Magnesium Alloy ZM4-T6
Temper
T6 = solution heat treated and artificially aged
Used only on thin-wall, chill/investment castings processed by the ZE63A hydrogen heat-treatment route when maximum tensile properties are required.
Values for the T6 condition
Other ZM4 tempers and conditions
ZM4 is listed in 3 conditions; see the grade overview at ZM4.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Pick for lightly loaded, pressure-tight housings where the aging cycle is not economically justified. | 85 | 135 | 3 | 48 HB | 23 % IACS |
T1Default Cooled from hot working and naturally aged | Standard supplied condition for ZM4 castings per GB/T 1177 — best balance of strength, ductility and dimensional stability. | 100 | 160 | 3 | 55 HB | 25 % IACS |
T6This page Solution heat treated and artificially aged | Used only on thin-wall, chill/investment castings processed by the ZE63A hydrogen heat-treatment route when maximum tensile properties are required. | 180 | 280 | 8 | 65 HB | 27 % IACS |
What is ZM4-T6?
ZM4-T6 is ZM4 in the T6 temper — used only on thin-wall, chill/investment castings processed by the ZE63A hydrogen heat-treatment route when maximum tensile properties are required. ZM4-T6 has a yield strength of 180 MPa (26.1 ksi) and a tensile strength of 280 MPa (40.6 ksi) — stronger than 75% of magnesium alloy grades. Elongation at break is 8% and the elastic modulus is 44 GPa (6.38 Msi). ZM4-T6 has a density of 1.83 g/cm³ (0.0661 lb/in³), heavier than 81% of magnesium alloy grades. It melts at 510°C (950 °F). T1 is the default condition FabDigit quotes; T6 is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 17 MPa·√m (15.5 ksi·√in), better than 94% of magnesium alloy grades
- Conducts heat well — 120 W/m·K (69.3 BTU/hr·ft·°F), better than 83% of magnesium alloy grades
- High electrical conductivity — 27 % IACS, better than 80% of magnesium alloy grades
- High strength — 180 MPa (26.1 ksi), better than 75% of magnesium alloy grades
ZM4-T6 properties
Typical room-temperature values for ZM4-T6; 21 are specific to this condition. Other listed values are ZM4 reference data and may not represent this condition. Bars are the position among magnesium alloy grades.
Physical3
ZM4-T6 has a density of 1.83 g/cm³ (0.0661 lb/in³), heavier than 81% of magnesium alloy grades. It melts at 510°C (950 °F).
Mechanical15
ZM4-T6 has a yield strength of 180 MPa (26.1 ksi) and a tensile strength of 280 MPa (40.6 ksi) — stronger than 75% of magnesium alloy grades. Elongation at break is 8% and the elastic modulus is 44 GPa (6.38 Msi).
Thermal6
ZM4-T6 is rated for continuous service to 150°C (302 °F). It conducts heat at 120 W/m·K (69.3 BTU/hr·ft·°F), better than 83% of magnesium alloy grades. Thermal expansion is 26.5 µm/m·K (14.7 µin/in·°F).
Electrical3
ZM4-T6 conducts electricity at 27 % IACS, better than 80% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (24/100), better than 55% of magnesium alloy grades.
Sustainability4
Producing a kilogram of ZM4-T6 takes about 320 MJ of energy and emits 30 kg of CO₂ — less than 74% of magnesium alloy grades. Typical recycled content is 15%.
Manufacturability8
ZM4-T6's machinability is excellent (92/100, worse than 86% of magnesium alloy grades); weldability fair (50/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ZM4-T6
Is ZM4 easy to machine?
Machines extremely easily at high speeds with sharp, positive-rake tools; use flood coolant or dry with chip control and never let fine chips/dust accumulate — Mg fines are a fire hazard (Class D extinguisher on hand).
Can ZM4 be welded?
TIG/GTAW in argon with EZ33A or matching Mg-RE-Zn filler works for foundry repair; preheat 150–260 °C and stress-relieve after welding to limit hot cracking around the Zn-rich grain boundaries.
Can ZM4 be formed, bent or molded?
Foundry alloy only — sand, investment and permanent-mould casting with SF6-free protective cover gas or flux; Zr grain refinement gives fine, pressure-tight structure but requires clean, low-Fe melt practice.
What surface finishes work on ZM4?
Always apply a chromate-free conversion coating or MAO/HAE anodic film followed by epoxy primer and topcoat; insulate from steel/aluminium fasteners to avoid severe galvanic attack.
ZM4 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 |
|---|---|---|
| Zn | 2 – 3 | 2.5 |
| RE (Ce-rich mischmetal)Ce-rich mischmetal, ≥45 % Ce | 2.5 – 4 | 3 |
| Zrgrain refiner, soluble Zr | 0.5 – 1 | 0.7 |
| Alimpurity limit | ≤ 0.02 | — |
| Siimpurity limit | ≤ 0.01 | — |
| Feimpurity limit | ≤ 0.01 | — |
| Cuimpurity limit | ≤ 0.03 | — |
| Niimpurity limit | ≤ 0.01 | — |
| Others (total)total impurities | ≤ 0.3 | — |
| Mg | balance | — |
ZM4-T6 — frequently asked
What is ZM4-T6 used for?
ZM4-T6 is typically used for aerospace structural castings, high-strength gearbox housings, aircraft accessory housings, pressure-tight cast covers, cast brackets and mounts and missile structural castings. In short: highest-strength RE casting; fine Zr-refined structure; pressure-tight castings.
What is the yield strength of ZM4-T6?
ZM4-T6 has a typical yield strength of 180 MPa (26.1 ksi) and a tensile strength of 280 MPa (40.6 ksi) — stronger than 75% of magnesium alloy grades. Strength varies by condition: see the 3 listed tempers.
Is ZM4-T6 easy to machine?
Yes — machinability is rated excellent (92/100, worse than 86% of magnesium alloy grades). Machines extremely easily at high speeds with sharp, positive-rake tools; use flood coolant or dry with chip control and never let fine chips/dust accumulate — Mg fines are a fire hazard (Class D extinguisher on hand).
Can ZM4-T6 be welded?
With care — weldability is rated fair (50/100). TIG/GTAW in argon with EZ33A or matching Mg-RE-Zn filler works for foundry repair; preheat 150–260 °C and stress-relieve after welding to limit hot cracking around the Zn-rich grain boundaries.
What surface finishes work on ZM4-T6?
Always apply a chromate-free conversion coating or MAO/HAE anodic film followed by epoxy primer and topcoat; insulate from steel/aluminium fasteners to avoid severe galvanic attack.
Can ZM4-T6 be formed, bent or molded?
Foundry alloy only — sand, investment and permanent-mould casting with SF6-free protective cover gas or flux; Zr grain refinement gives fine, pressure-tight structure but requires clean, low-Fe melt practice.
What is the maximum service temperature of ZM4-T6?
ZM4-T6 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ZM4-T1 and ZM4-T6?
T1 is the default condition — standard supplied condition for ZM4 castings per GB/T 1177 — best balance of strength, ductility and dimensional stability. T6: used only on thin-wall, chill/investment castings processed by the ZE63A hydrogen heat-treatment route when maximum tensile properties are required. Yield strength is 100 MPa in T1 versus 180 MPa in T6.
Sources
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (Magnesium Casting Alloys) — ASM International (1990)
- ASTM B80 — Magnesium-Alloy Sand Castings (ZE41A/ZE63A) — ASTM International (2020)
- ASM Handbook Vol. 13B — Corrosion: Materials (Magnesium) — ASM International (2005)
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.