Magnesium Alloy ZM21
ASTM ZM21 · EN MgZn2Mn1 · ISO ISO-WD32350
ZM21 (MgZn2Mn1) is a zinc-manganese wrought magnesium alloy containing no zirconium or aluminium, supplied in O, H24 and F conditions.
Reference datasheet — ZM21 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 O condition
ZM21 tempers and conditions
ZM21 is supplied in 3 conditions, soft to hard. O 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 |
|---|---|---|---|---|---|---|
ODefault Annealed | Pick for maximum room-temperature and warm press formability — deep drawn, stretch-formed or bent panels. | 140 | 240 | 19 | 45 HB | 29 % IACS |
As fabricated | Default condition for extrusions and forgings where no post-work thermal treatment is applied. | 160 | 250 | 13 | 50 HB | 28 % IACS |
Strain hardened and partially annealed, half hard | Standard structural sheet temper: higher yield strength and stiffness-per-gauge with usable warm formability. | 195 | 265 | 9 | 58 HB | 27 % IACS |
What is ZM21?
ZM21 (MgZn2Mn1) is a zinc-manganese wrought magnesium alloy containing no zirconium or aluminium, supplied in O, H24 and F conditions. It is chosen for sheet stampings and extrusions that must be formed and welded, offering 140 MPa yield, 240 MPa tensile, 19 % elongation, 44 GPa modulus and 128 W/m·K conductivity at 1.78 g/cm³. Weldability scores 72 and machinability 93, but formability is still only 42 cold, service is capped at 120 °C and corrosion resistance scores 26. AZ31 is the nearest alternative where higher strength matters more than weld quality. ZM21 has a density of 1.78 g/cm³ (0.0643 lb/in³), lighter than 78% of magnesium alloy grades. It melts at 605°C (1,121 °F). ZM21 has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 61% of magnesium alloy grades. Elongation at break is 19% and the elastic modulus is 44 GPa (6.38 Msi).
What is ZM21 used for?
- sheet stampings
- extruded sections
- formed components
Advantages
- Ductile — tolerates forming and impact — 19%, better than 98% of magnesium alloy grades
- Tough — resists crack growth — 19 MPa·√m (17.3 ksi·√in), better than 98% of magnesium alloy grades
- Conducts heat well — 128 W/m·K (74 BTU/hr·ft·°F), better than 93% of magnesium alloy grades
- High electrical conductivity — 29 % IACS, better than 91% of magnesium alloy grades
- Forms and bends easily — 42/100, better than 91% of magnesium alloy grades
Limitations
- High embodied carbon — 36 kg CO₂/kg, worse than 93% of magnesium alloy grades
- Limited service temperature — 120°C (248 °F), worse than 78% of magnesium alloy grades
ZM21 properties
Typical room-temperature values for ZM21-O; bars are the position among magnesium alloy grades.
Physical3
ZM21 has a density of 1.78 g/cm³ (0.0643 lb/in³), lighter than 78% of magnesium alloy grades. It melts at 605°C (1,121 °F).
Mechanical14
ZM21 has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 61% of magnesium alloy grades. Elongation at break is 19% and the elastic modulus is 44 GPa (6.38 Msi).
Thermal6
ZM21 is rated for continuous service to 120°C (248 °F). It conducts heat at 128 W/m·K (74 BTU/hr·ft·°F), better than 93% of magnesium alloy grades. Thermal expansion is 26 µm/m·K (14.4 µin/in·°F).
Electrical3
ZM21 conducts electricity at 29 % IACS, better than 91% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (26/100), better than 74% of magnesium alloy grades.
Sustainability4
Producing a kilogram of ZM21 takes about 350 MJ of energy and emits 36 kg of CO₂ — more than 74% of magnesium alloy grades. Typical recycled content is 30%.
Manufacturability8
ZM21's machinability is excellent (93/100, worse than 78% of magnesium alloy grades); weldability very good (72/100); formability fair (42/100).
