Magnesium Alloy ML5-T4
Temper · default condition
T4 = solution heat treated and naturally aged
Standard aerospace condition for ML5 castings — best combination of strength, ductility and impact resistance.
Values for the T4 condition
Other ML5 tempers and conditions
ML5 is listed in 5 conditions; see the grade overview at ML5.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Cooled from hot working, cold worked and naturally aged | Use when residual stress from casting, welding or heavy machining must be removed and strength is secondary. | 85 | 160 | 3 | 52 HB | 13 % IACS |
T4DefaultThis page Solution heat treated and naturally aged | Standard aerospace condition for ML5 castings — best combination of strength, ductility and impact resistance. | 95 | 260 | 8 | 60 HB | 72 W/m·K |
As fabricated | Lowest cost condition for lightly loaded housings and covers where ductility is not critical. | 95 | 165 | 2.5 | 55 HB | 72 W/m·K |
Cooled from hot working and naturally aged | Simple ageing of the as-cast part to raise yield strength and stabilise dimensions without a solution treatment. | 110 | 195 | 2 | 65 HB | 12.5 % IACS |
Solution heat treated and artificially aged | Pick when maximum yield strength, hardness and dimensional stability matter more than ductility. | 135 | 275 | 4 | 70 HB | 72 W/m·K |
What is ML5-T4?
ML5-T4 is ML5 in the T4 temper — standard aerospace condition for ML5 castings — best combination of strength, ductility and impact resistance. ML5-T4 has a yield strength of 95 MPa (13.8 ksi) and a tensile strength of 260 MPa (37.7 ksi) — weaker than 93% of magnesium alloy grades. Elongation at break is 8% and the elastic modulus is 45 GPa (6.53 Msi). ML5-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
- Low strength — 95 MPa (13.8 ksi), worse than 93% of magnesium alloy grades
- Limited service temperature — 120°C (248 °F), worse than 78% of magnesium alloy grades
- Low electrical conductivity — 12 % IACS, worse than 78% of magnesium alloy grades
ML5-T4 properties
Typical room-temperature values for ML5-T4; 12 are specific to this condition. Other listed values are ML5 reference data and may not represent this condition. Bars are the position among magnesium alloy grades.
Physical3
ML5-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).
Mechanical13
ML5-T4 has a yield strength of 95 MPa (13.8 ksi) and a tensile strength of 260 MPa (37.7 ksi) — weaker than 93% of magnesium alloy grades. Elongation at break is 8% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
ML5-T4 is rated for continuous service to 120°C (248 °F). It conducts heat at 72 W/m·K (41.6 BTU/hr·ft·°F), worse than 69% of magnesium alloy grades. Thermal expansion is 26 µm/m·K (14.4 µin/in·°F).
Electrical3
ML5-T4 conducts electricity at 12 % IACS, worse than 78% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), worse than 77% of magnesium alloy grades.
Sustainability4
Producing a kilogram of ML5-T4 takes about 320 MJ of energy and emits 30 kg of CO₂ — less than 74% of magnesium alloy grades. Typical recycled content is 30%.
Manufacturability8
ML5-T4's machinability is excellent (98/100, better than 96% of magnesium alloy grades); weldability good (65/100); formability poor (15/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ML5-T4
Is ML5 easy to machine?
Outstanding machinability with sharp, high-rake tooling and high speeds; use dry or mineral-oil cutting (never water-based) and manage fine chips against fire risk.
Can ML5 be welded?
Readily GTAW/GMAW welded with AZ92A or AZ101 filler in argon; preheat thick sections and stress-relieve or re-solution treat after welding.
Can ML5 be formed, bent or molded?
Sand and permanent-mould casting alloy with good fluidity and low hot-tearing tendency; melt must be flux- or SF6/SO2-protected and grain refined by superheat.
What surface finishes work on ML5?
No conventional anodizing — use chromate/Dow 17/HAE conversion coatings or plasma-electrolytic oxidation, then epoxy primer and paint; isolate from steel and aluminium fasteners to avoid galvanic attack.
ML5 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 |
|---|---|---|
| Alprimary strengthening element (Mg17Al12) | 7.5 – 9 | 8.3 |
| Zn | 0.2 – 0.8 | 0.5 |
| Mncontrols Fe for corrosion resistance | 0.15 – 0.5 | 0.3 |
| Siimpurity | ≤ 0.25 | — |
| Cuimpurity | ≤ 0.1 | — |
| Feimpurity | ≤ 0.06 | — |
| Niimpurity, strongly harmful to corrosion | ≤ 0.01 | — |
| Bemelt oxidation inhibitor | ≤ 0 | — |
| Mg | balance | — |
ML5-T4 — frequently asked
What is ML5-T4 used for?
ML5-T4 is typically used for gearbox housings, aircraft fitting castings and machinery housings. In short: best-machining cast magnesium; weldable AZ91C-type casting; heat-treatable to T6.
What is the yield strength of ML5-T4?
ML5-T4 has a typical yield strength of 95 MPa (13.8 ksi) and a tensile strength of 260 MPa (37.7 ksi) — weaker than 93% of magnesium alloy grades. Strength varies by condition: see the 5 listed tempers.
Is ML5-T4 easy to machine?
Yes — machinability is rated excellent (98/100, better than 96% of magnesium alloy grades). Outstanding machinability with sharp, high-rake tooling and high speeds; use dry or mineral-oil cutting (never water-based) and manage fine chips against fire risk.
Can ML5-T4 be welded?
Yes — weldability is rated good (65/100). Readily GTAW/GMAW welded with AZ92A or AZ101 filler in argon; preheat thick sections and stress-relieve or re-solution treat after welding.
What surface finishes work on ML5-T4?
No conventional anodizing — use chromate/Dow 17/HAE conversion coatings or plasma-electrolytic oxidation, then epoxy primer and paint; isolate from steel and aluminium fasteners to avoid galvanic attack.
Can ML5-T4 be formed, bent or molded?
Sand and permanent-mould casting alloy with good fluidity and low hot-tearing tendency; melt must be flux- or SF6/SO2-protected and grain refined by superheat.
What is the maximum service temperature of ML5-T4?
ML5-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 ML5-T4 and ML5-T6?
T4 is the default condition — standard aerospace condition for ML5 castings — best combination of strength, ductility and impact resistance. T6: pick when maximum yield strength, hardness and dimensional stability matter more than ductility. Yield strength is 95 MPa in T4 versus 135 MPa in T6.
Sources
- GOST 2856-79 Magnesium casting alloys — grades — Gosstandart (1979)
- ASTM B80 / ASTM B403 Magnesium-Alloy Sand and Investment Castings (AZ91C/AZ91E) — ASTM International (2020)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Specialty Handbook: Magnesium and Magnesium Alloys — ASM International (1999)
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.