Magnesium Alloy ZM5-T4
Temper · default condition
T4 = solution heat treated and naturally aged
Most-used ZM5 condition: best combination of strength, ductility and impact resistance for structural castings.
Values for the T4 condition
Other ZM5 tempers and conditions
ZM5 is listed in 6 conditions; see the grade overview at ZM5.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Cooled from hot working, cold worked and naturally aged | Low-temperature anneal used to relieve casting or machining stresses and stabilise dimensions before finish machining. | 85 | 160 | 3 | 52 HB | 13 % IACS |
T4DefaultThis page Solution heat treated and naturally aged | Most-used ZM5 condition: best combination of strength, ductility and impact resistance for structural castings. | 90 | 250 | 8 | 55 HB | 11.5 % IACS |
As fabricated | Lowest-cost condition for lightly loaded housings and covers where dimensional stability matters more than strength. | 90 | 165 | 2.5 | 55 HB | 12 % IACS |
Cooled from hot working and naturally aged | Simple ageing (≈175 °C) of the as-cast part to raise yield strength and hardness without a solution treatment or distortion risk. | 110 | 180 | 2 | 62 HB | 13 % IACS |
Solution heat treated and artificially aged | Choose when maximum yield strength and hardness are needed and low elongation is acceptable. | 140 | 255 | 4 | 70 HB | 13.5 % IACS |
Die cast, as-cast | High-pressure die-cast ZM5/AZ91D: fine chill structure gives higher strength than sand casting, but heat treatment is limited by gas porosity. | 150 | 230 | 3 | 63 HB | 12 % IACS |
What is ZM5-T4?
ZM5-T4 is ZM5 in the T4 temper — most-used ZM5 condition: best combination of strength, ductility and impact resistance for structural castings. ZM5-T4 has a yield strength of 90 MPa (13.1 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 96% of magnesium alloy grades. Elongation at break is 8% and the elastic modulus is 45 GPa (6.53 Msi). ZM5-T4 has a density of 1.81 g/cm³ (0.0654 lb/in³), heavier than 58% of magnesium alloy grades. It melts at 470°C (878 °F).
Limitations
- Poor heat conductor — 51 W/m·K (29.5 BTU/hr·ft·°F), worse than 97% of magnesium alloy grades
- Low strength — 90 MPa (13.1 ksi), worse than 96% of magnesium alloy grades
- Low electrical conductivity — 11.5 % IACS, worse than 92% of magnesium alloy grades
- Limited service temperature — 120°C (248 °F), worse than 78% of magnesium alloy grades
ZM5-T4 properties
Typical room-temperature values for ZM5-T4; 21 are specific to this condition. Other listed values are ZM5 reference data and may not represent this condition. Bars are the position among magnesium alloy grades.
Physical3
ZM5-T4 has a density of 1.81 g/cm³ (0.0654 lb/in³), heavier than 58% of magnesium alloy grades. It melts at 470°C (878 °F).
Mechanical15
ZM5-T4 has a yield strength of 90 MPa (13.1 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 96% of magnesium alloy grades. Elongation at break is 8% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
ZM5-T4 is rated for continuous service to 120°C (248 °F). It conducts heat at 51 W/m·K (29.5 BTU/hr·ft·°F), worse than 97% of magnesium alloy grades. Thermal expansion is 26 µm/m·K (14.4 µin/in·°F).
Electrical3
ZM5-T4 conducts electricity at 11.5 % IACS, worse than 92% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (24/100), better than 55% of magnesium alloy grades.
Sustainability4
Producing a kilogram of ZM5-T4 takes about 330 MJ of energy and emits 30 kg of CO₂ — less than 56% of magnesium alloy grades. Typical recycled content is 30%.
Manufacturability8
ZM5-T4's machinability is excellent (95/100, better than 54% of magnesium alloy grades); weldability good (60/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ZM5-T4
Is ZM5 easy to machine?
