Magnesium Alloy ZM4
ZM4 is a Mg-RE-Zn-Zr casting alloy analogous to ZE63A, developed for the highest tensile properties available from the rare-earth cast magnesium group.
Reference datasheet — ZM4 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 T1 condition
ZM4 tempers and conditions
ZM4 is supplied in 3 conditions, soft to hard. T1 is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Pick for lightly loaded, pressure-tight housings where the aging cycle is not economically justified. | 85 | 135 | 3 | 48 HB | 23 % IACS |
T1Default Cooled from hot working and naturally aged | Standard supplied condition for ZM4 castings per GB/T 1177 — best balance of strength, ductility and dimensional stability. | 100 | 160 | 3 | 55 HB | 25 % IACS |
Solution heat treated and artificially aged | Used only on thin-wall, chill/investment castings processed by the ZE63A hydrogen heat-treatment route when maximum tensile properties are required. | 180 | 280 | 8 | 65 HB | 27 % IACS |
What is ZM4?
ZM4 is a Mg-RE-Zn-Zr casting alloy analogous to ZE63A, developed for the highest tensile properties available from the rare-earth cast magnesium group. Supplied as castings in F, T1 and T6 conditions, it reaches 100 MPa yield, 160 MPa tensile, 3% elongation and 55 HB, with zirconium grain refinement giving a fine, pressure-tight structure. Maximum service temperature is 175 °C, the alloy is not formable and always needs a protective coating system; ZM3 (EZ33A) is the alternative when 250 °C creep resistance matters more than strength. ZM4 has a density of 1.83 g/cm³ (0.0661 lb/in³), heavier than 81% of magnesium alloy grades. It melts at 510°C (950 °F). ZM4 has a yield strength of 100 MPa (14.5 ksi) and a tensile strength of 160 MPa (23.2 ksi) — weaker than 88% of magnesium alloy grades. Elongation at break is 3% and the elastic modulus is 44 GPa (6.38 Msi).
What is ZM4 used for?
- Aerospace structural castings
- High-strength gearbox housings
- Aircraft accessory housings
- Pressure-tight cast covers
- Cast brackets and mounts
- Missile structural castings
Advantages
- High service temperature — 175°C (347 °F), better than 79% of magnesium alloy grades
Limitations
- Low strength — 100 MPa (14.5 ksi), worse than 88% of magnesium alloy grades
- Limited ductility — 3%, worse than 85% of magnesium alloy grades
ZM4 properties
Typical room-temperature values for ZM4-T1; bars are the position among magnesium alloy grades.
Physical3
ZM4 has a density of 1.83 g/cm³ (0.0661 lb/in³), heavier than 81% of magnesium alloy grades. It melts at 510°C (950 °F).
Mechanical15
ZM4 has a yield strength of 100 MPa (14.5 ksi) and a tensile strength of 160 MPa (23.2 ksi) — weaker than 88% of magnesium alloy grades. Elongation at break is 3% and the elastic modulus is 44 GPa (6.38 Msi).
Thermal6
ZM4 is rated for continuous service to 175°C (347 °F). It conducts heat at 110 W/m·K (63.6 BTU/hr·ft·°F), better than 66% of magnesium alloy grades. Thermal expansion is 26.5 µm/m·K (14.7 µin/in·°F).
Electrical3
ZM4 conducts electricity at 25 % IACS, better than 69% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), better than 64% of magnesium alloy grades.
Sustainability4
Producing a kilogram of ZM4 takes about 320 MJ of energy and emits 30 kg of CO₂ — less than 74% of magnesium alloy grades. Typical recycled content is 15%.
Manufacturability8
ZM4's machinability is excellent (92/100, worse than 86% of magnesium alloy grades); weldability good (60/100); 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. ZM4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ZM4
Is ZM4 easy to machine?
Machines extremely easily at high speeds with sharp, positive-rake tools; use flood coolant or dry with chip control and never let fine chips/dust accumulate — Mg fines are a fire hazard (Class D extinguisher on hand).
