Magnesium Alloy MgMn2-O (Annealed)
Temper
UNS M15100 · ASTM M1A
Pick for maximum warm formability and for parts that will be extensively welded or deep-drawn at 250–350 °C.
Values for the O condition
Other MgMn2 tempers and conditions
MgMn2 is listed in 4 conditions; see the grade overview at MgMn2.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OThis page Annealed | Pick for maximum warm formability and for parts that will be extensively welded or deep-drawn at 250–350 °C. | 105 | 220 | 15 | 40 HB | 34 % IACS |
as-forged bar stock and die forgings | For press forgings and hand forgings where uniform fine grain and weld repairability are required. | 160 | 250 | 10 | 47 HB | 33 % IACS |
FDefault As fabricated | Standard stocked condition for M1A/MgMn2 extrusions — best combination of weldability, corrosion behaviour and moderate strength. | 180 | 255 | 12 | 44 HB | — |
Strain hardened and partially annealed, half hard | Use where flat sheet stiffness and higher yield strength matter more than forming ductility. | 180 | 250 | 6 | 48 HB | 33 % IACS |
What is MgMn2-O?
MgMn2-O is MgMn2 in the O temper — pick for maximum warm formability and for parts that will be extensively welded or deep-drawn at 250–350 °C. MgMn2-O has a yield strength of 105 MPa (15.2 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 87% of magnesium alloy grades. Elongation at break is 15% and the elastic modulus is 45 GPa (6.53 Msi). MgMn2-O has a density of 1.76 g/cm³ (0.0636 lb/in³), lighter than 94% of magnesium alloy grades. It melts at 648°C (1,198 °F). F is the default condition FabDigit quotes; O is available on request or by drawing note.
Advantages
- High electrical conductivity — 34 % IACS, better than 100% of magnesium alloy grades
- Readily welded — 90/100, better than 99% of magnesium alloy grades
- Conducts heat well — 138 W/m·K (79.7 BTU/hr·ft·°F), better than 98% of magnesium alloy grades
- Good corrosion resistance — 32/100, better than 96% of magnesium alloy grades
- Tough — resists crack growth — 17 MPa·√m (15.5 ksi·√in), better than 94% of magnesium alloy grades
Limitations
- Low strength — 105 MPa (15.2 ksi), worse than 87% of magnesium alloy grades
MgMn2-O properties
Typical room-temperature values for MgMn2-O; 20 are specific to this condition. Other listed values are MgMn2 reference data and may not represent this condition. Bars are the position among magnesium alloy grades.
Physical3
MgMn2-O has a density of 1.76 g/cm³ (0.0636 lb/in³), lighter than 94% of magnesium alloy grades. It melts at 648°C (1,198 °F).
Mechanical13
MgMn2-O has a yield strength of 105 MPa (15.2 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 87% of magnesium alloy grades. Elongation at break is 15% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
MgMn2-O is rated for continuous service to 150°C (302 °F). It conducts heat at 138 W/m·K (79.7 BTU/hr·ft·°F), better than 98% of magnesium alloy grades. Thermal expansion is 26 µm/m·K (14.4 µin/in·°F).
Electrical3
MgMn2-O conducts electricity at 34 % IACS, better than 100% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), better than 96% of magnesium alloy grades.
Sustainability4
Producing a kilogram of MgMn2-O takes about 340 MJ of energy and emits 27 kg of CO₂ — more than 59% of magnesium alloy grades. Typical recycled content is 20%.
Manufacturability7
MgMn2-O's machinability is excellent (94/100, worse than 75% of magnesium alloy grades); weldability excellent (90/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with MgMn2-O
Is MgMn2 easy to machine?
Machines faster than any other structural metal — use sharp, high-rake, well-polished tools, generous chip clearance, no water-based coolant on fine chips, and keep a class-D extinguisher and swarf management plan for fire risk.
Can MgMn2 be welded?
Excellent for GTAW/GMAW with argon or Ar-He and EZ33A/M1A-type filler; the absence of Al and Zn means no post-weld stress-relief cracking, so it is the go-to grade for welded magnesium assemblies (light stress relief ~260 °C only for tight tolerances).