Cuts extremely easily with sharp positive-rake tools and high speeds; use dry or mineral-oil cutting (no water-based coolant) and control fine chips — magnesium swarf is a fire hazard.
Can ZM5 be welded?
GTAW/GMAW with AZ92A or AZ101 filler under argon works well; preheat thick sections, avoid welding heavily die-cast (gas-porous) parts, and stress relieve after welding.
Can ZM5 be formed, bent or molded?
A casting alloy — excellent fluidity and low hot-tearing tendency in sand, permanent-mould and high-pressure die casting; melt must be protected with SF6-free cover gas or flux.
What surface finishes work on ZM5?
Always apply chromate/phosphate conversion, Dow 17/HAE anodize or micro-arc oxidation plus paint; avoid direct contact with steel, copper or graphite to prevent galvanic corrosion.
ZM5 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 |
|---|---|---|
| Alprincipal strengthening element (Mg17Al12) | 7.5 – 9 | 8.3 |
| Zn | 0.2 – 0.8 | 0.5 |
| Mnties up Fe, improves corrosion behaviour | 0.15 – 0.5 | 0.3 |
| Siimpurity limit | ≤ 0.3 | — |
| Cuimpurity limit; AZ91D high-purity variants ≤0.030 | ≤ 0.1 | — |
| FeAZ91D high-purity variants ≤0.005 | ≤ 0.05 | — |
| NiAZ91D high-purity variants ≤0.002 | ≤ 0.01 | — |
| Beoptional melt-protection addition | 1×10⁻⁴ – 0 | 8×10⁻⁴ |
| Others (total) | ≤ 0.5 | — |
| Mg | balance | — |
ZM5-T4 — frequently asked
What is ZM5-T4 used for?
ZM5-T4 is typically used for gearbox housings, engine covers, electronic enclosures and automotive brackets. In short: general-purpose AZ91 equivalent; best-casting magnesium alloy; weldable with AZ92A filler.
What is the yield strength of ZM5-T4?
ZM5-T4 has a typical yield strength of 90 MPa (13.1 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 96% of magnesium alloy grades. Strength varies by condition: see the 6 listed tempers.
Is ZM5-T4 easy to machine?
Yes — machinability is rated excellent (95/100, better than 54% of magnesium alloy grades). Cuts extremely easily with sharp positive-rake tools and high speeds; use dry or mineral-oil cutting (no water-based coolant) and control fine chips — magnesium swarf is a fire hazard.
Can ZM5-T4 be welded?
Yes — weldability is rated good (60/100). GTAW/GMAW with AZ92A or AZ101 filler under argon works well; preheat thick sections, avoid welding heavily die-cast (gas-porous) parts, and stress relieve after welding.
What surface finishes work on ZM5-T4?
Always apply chromate/phosphate conversion, Dow 17/HAE anodize or micro-arc oxidation plus paint; avoid direct contact with steel, copper or graphite to prevent galvanic corrosion.
Can ZM5-T4 be formed, bent or molded?
A casting alloy — excellent fluidity and low hot-tearing tendency in sand, permanent-mould and high-pressure die casting; melt must be protected with SF6-free cover gas or flux.
What is the maximum service temperature of ZM5-T4?
ZM5-T4 is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ZM5-T4 and ZM5 DC-F?
T4 is the default condition — most-used ZM5 condition: best combination of strength, ductility and impact resistance for structural castings. DC-F: high-pressure die-cast ZM5/AZ91D: fine chill structure gives higher strength than sand casting, but heat treatment is limited by gas porosity. Yield strength is 90 MPa in T4 versus 150 MPa in DC-F.
Sources
- GB/T 1177 (ZM5 / ZMgAl8Zn) — SAC / (2018)
- ASTM B80 / B94 (AZ91C, AZ91D magnesium castings) — ASTM International (2021)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Specialty Handbook: Magnesium and Magnesium Alloys — ASM International (1999)
- ASM Handbook Vol.13B — Corrosion of Magnesium Alloys — 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.