Magnesium Alloy ZK61A
ASTM ZK61A · UNS M16610
ZK61A is the cast counterpart of wrought ZK60A: a Mg-Zn-Zr sand and permanent-mould casting alloy (UNS M16610) with no rare-earth additions, used mainly in T5 and T6.
Reference datasheet — ZK61A 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 T6 condition
ZK61A tempers and conditions
ZK61A is supplied in 2 conditions, soft to hard. T6 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 |
|---|---|---|---|---|---|---|
Cooled from hot working and artificially aged | Pick when strength close to T6 is needed with minimal distortion risk and no solution-treatment furnace cycle. | 185 | 310 | 8 | 65 HB | 25 % IACS |
T6Default Solution heat treated and artificially aged | Standard aerospace condition: highest combination of yield strength and ductility for ZK61A castings. | 195 | 310 | 10 | 70 HB | 25 % IACS |
What is ZK61A?
ZK61A is the cast counterpart of wrought ZK60A: a Mg-Zn-Zr sand and permanent-mould casting alloy (UNS M16610) with no rare-earth additions, used mainly in T5 and T6. In T6 it reaches 195 MPa yield, 310 MPa tensile, 10% elongation and 70 HB at 45 GPa modulus, with 122 W/m·K conductivity, 25% IACS and a machinability score of 97, making it the strength leader of the ZK casting series. Limits are the 120 °C service temperature, low corrosion resistance (score 22), marginal weldability (score 30) and hot-tear/porosity sensitivity in the foundry. ZK51A is the lower-strength, easier-to-pour option. ZK61A has a density of 1.83 g/cm³ (0.0661 lb/in³), heavier than 81% of magnesium alloy grades. It melts at 520°C (968 °F). ZK61A has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 310 MPa (45 ksi) — stronger than 82% of magnesium alloy grades. Elongation at break is 10% and the elastic modulus is 45 GPa (6.53 Msi).
What is ZK61A used for?
- High-strength aerospace sand castings
- Airframe and engine accessory brackets
- Structural housings for avionics
- Permanent-mould load-bearing castings
- Missile and UAV structural components
- Weight-critical gearbox covers
Advantages
- Low embodied carbon — 26 kg CO₂/kg, better than 96% of magnesium alloy grades
- Conducts heat well — 122 W/m·K (70.5 BTU/hr·ft·°F), better than 88% of magnesium alloy grades
- High strength — 195 MPa (28.3 ksi), better than 82% of magnesium alloy grades
Limitations
- Hard to polish — 45/100, worse than 93% of magnesium alloy grades
- Difficult to weld — 30/100, worse than 90% of magnesium alloy grades
- Limited service temperature — 120°C (248 °F), worse than 78% of magnesium alloy grades
ZK61A properties
Typical room-temperature values for ZK61A-T6; bars are the position among magnesium alloy grades.
Physical3
ZK61A has a density of 1.83 g/cm³ (0.0661 lb/in³), heavier than 81% of magnesium alloy grades. It melts at 520°C (968 °F).
Mechanical14
ZK61A has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 310 MPa (45 ksi) — stronger than 82% of magnesium alloy grades. Elongation at break is 10% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
ZK61A is rated for continuous service to 120°C (248 °F). It conducts heat at 122 W/m·K (70.5 BTU/hr·ft·°F), better than 88% of magnesium alloy grades. Thermal expansion is 27 µm/m·K (15 µin/in·°F).
Electrical3
ZK61A conducts electricity at 25 % IACS, better than 69% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (22/100), worse than 57% of magnesium alloy grades.
Sustainability4
Producing a kilogram of ZK61A takes about 300 MJ of energy and emits 26 kg of CO₂ — less than 92% of magnesium alloy grades. Typical recycled content is 20%.
Manufacturability8
ZK61A's machinability is excellent (97/100, better than 92% of magnesium alloy grades); weldability poor (30/100); formability poor (15/100).
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. ZK61A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ZK61A
Is ZK61A easy to machine?
Cuts extremely freely with sharp positive-rake tools, high speed and low force; run dry or with mineral oil (never water-based) and manage fine chips/dust for fire risk.
