Magnesium Alloy MC3
JIS MC3
MC3 is a JIS Mg-Zn-Zr sand and permanent-mould casting alloy equivalent to ZK51A, strengthened by zinc with zirconium grain refinement instead of aluminium.
Reference datasheet — MC3 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the T5 condition
MC3 tempers and conditions
MC3 is supplied in 2 conditions, soft to hard. T5 is the default FabDigit quotes; the values on this page are for it.
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 |
T5Default 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?
MC3 is a JIS Mg-Zn-Zr sand and permanent-mould casting alloy equivalent to ZK51A, strengthened by zinc with zirconium grain refinement instead of aluminium. Engineers specify it for higher-strength castings: 165 MPa yield, 275 MPa tensile, 65 HB, 109 W/m·K thermal conductivity and machinability rated 95, supplied in F and T5. The limits are low ductility at 3.5% elongation, a 150 °C service ceiling, poor weldability (score 30) from hot-crack sensitivity, and mandatory corrosion protection; ML5/AZ91C is the cheaper and more weldable alternative. MC3 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). MC3 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).
What is MC3 used for?
- High-strength magnesium sand castings
- Aerospace-adjacent structural castings
- Gearbox and transmission housings
- Weight-critical machinery brackets
- Permanent-mould instrument housings
- Avionics and equipment enclosures
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 properties
Typical room-temperature values for MC3-T5; bars are the position among magnesium alloy grades.
Physical3
MC3 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 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 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 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 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'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. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the magnesium alloy family
Yield strength against density for every magnesium alloy grade FabDigit runs. MC3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with MC3
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.
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 |
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.
Equivalent designations
Standards and trade names that resolve to Magnesium Alloy MC3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- ZK51A
How much does MC3 cost?
MC3 is a high-cost magnesium alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
MC3 — frequently asked
What is MC3 used for?
MC3 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?
MC3 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 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 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?
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 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?
MC3 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.
How much does MC3 cost?
MC3 is a high-cost magnesium alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.