Can MgMn2 be formed, bent or molded?
Cold forming is very limited by the HCP structure; bend, draw and stretch at 230–350 °C with heated tooling, and use generous bend radii (≥5t cold, ≈2t hot).
What surface finishes work on MgMn2?
Never leave bare in service — apply chromate-free conversion coating, Dow 17/HAE anodic or PEO coating plus epoxy primer, and insulate all steel/aluminium fasteners with washers or sealant to prevent galvanic corrosion.
MgMn2 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 |
|---|---|---|
| Mnprincipal alloying element; ties up Fe as harmless intermetallics | 1.2 – 2 | 1.5 |
| Alimpurity limit | ≤ 0.3 | — |
| Znimpurity limit | ≤ 0.3 | — |
| Si | ≤ 0.1 | — |
| Cukept low for corrosion resistance | ≤ 0.05 | — |
| Nikept low for corrosion resistance | ≤ 0.01 | — |
| Fecontrolled by Mn addition | ≤ 0.03 | — |
| Ca | ≤ 0.3 | — |
| Others (each)total 0.30 max | ≤ 0.05 | — |
| Mg | balance | — |
MgMn2-O — frequently asked
What is MgMn2-O used for?
MgMn2-O is typically used for corrosion-resistant sheet and tube, lightly loaded structural parts and welded assemblies. In short: best-welding wrought magnesium; aluminium-free, low-strength grade; fastest-machining structural metal.
What is the yield strength of MgMn2-O?
MgMn2-O has a typical yield strength of 105 MPa (15.2 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 87% of magnesium alloy grades. Strength varies by condition: see the 4 listed tempers.
Is MgMn2-O easy to machine?
Yes — machinability is rated excellent (94/100, worse than 75% of magnesium alloy grades). Machines faster than any other structural metal — use sharp, high-rake, well-polished tools, generous chip clearance, no water-based coolant on fine chips, and keep a class-D extinguisher and swarf management plan for fire risk.
Can MgMn2-O be welded?
Yes — weldability is rated excellent (90/100). Excellent for GTAW/GMAW with argon or Ar-He and EZ33A/M1A-type filler; the absence of Al and Zn means no post-weld stress-relief cracking, so it is the go-to grade for welded magnesium assemblies (light stress relief ~260 °C only for tight tolerances).
What surface finishes work on MgMn2-O?
Never leave bare in service — apply chromate-free conversion coating, Dow 17/HAE anodic or PEO coating plus epoxy primer, and insulate all steel/aluminium fasteners with washers or sealant to prevent galvanic corrosion.
Can MgMn2-O be formed, bent or molded?
Cold forming is very limited by the HCP structure; bend, draw and stretch at 230–350 °C with heated tooling, and use generous bend radii (≥5t cold, ≈2t hot).
What is the maximum service temperature of MgMn2-O?
MgMn2-O 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 MgMn2-F and MgMn2-O?
F is the default condition — standard stocked condition for M1A/MgMn2 extrusions — best combination of weldability, corrosion behaviour and moderate strength. O: pick for maximum warm formability and for parts that will be extensively welded or deep-drawn at 250–350 °C. Yield strength is 180 MPa in F versus 105 MPa in O.
Sources
- ISO 3116 — Magnesium and magnesium alloys — Wrought magnesium alloys — ISO (2019)
- ASTM B107/B107M — Magnesium-Alloy Extruded Bars, Rods, Profiles, Tubes and Wire — ASTM International (2021)
- ASTM B91 — Magnesium-Alloy Forgings — ASTM International (2017)
- ASTM B275 — Codification of Certain Nonferrous Metals and Alloys, Cast and Wrought — ASTM International (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Magnesium alloys) — ASM International (1990)
- ASM Specialty Handbook — Magnesium and Magnesium Alloys — ASM International (1999)
- ASM Handbook Vol. 13B — Corrosion: Materials (Corrosion of Magnesium and Magnesium Alloys) — ASM International (2005)
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.