Can ZK61A be welded?
GTAW with ZK61A/EZ33-type filler is possible but the alloy is hot-crack and porosity sensitive; preheat, minimize restraint, and re-solution/re-age critical repairs.
Can ZK61A be formed, bent or molded?
Sand and permanent-mold casting only — Zr grain refinement, protective SF6-free cover gas, generous risering and controlled solidification are needed to avoid hot tearing and microporosity; HIP or impregnation is sometimes used for pressure tightness.
ZK61A 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 |
|---|---|---|
| Znprimary strengthening addition | 5.5 – 6.5 | 6 |
| Zrgrain refiner (soluble Zr basis) | 0.6 – 1 | 0.7 |
| Cuimpurity limit | ≤ 0.1 | |
| Niimpurity limit (corrosion) | ≤ 0.01 | |
| Siimpurity limit | ≤ 0.05 | |
| Others (each)0.30 % total | ≤ 0.1 | |
| Mg | balance |
What surface finishes work on ZK61A?
Not sulfuric-anodizable: apply chromate/fluoride conversion (MIL-M-3171) or PEO/HAE, then epoxy primer and topcoat; isolate from steel and aluminium fasteners to prevent galvanic attack.
Equivalent designations
Standards and trade names that resolve to Magnesium Alloy ZK61A in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- M16610
How much does ZK61A cost?
ZK61A is a premium-cost magnesium alloy ($$$), cheaper than about 51% 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.
ZK61A — frequently asked
What is ZK61A used for?
ZK61A is typically used for high-strength aerospace sand castings, airframe and engine accessory brackets, structural housings for avionics, permanent-mould load-bearing castings, missile and UAV structural components and weight-critical gearbox covers. In short: strongest ZK casting grade; rare-earth-free high-strength Mg; poor corrosion resistance.
What is the yield strength of ZK61A?
ZK61A has a typical yield strength of 195 MPa (28.3 ksi) and a tensile strength of 310 MPa (45 ksi) — stronger than 82% of magnesium alloy grades. Strength varies by condition: see the 2 listed tempers.
Is ZK61A easy to machine?
Yes — machinability is rated excellent (97/100, better than 92% of magnesium alloy grades). Cuts extremely freely with sharp positive-rake tools, high speed and low force; run dry or with mineral oil (never water-based) and manage fine chips/dust for fire risk.
Can ZK61A be welded?
Not readily — weldability is rated poor (30/100). GTAW with ZK61A/EZ33-type filler is possible but the alloy is hot-crack and porosity sensitive; preheat, minimize restraint, and re-solution/re-age critical repairs.
What surface finishes work on ZK61A?
Not sulfuric-anodizable: apply chromate/fluoride conversion (MIL-M-3171) or PEO/HAE, then epoxy primer and topcoat; isolate from steel and aluminium fasteners to prevent galvanic attack.
Can ZK61A be formed, bent or molded?
Sand and permanent-mold casting only — Zr grain refinement, protective SF6-free cover gas, generous risering and controlled solidification are needed to avoid hot tearing and microporosity; HIP or impregnation is sometimes used for pressure tightness.
What is the maximum service temperature of ZK61A?
ZK61A 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 ZK61A-T6 and ZK61A-T5?
T6 is the default condition — standard aerospace condition: highest combination of yield strength and ductility for ZK61A castings. T5: pick when strength close to T6 is needed with minimal distortion risk and no solution-treatment furnace cycle. Yield strength is 195 MPa in T6 versus 185 MPa in T5.
How much does ZK61A cost?
ZK61A is a premium-cost magnesium alloy ($$$), cheaper than about 51% 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
- ASTM B80 — Magnesium-Alloy Sand Castings — ASTM International (2015)
- ASTM B199 — Magnesium-Alloy Permanent Mold Castings — ASTM International (2019)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Specialty Handbook: Magnesium and Magnesium Alloys — ASM International (1999)
- MIL-M-3171 — Magnesium Alloy, Processes for Pretreatment and Prevention of Corrosion — US DoD (1996)
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.