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. ZM21 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ZM21
Is ZM21 easy to machine?
Machines faster than any other structural metal — sharp tools, high speed, generous rake, no coolant mist on fine chips; collect and keep dry chips away from water and sparks (fire risk).
Can ZM21 be welded?
Aluminium-free chemistry gives good TIG/MIG weldability with ZM21 or AZ61/AZ92 filler; use argon, clean oxide, preheat thick sections and stress relieve to avoid distortion.
Can ZM21 be formed, bent or molded?
Cold-bend on generous radii only (≥5t); best results warm-forming at 200–300 °C where elongation exceeds 40 % — O temper for deep draws, H24 for shallow forms and rollforming.
ZM21 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 solid-solution strengthener | 1.75 – 2.5 | 2 |
| Mniron control and corrosion improvement | 0.6 – 1.4 | 1 |
| Alimpurity limit | ≤ 0.05 | |
| Siimpurity limit | ≤ 0.05 | |
| Cuimpurity limit | ≤ 0.05 | |
| Fecritical for corrosion | ≤ 0.01 | |
| Nicritical for corrosion | ≤ 0.01 | |
| Others (each)total 0.30 max | ≤ 0.05 | |
| Mg | balance |
What surface finishes work on ZM21?
Chromate-free conversion coating (ASTM D1732) or Mg anodize (HAE/Dow 17/PEO) plus epoxy primer and topcoat; never leave bare in humid or salt service and insulate all steel/CFRP joints.
Equivalent designations
Standards and trade names that resolve to Magnesium Alloy ZM21 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- MgZn2Mn1
- ISO
- ISO-WD32350
How much does ZM21 cost?
ZM21 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.
ZM21 — frequently asked
What is ZM21 used for?
ZM21 is typically used for sheet stampings, extruded sections and formed components. In short: best-welding wrought magnesium; aluminium-free Zn-Mn sheet alloy; good warm formability.
What is the yield strength of ZM21?
ZM21 has a typical yield strength of 140 MPa (20.3 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 61% of magnesium alloy grades. Strength varies by condition: see the 3 listed tempers.
Is ZM21 easy to machine?
Yes — machinability is rated excellent (93/100, worse than 78% of magnesium alloy grades). Machines faster than any other structural metal — sharp tools, high speed, generous rake, no coolant mist on fine chips; collect and keep dry chips away from water and sparks (fire risk).
Can ZM21 be welded?
Yes — weldability is rated very good (72/100). Aluminium-free chemistry gives good TIG/MIG weldability with ZM21 or AZ61/AZ92 filler; use argon, clean oxide, preheat thick sections and stress relieve to avoid distortion.
What surface finishes work on ZM21?
Chromate-free conversion coating (ASTM D1732) or Mg anodize (HAE/Dow 17/PEO) plus epoxy primer and topcoat; never leave bare in humid or salt service and insulate all steel/CFRP joints.
Can ZM21 be formed, bent or molded?
Cold-bend on generous radii only (≥5t); best results warm-forming at 200–300 °C where elongation exceeds 40 % — O temper for deep draws, H24 for shallow forms and rollforming.
What is the maximum service temperature of ZM21?
ZM21 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 ZM21-O and ZM21-H24?
O is the default condition — pick for maximum room-temperature and warm press formability — deep drawn, stretch-formed or bent panels. H24: standard structural sheet temper: higher yield strength and stiffness-per-gauge with usable warm formability. Yield strength is 140 MPa in O versus 195 MPa in H24.
How much does ZM21 cost?
ZM21 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
- ISO 3116 — Magnesium and magnesium alloys, wrought products (MgZn2Mn1 / WD32350) — ISO (2019)
- ASM Specialty Handbook: Magnesium and Magnesium Alloys — ASM International (1999)
- ASM Handbook, Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Wrought magnesium sheet and extrusion alloy data (ZM21/AZ31B) — Magnesium Elektron / Luxfer MEL Technologies (2021)
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.