Magnesium Alloy ZK61A-T6
Temper · default condition
ASTM ZK61A · UNS M16610
T6 = solution heat treated and artificially aged
Standard aerospace condition: highest combination of yield strength and ductility for ZK61A castings.
Values for the T6 condition
Other ZK61A tempers and conditions
ZK61A is listed in 2 conditions; see the grade overview at ZK61A.
- T5
- T6
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 |
T6DefaultThis page 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-T6?
ZK61A-T6 is ZK61A in the T6 temper — standard aerospace condition: highest combination of yield strength and ductility for ZK61A castings. ZK61A-T6 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). ZK61A-T6 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).
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-T6 properties
Typical room-temperature values for ZK61A-T6; 21 are specific to this condition. Other listed values are ZK61A reference data and may not represent this condition. Bars are the position among magnesium alloy grades.
Physical3
ZK61A-T6 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-T6 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-T6 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-T6 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-T6 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-T6'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. Confirm any required mill or lot documentation when quoting.
Working with ZK61A-T6
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.
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.
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 | — |
ZK61A-T6 — frequently asked
What is ZK61A-T6 used for?
ZK61A-T6 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-T6?
ZK61A-T6 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-T6 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-T6 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-T6?
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-T6 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-T6?
ZK61A-T6 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.