Magnesium Alloy MC3-T5
Temper · default condition
JIS MC3
T5 = cooled from hot working and artificially aged
Standard supply condition for Mg-Zn-Zr sand castings — best strength/ductility balance without a solution treatment.
Values for the T5 condition
Other MC3 tempers and conditions
MC3 is listed in 2 conditions; see the grade overview at MC3.
- F
- T5
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Pick for lightly loaded castings or when the part will be aged later; lowest cost, slightly lower strength than T5. | 135 | 210 | 5 | 55 HB | 27 % IACS |
T5DefaultThis page Cooled from hot working and artificially aged | Standard supply condition for Mg-Zn-Zr sand castings — best strength/ductility balance without a solution treatment. | 165 | 275 | 3.5 | 65 HB | 109 W/m·K |
What is MC3-T5?
MC3-T5 is MC3 in the T5 temper — standard supply condition for Mg-Zn-Zr sand castings — best strength/ductility balance without a solution treatment. MC3-T5 has a yield strength of 165 MPa (23.9 ksi) and a tensile strength of 275 MPa (39.9 ksi) — stronger than 67% of magnesium alloy grades. Elongation at break is 3.5% and the elastic modulus is 45 GPa (6.53 Msi). MC3-T5 has a density of 1.81 g/cm³ (0.0654 lb/in³), heavier than 58% of magnesium alloy grades. It melts at 549°C (1,020 °F).
Advantages
- High electrical conductivity — 28 % IACS, better than 85% of magnesium alloy grades
Limitations
- Low fracture toughness — 12 MPa·√m (10.9 ksi·√in), worse than 92% of magnesium alloy grades
- Difficult to weld — 30/100, worse than 90% of magnesium alloy grades
MC3-T5 properties
Typical room-temperature values for MC3-T5; 13 are specific to this condition. Other listed values are MC3 reference data and may not represent this condition. Bars are the position among magnesium alloy grades.
Physical3
MC3-T5 has a density of 1.81 g/cm³ (0.0654 lb/in³), heavier than 58% of magnesium alloy grades. It melts at 549°C (1,020 °F).
Mechanical13
MC3-T5 has a yield strength of 165 MPa (23.9 ksi) and a tensile strength of 275 MPa (39.9 ksi) — stronger than 67% of magnesium alloy grades. Elongation at break is 3.5% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
MC3-T5 is rated for continuous service to 150°C (302 °F). It conducts heat at 109 W/m·K (63 BTU/hr·ft·°F), better than 63% of magnesium alloy grades. Thermal expansion is 27 µm/m·K (15 µin/in·°F).
Electrical3
MC3-T5 conducts electricity at 28 % IACS, better than 85% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), worse than 77% of magnesium alloy grades.
Sustainability4
Producing a kilogram of MC3-T5 takes about 350 MJ of energy and emits 32 kg of CO₂ — more than 74% of magnesium alloy grades. Typical recycled content is 25%.
Manufacturability7
MC3-T5's machinability is excellent (95/100, better than 54% of magnesium alloy grades); weldability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with MC3-T5
Is MC3 easy to machine?
Machines extremely fast with sharp, high-rake tooling and generous chip clearance; use dry or mineral-oil cutting, never water-based coolant, and control fine chips/dust for fire risk.
Can MC3 be welded?
GTAW with Mg-Zn-Zr filler is possible but hot-crack sensitive — repair welds should be small, preheated, and re-aged; avoid welding on highly stressed sections.
Can MC3 be formed, bent or molded?
Sand and permanent-mould cast only; needs SF6-free protective cover gas or flux, careful gating and chills to control the microporosity typical of Mg-Zn-Zr, and Zr must not be poisoned by Al/Si/Fe in the melt.
What surface finishes work on MC3?
Chromate-free conversion coating or Dow 17/HAE anodic film followed by epoxy primer and topcoat; isolate all steel/aluminium fasteners with sealant or coated washers to prevent galvanic attack.
MC3 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 |
|---|---|---|
| Znprincipal strengthening addition | 3.6 – 5.5 | 4.6 |
| Zrgrain refiner; must stay in solution | 0.5 – 1 | 0.7 |
| Cuimpurity limit | ≤ 0.1 | — |
| Niimpurity limit, corrosion critical | ≤ 0.01 | — |
| Feimpurity limit, corrosion critical | ≤ 0.05 | — |
| Alkept low; Al poisons Zr grain refinement | ≤ 0.05 | — |
| Siimpurity limit | ≤ 0.05 | — |
| Mnimpurity limit | ≤ 0.1 | — |
| Others (each)total others ≤ 0.30 | ≤ 0.05 | — |
| Mg | balance | — |
MC3-T5 — frequently asked
What is MC3-T5 used for?
MC3-T5 is typically used for high-strength magnesium sand castings, aerospace-adjacent structural castings, gearbox and transmission housings, weight-critical machinery brackets, permanent-mould instrument housings and avionics and equipment enclosures. In short: highest-strength cast magnesium; aluminium-free Mg-Zn-Zr casting; poor weldability, repair only.
What is the yield strength of MC3-T5?
MC3-T5 has a typical yield strength of 165 MPa (23.9 ksi) and a tensile strength of 275 MPa (39.9 ksi) — stronger than 67% of magnesium alloy grades. Strength varies by condition: see the 2 listed tempers.
Is MC3-T5 easy to machine?
Yes — machinability is rated excellent (95/100, better than 54% of magnesium alloy grades). Machines extremely fast with sharp, high-rake tooling and generous chip clearance; use dry or mineral-oil cutting, never water-based coolant, and control fine chips/dust for fire risk.
Can MC3-T5 be welded?
Not readily — weldability is rated poor (30/100). GTAW with Mg-Zn-Zr filler is possible but hot-crack sensitive — repair welds should be small, preheated, and re-aged; avoid welding on highly stressed sections.
What surface finishes work on MC3-T5?
Chromate-free conversion coating or Dow 17/HAE anodic film followed by epoxy primer and topcoat; isolate all steel/aluminium fasteners with sealant or coated washers to prevent galvanic attack.
Can MC3-T5 be formed, bent or molded?
Sand and permanent-mould cast only; needs SF6-free protective cover gas or flux, careful gating and chills to control the microporosity typical of Mg-Zn-Zr, and Zr must not be poisoned by Al/Si/Fe in the melt.
What is the maximum service temperature of MC3-T5?
MC3-T5 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 MC3-T5 and MC3-F?
T5 is the default condition — standard supply condition for Mg-Zn-Zr sand castings — best strength/ductility balance without a solution treatment. F: pick for lightly loaded castings or when the part will be aged later; lowest cost, slightly lower strength than T5. Yield strength is 165 MPa in T5 versus 135 MPa in F.
Sources
- JIS H 5203 — Magnesium alloy castings — Japanese Standards Association (2006)
- ASTM B80 — Magnesium-Alloy Sand Castings (ZK51A) — 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.