Aluminum ZL203-T7
Temper
GB ZL203
T7 = solution heat treated and overaged (stabilized)
Overaged for dimensional stability and reduced residual stress on parts running warm or requiring tight machining tolerance.
Values for the T7 condition
Other ZL203 tempers and conditions
ZL203 is listed in 5 conditions; see the grade overview at ZL203.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Low-cost as-cast condition for lightly loaded, dimension-stable parts where machinability matters more than strength. | 95 | 150 | 2.5 | 45 HB | 31 % IACS |
T4Default Solution heat treated and naturally aged | Standard supply condition: best combination of strength and ductility/toughness for general engineering castings. | 110 | 215 | 8 | 60 HB | 33 % IACS |
T7This page Solution heat treated and overaged (stabilized) | Overaged for dimensional stability and reduced residual stress on parts running warm or requiring tight machining tolerance. | 150 | 200 | 3 | 68 HB | 37 % IACS |
Cooled from hot working and artificially aged | Choose when higher strength and hardness are needed and 3 % elongation is acceptable. | 155 | 225 | 3 | 70 HB | 35 % IACS |
Solution heat treated and artificially aged | Peak-strength condition used mainly on the ANSI 295.0 equivalent when maximum hardness/wear resistance is required. | 165 | 250 | 5 | 75 HB | 35 % IACS |
What is ZL203-T7?
ZL203-T7 is ZL203 in the T7 temper — overaged for dimensional stability and reduced residual stress on parts running warm or requiring tight machining tolerance. ZL203-T7 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 200 MPa (29 ksi) — weaker than 65% of aluminum grades. Elongation at break is 3% and the elastic modulus is 70 GPa (10.2 Msi). ZL203-T7 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 545°C (1,013 °F). T4 is the default condition FabDigit quotes; T7 is available on request or by drawing note.
Advantages
- Easy to machine — 80/100, better than 92% of aluminum grades
- High service temperature — 175°C (347 °F), better than 83% of aluminum grades
Limitations
- Limited formability — 8/100, worse than 88% of aluminum grades
- Limited ductility — 3%, worse than 79% of aluminum grades
- Needs corrosion protection — 38/100, worse than 79% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
ZL203-T7 properties
Typical room-temperature values for ZL203-T7; 21 are specific to this condition. Other listed values are ZL203 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
ZL203-T7 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 545°C (1,013 °F).
Mechanical12
ZL203-T7 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 200 MPa (29 ksi) — weaker than 65% of aluminum grades. Elongation at break is 3% and the elastic modulus is 70 GPa (10.2 Msi).
Thermal6
ZL203-T7 is rated for continuous service to 175°C (347 °F). It conducts heat at 155 W/m·K (89.6 BTU/hr·ft·°F), better than 71% of aluminum grades. Thermal expansion is 23 µm/m·K (12.8 µin/in·°F).
Electrical3
ZL203-T7 conducts electricity at 37 % IACS, better than 58% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 79% of aluminum grades.
Sustainability4
Producing a kilogram of ZL203-T7 takes about 200 MJ of energy and emits 12.5 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 25%.
Manufacturability8
ZL203-T7's machinability is very good (80/100, better than 92% of aluminum grades); weldability poor (25/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ZL203-T7
Is ZL203 easy to machine?
Excellent — one of the best-machining cast aluminium alloys; use polished-flute carbide or PCD, high speed, low feed, and flood coolant; T5/T6 gives cleaner surfaces than as-cast.
Can ZL203 be welded?
Poor — Al-Cu is highly hot-crack sensitive; repair-weld only with 4043/2319 filler, low heat input and preheat, and re-solution treat where properties matter.
Can ZL203 be formed, bent or molded?
Sand and permanent-mould casting only; long freezing range demands generous risers, chills and directional solidification to avoid hot tears and shrinkage porosity — not suitable for pressure-tight castings.
What surface finishes work on ZL203?
Anodizing gives grey, non-decorative films because of the copper; prefer chromate/phosphate conversion coating plus primer and paint, or hard anodize where wear resistance dominates.
ZL203 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 |
|---|---|---|
| Cuprincipal strengthening element | 4 – 5 | 4.5 |
| Siimpurity limit (sand cast); improves fluidity | ≤ 1.2 | 0.6 |
| Feimpurity; 1.0 max for permanent-mould in some sources | ≤ 0.8 | — |
| Mgimpurity | ≤ 0.05 | — |
| Mnimpurity | ≤ 0.1 | — |
| Znimpurity | ≤ 0.25 | — |
| Niimpurity | ≤ 0.1 | — |
| Tigrain refiner residue / impurity | ≤ 0.2 | — |
| others (each)total impurities ≤ 2.1 % (sand) / ≤ 1.5 % (permanent mould) | ≤ 0.05 | — |
| Al | balance | — |
ZL203-T7 — frequently asked
What is ZL203-T7 used for?
ZL203-T7 is typically used for general machinery castings, gear housings and covers, machine tool brackets and bases, fixture and jig bodies, non-pressure instrument housings and heavily machined prototype castings. In short: best-machining cast aluminum; low-cost Al-Cu sand casting; not for pressure-tight parts.
What is the yield strength of ZL203-T7?
ZL203-T7 has a typical yield strength of 150 MPa (21.8 ksi) and a tensile strength of 200 MPa (29 ksi) — weaker than 65% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is ZL203-T7 easy to machine?
Yes — machinability is rated very good (80/100, better than 92% of aluminum grades). Excellent — one of the best-machining cast aluminium alloys; use polished-flute carbide or PCD, high speed, low feed, and flood coolant; T5/T6 gives cleaner surfaces than as-cast.
Can ZL203-T7 be welded?
Not readily — weldability is rated poor (25/100). Poor — Al-Cu is highly hot-crack sensitive; repair-weld only with 4043/2319 filler, low heat input and preheat, and re-solution treat where properties matter.
What surface finishes work on ZL203-T7?
Anodizing gives grey, non-decorative films because of the copper; prefer chromate/phosphate conversion coating plus primer and paint, or hard anodize where wear resistance dominates.
Can ZL203-T7 be formed, bent or molded?
Sand and permanent-mould casting only; long freezing range demands generous risers, chills and directional solidification to avoid hot tears and shrinkage porosity — not suitable for pressure-tight castings.
What is the maximum service temperature of ZL203-T7?
ZL203-T7 is rated for continuous use to about 175°C (347 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ZL203-T4 and ZL203-T6?
T4 is the default condition — standard supply condition: best combination of strength and ductility/toughness for general engineering castings. T6: peak-strength condition used mainly on the ANSI 295.0 equivalent when maximum hardness/wear resistance is required. Yield strength is 110 MPa in T4 versus 165 MPa in T6.
Sources
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (295.0, 208.0 data) — ASM International (1990)
- ASTM B26/B26M — Aluminum-Alloy Sand Castings — ASTM International (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.