes about 150 MJ of energy and emits 10.5 kg of CO₂ — less than 97% of aluminum grades. Typical recycled content is 35%.
Manufacturability7
ZL109-T7's machinability is fair (48/100, worse than 68% of aluminum grades); weldability poor (32/100); formability not recommended (6/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ZL109-T7
Is ZL109 easy to machine?
Machinable with PCD or diamond-coated carbide only — the eutectic Si is highly abrasive; use high speed, light feed and flood coolant, and expect short tool life with plain carbide.
Can ZL109 be welded?
Poor weldability: Cu + Mg promote hot cracking and porosity; if repair is unavoidable use TIG with 4047 (Al-12Si) filler, preheat 150–200 °C and re-age afterwards.
Can ZL109 be formed, bent or molded?
Permanent-mould (metal mould) gravity casting is standard; excellent fluidity and low shrinkage, but degas the melt and P-modify to refine primary/eutectic Si and avoid coarse Ni-Fe phases.
What surface finishes work on ZL109?
Hard anodising (Type III) on crowns and ring grooves for wear; decorative anodising is dark and mottled, so shot blasting, tin/graphite coating or phosphating are the usual surface treatments.
ZL109 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 |
|---|---|---|
| Sieutectic Si, usually P-modified | 11 – 13 | 12 |
| Cu | 0.5 – 1.5 | 1 |
| Mg | 0.8 – 1.3 | 1 |
| Niforms thermally stable aluminides | 0.8 – 1.5 | 1.1 |
| Feimpurity limit | ≤ 0.7 | — |
| Mnimpurity limit | ≤ 0.2 | — |
| Tiimpurity limit | ≤ 0.2 | — |
| Znimpurity limit | ≤ 0.2 | — |
| Others (total)total impurities, GB/T 1173 | ≤ 1 | — |
| Al | balance | — |
ZL109-T7 — frequently asked
What is ZL109-T7 used for?
ZL109-T7 is typically used for high-performance engine pistons, diesel engine pistons, reciprocating compressor pistons, air-conditioning compressor components, cylinder liners and ring carriers and wear-resistant bushings and guides. In short: ni-strengthened piston alloy; highest hot hardness, 115 HB; abrasive, needs PCD tooling.
What is the yield strength of ZL109-T7?
ZL109-T7 has a typical yield strength of 195 MPa (28.3 ksi) and a tensile strength of 235 MPa (34.1 ksi) — stronger than 51% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is ZL109-T7 easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 68% of aluminum grades). Machinable with PCD or diamond-coated carbide only — the eutectic Si is highly abrasive; use high speed, light feed and flood coolant, and expect short tool life with plain carbide.
Can ZL109-T7 be welded?
Not readily — weldability is rated poor (32/100). Poor weldability: Cu + Mg promote hot cracking and porosity; if repair is unavoidable use TIG with 4047 (Al-12Si) filler, preheat 150–200 °C and re-age afterwards.
What surface finishes work on ZL109-T7?
Hard anodising (Type III) on crowns and ring grooves for wear; decorative anodising is dark and mottled, so shot blasting, tin/graphite coating or phosphating are the usual surface treatments.
Can ZL109-T7 be formed, bent or molded?
Permanent-mould (metal mould) gravity casting is standard; excellent fluidity and low shrinkage, but degas the melt and P-modify to refine primary/eutectic Si and avoid coarse Ni-Fe phases.
What is the maximum service temperature of ZL109-T7?
ZL109-T7 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 ZL109-T6 and ZL109-F?
T6 is the default condition — peak-strength condition (GB/T 1173 JT6) for high-load petrol and diesel pistons and other hot-running castings. F: untreated as-cast condition; used for low-duty castings or as the starting point before heat treatment. Yield strength is 225 MPa in T6 versus 150 MPa in F.
Sources
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (339.0, 336.0) — ASM International (1990)
- JIS H5202 — Aluminium alloy castings (AC8B) — JSA (2010)
- Aluminum Association Pink Sheets — Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot — The Aluminum Association (2018)
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.