Can ZM4 be welded?
TIG/GTAW in argon with EZ33A or matching Mg-RE-Zn filler works for foundry repair; preheat 150–260 °C and stress-relieve after welding to limit hot cracking around the Zn-rich grain boundaries.
Can ZM4 be formed, bent or molded?
Foundry alloy only — sand, investment and permanent-mould casting with SF6-free protective cover gas or flux; Zr grain refinement gives fine, pressure-tight structure but requires clean, low-Fe melt practice.
ZM4 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 |
|---|---|---|
| Zn | 2 – 3 | 2.5 |
| RE (Ce-rich mischmetal)Ce-rich mischmetal, ≥45 % Ce | 2.5 – 4 | 3 |
| Zrgrain refiner, soluble Zr | 0.5 – 1 | 0.7 |
| Alimpurity limit | ≤ 0.02 | |
| Siimpurity limit | ≤ 0.01 | |
| Feimpurity limit | ≤ 0.01 | |
| Cuimpurity limit | ≤ 0.03 | |
| Niimpurity limit | ≤ 0.01 | |
| Others (total)total impurities | ≤ 0.3 | |
| Mg | balance |
What surface finishes work on ZM4?
Always apply a chromate-free conversion coating or MAO/HAE anodic film followed by epoxy primer and topcoat; insulate from steel/aluminium fasteners to avoid severe galvanic attack.
Equivalent designations
Standards and trade names that resolve to Magnesium Alloy ZM4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- ZE63A
How much does ZM4 cost?
ZM4 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.
ZM4 — frequently asked
What is ZM4 used for?
ZM4 is typically used for aerospace structural castings, high-strength gearbox housings, aircraft accessory housings, pressure-tight cast covers, cast brackets and mounts and missile structural castings. In short: highest-strength RE casting; fine Zr-refined structure; pressure-tight castings.
What is the yield strength of ZM4?
ZM4 has a typical yield strength of 100 MPa (14.5 ksi) and a tensile strength of 160 MPa (23.2 ksi) — weaker than 88% of magnesium alloy grades. Strength varies by condition: see the 3 listed tempers.
Is ZM4 easy to machine?
Yes — machinability is rated excellent (92/100, worse than 86% of magnesium alloy grades). Machines extremely easily at high speeds with sharp, positive-rake tools; use flood coolant or dry with chip control and never let fine chips/dust accumulate — Mg fines are a fire hazard (Class D extinguisher on hand).
Can ZM4 be welded?
Yes — weldability is rated good (60/100). TIG/GTAW in argon with EZ33A or matching Mg-RE-Zn filler works for foundry repair; preheat 150–260 °C and stress-relieve after welding to limit hot cracking around the Zn-rich grain boundaries.
What surface finishes work on ZM4?
Always apply a chromate-free conversion coating or MAO/HAE anodic film followed by epoxy primer and topcoat; insulate from steel/aluminium fasteners to avoid severe galvanic attack.
Can ZM4 be formed, bent or molded?
Foundry alloy only — sand, investment and permanent-mould casting with SF6-free protective cover gas or flux; Zr grain refinement gives fine, pressure-tight structure but requires clean, low-Fe melt practice.
What is the maximum service temperature of ZM4?
ZM4 is rated for continuous use to about 175°C (347 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ZM4-T1 and ZM4-T6?
T1 is the default condition — standard supplied condition for ZM4 castings per GB/T 1177 — best balance of strength, ductility and dimensional stability. T6: used only on thin-wall, chill/investment castings processed by the ZE63A hydrogen heat-treatment route when maximum tensile properties are required. Yield strength is 100 MPa in T1 versus 180 MPa in T6.
How much does ZM4 cost?
ZM4 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
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (Magnesium Casting Alloys) — ASM International (1990)
- ASTM B80 — Magnesium-Alloy Sand Castings (ZE41A/ZE63A) — ASTM International (2020)
- ASM Handbook Vol. 13B — Corrosion: Materials (Magnesium) — ASM International (2005)
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.