Magnesium Alloy M1A · temper · default condition
Magnesium Alloy M1A-O
Properties of the O condition, compared with the other M1A tempers.
Softest, most formable condition — pick for deep forming, bending and welded fabrications from sheet.
What is M1A-O?
M1A-O is M1A in the O temper — softest, most formable condition — pick for deep forming, bending and welded fabrications from sheet. M1A-O has a yield strength of 115 MPa (16.7 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 80% of magnesium alloy grades. Elongation at break is 12% and the elastic modulus is 45 GPa (6.53 Msi). M1A-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).
Advantages
- Conducts heat well — 138 W/m·K (79.7 BTU/hr·ft·°F), better than 98% of magnesium alloy grades
- Forms and bends easily — 55/100, better than 98% of magnesium alloy grades
- High electrical conductivity — 33 % IACS, better than 97% of magnesium alloy grades
- Readily welded — 88/100, better than 96% of magnesium alloy grades
Limitations
- Low strength — 115 MPa (16.7 ksi), worse than 80% of magnesium alloy grades
M1A-O properties
Typical room-temperature values for M1A-O — 10 properties are specific to this condition; the rest are grade-level values shared by every M1A temper. Each bar shows where the value sits among the magnesium alloy grades in FabDigit's library — further right is higher.
Physical3
M1A-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
M1A-O has a yield strength of 115 MPa (16.7 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 80% of magnesium alloy grades. Elongation at break is 12% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
M1A-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
M1A-O conducts electricity at 33 % IACS, better than 97% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (28/100), better than 78% of magnesium alloy grades.
Sustainability4
Producing a kilogram of M1A-O takes about 350 MJ of energy and emits 32 kg of CO₂ — more than 74% of magnesium alloy grades. Typical recycled content is 25%.
Manufacturability8
M1A-O's machinability is excellent (96/100, better than 87% of magnesium alloy grades); weldability excellent (88/100); formability good (55/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other M1A tempers and conditions
M1A is also supplied in 2 other conditions. The full side-by-side table is on the M1A overview.
- ODefaultSoftest, most formable condition — pick for deep forming, bending and welded fabrications from sheet.115 MPa yield · 44 HB
- H24Hard-rolled sheet for flat panels and skins where higher yield strength matters more than bend radius.180 MPa yield · 50 HB
- FStandard condition for ASTM B107 extrusions and B91 forgings — best strength/ductility combination available in M1A.179 MPa yield · 44 HB
Working with M1A-O
Is M1A easy to machine?
Cuts faster and with lower power than any other structural metal — use sharp high-rake tools, high speed, no water-based coolant, and keep fine chips/dust controlled to avoid fire.
Can M1A be welded?
Excellent GTAW/GMAW weldability with EZ33A or M1A/AZ61A filler under argon or helium; Mg-Mn is not susceptible to stress-corrosion cracking, so post-weld stress relief is usually unnecessary.
Can M1A be formed, bent or molded?
Cold formability is limited by the HCP structure — warm form at 200–350 °C for tight bends, deep draws and stretch forming; anneal 340–370 °C between passes.
What surface finishes work on M1A?
Do not sulfuric-anodize; apply chromate/fluoride conversion or magnesium anodic coatings (Dow 17, HAE, Keronite) followed by epoxy primer/paint, and isolate from steel, brass and carbon fibre with sealants or non-metallic washers.
M1A 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 |
|---|---|---|
| Mnmanganese is the only intentional addition | 1.2 – 2 | 1.5 |
| Alimpurity limit | ≤ 0.3 | — |
| Ca | ≤ 0.3 | — |
| Cu | ≤ 0.05 | — |
| Si | ≤ 0.1 | — |
| Nikept very low for corrosion resistance | ≤ 0.01 | — |
| Others (each)total 0.30 max | ≤ 0.05 | — |
| Mg | balance | — |
M1A-O — frequently asked
What is M1A-O used for?
M1A-O is typically used for sacrificial anodes for water heaters and tanks, automotive trim and covers, welded magnesium sheet assemblies, corrosion-exposed marine hardware, formed housings and panels and extruded low-stress profiles. In short: weldable magnesium sheet.
What is the yield strength of M1A-O?
M1A-O has a typical yield strength of 115 MPa (16.7 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 80% of magnesium alloy grades. Strength varies by condition: see the 3 listed tempers.
Is M1A-O easy to machine?
Yes — machinability is rated excellent (96/100, better than 87% of magnesium alloy grades). Cuts faster and with lower power than any other structural metal — use sharp high-rake tools, high speed, no water-based coolant, and keep fine chips/dust controlled to avoid fire.
Can M1A-O be welded?
Yes — weldability is rated excellent (88/100). Excellent GTAW/GMAW weldability with EZ33A or M1A/AZ61A filler under argon or helium; Mg-Mn is not susceptible to stress-corrosion cracking, so post-weld stress relief is usually unnecessary.
What surface finishes work on M1A-O?
Do not sulfuric-anodize; apply chromate/fluoride conversion or magnesium anodic coatings (Dow 17, HAE, Keronite) followed by epoxy primer/paint, and isolate from steel, brass and carbon fibre with sealants or non-metallic washers.
Can M1A-O be formed, bent or molded?
Cold formability is limited by the HCP structure — warm form at 200–350 °C for tight bends, deep draws and stretch forming; anneal 340–370 °C between passes.
What is the maximum service temperature of M1A-O?
M1A-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 M1A-O and M1A-H24?
O is the default condition — softest, most formable condition — pick for deep forming, bending and welded fabrications from sheet. H24: hard-rolled sheet for flat panels and skins where higher yield strength matters more than bend radius. Yield strength is 115 MPa in O versus 180 MPa in H24.
Can FabDigit make parts in M1A-O?
Yes — M1A-O is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B107/B107M — Magnesium-Alloy Extruded Bars, Rods, Profiles, Tubes and Wire — ASTM International (2021)
- ASTM B90/B90M — Magnesium-Alloy Sheet and Plate — ASTM International (2021)
- ASTM B91 — Magnesium-Alloy Forgings — ASTM International (2017)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (Magnesium alloys) — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion of Magnesium and Magnesium Alloys — ASM International (2005)
- ASTM D1732 / MIL-M-3171 — Magnesium conversion and anodic coatings — ASTM / US DoD (2019)
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.