Magnesium Alloy AZ91A
ASTM AZ91A · UNS M11910
AZ91A is the original die-casting composition of the Mg-Al-Zn AZ91 family (UNS M11910), supplied as-cast in the F condition.
Reference datasheet — AZ91A 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 F condition
AZ91A tempers and conditions
AZ91A is supplied in one standard condition, F. F is the default FabDigit quotes; the values on this page are for it.
What is AZ91A?
AZ91A is the original die-casting composition of the Mg-Al-Zn AZ91 family (UNS M11910), supplied as-cast in the F condition. It is chosen for thin-wall pressure die castings that need low mass and very free machining, with typical F properties of 150 MPa yield, 230 MPa tensile, 3% elongation, 63 HB and 72 W/m·K thermal conductivity. Limits are a 120 °C maximum service temperature, poor weldability on die castings (score 30) and modest corrosion resistance (score 22) that depends on tight Fe/Ni/Cu control. Higher-purity AZ91D is chemically equivalent in mechanical properties and is the usual replacement. AZ91A has a density of 1.81 g/cm³ (0.0654 lb/in³), heavier than 58% of magnesium alloy grades. It melts at 470°C (878 °F). AZ91A has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 230 MPa (33.4 ksi) — stronger than 59% of magnesium alloy grades. Elongation at break is 3% and the elastic modulus is 45 GPa (6.53 Msi).
What is AZ91A used for?
- Die-cast electronics and instrument housings
- General automotive die-cast parts
- Gearbox and transmission covers
- Power tool bodies
- Handheld equipment frames
- Non-structural enclosure covers
Limitations
- Low fracture toughness — 12 MPa·√m (10.9 ksi·√in), worse than 92% of magnesium alloy grades
- Difficult to weld — 30/100, worse than 90% of magnesium alloy grades
- Limited ductility — 3%, worse than 85% of magnesium alloy grades
- Limited service temperature — 120°C (248 °F), worse than 78% of magnesium alloy grades
- Low electrical conductivity — 12 % IACS, worse than 78% of magnesium alloy grades
AZ91A properties
Typical room-temperature values for AZ91A-F; bars are the position among magnesium alloy grades.
Physical3
AZ91A has a density of 1.81 g/cm³ (0.0654 lb/in³), heavier than 58% of magnesium alloy grades. It melts at 470°C (878 °F).
Mechanical14
AZ91A has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 230 MPa (33.4 ksi) — stronger than 59% of magnesium alloy grades. Elongation at break is 3% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
AZ91A is rated for continuous service to 120°C (248 °F). It conducts heat at 72 W/m·K (41.6 BTU/hr·ft·°F), worse than 69% of magnesium alloy grades. Thermal expansion is 26 µm/m·K (14.4 µin/in·°F).
Electrical3
AZ91A conducts electricity at 12 % IACS, worse than 78% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (22/100), worse than 57% of magnesium alloy grades.
Sustainability4
Producing a kilogram of AZ91A takes about 350 MJ of energy and emits 28 kg of CO₂ — more than 74% of magnesium alloy grades. Typical recycled content is 30%.
Manufacturability8
AZ91A's machinability is excellent (95/100, better than 54% of magnesium alloy grades); weldability poor (30/100); formability not recommended (10/100).
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. AZ91A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AZ91A
Is AZ91A easy to machine?
Outstanding machinability at high speed with sharp, high-rake tools and low cutting forces; use dry or mineral-oil coolant (never water-based) and manage fine chips/dust to avoid fire.
Can AZ91A be welded?
GTAW/GMAW with AZ92A or AZ101A filler is feasible on clean sand castings, but HPDC AZ91A blisters and porosity-cracks — repair welding is generally not recommended.
Can AZ91A be formed, bent or molded?
Excellent hot-chamber die-casting alloy: low latent heat, high fluidity, thin walls to ~1 mm; melt under SF6/SO2 or novel cover gas and keep Fe/Ni/Cu low to protect corrosion behaviour.
AZ91A 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 |
|---|---|---|
| Al | 8.3 – 9.7 | 9 |
| Zn | 0.35 – 1 | 0.7 |
| Mn0.13 % minimum per ASTM B94 | ≥ 0.13 | 0.2 |
| Si | ≤ 0.5 | |
| Cumain difference vs AZ91D (0.030 max) | ≤ 0.1 | |
| Ni | ≤ 0.03 | |
| Others (total) | ≤ 0.3 | |
| Mg | balance |
What surface finishes work on AZ91A?
Requires chromate or chrome-free conversion coating, Dow 17/HAE anodize or PEO plus epoxy/powder topcoat; isolate from steel and aluminium fasteners to prevent galvanic corrosion.
Equivalent designations
Standards and trade names that resolve to Magnesium Alloy AZ91A in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- M11910
- Also called
- AZ91A-F
How much does AZ91A cost?
AZ91A is a standard-cost magnesium alloy ($$), cheaper than about 71% 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.
AZ91A — frequently asked
What is AZ91A used for?
AZ91A is typically used for die-cast electronics and instrument housings, general automotive die-cast parts, gearbox and transmission covers, power tool bodies, handheld equipment frames and non-structural enclosure covers. In short: original AZ91 die-cast grade; fastest-machining structural metal; superseded by AZ91D.
What is the yield strength of AZ91A?
AZ91A has a typical yield strength of 150 MPa (21.8 ksi) and a tensile strength of 230 MPa (33.4 ksi) — stronger than 59% of magnesium alloy grades.
Is AZ91A easy to machine?
Yes — machinability is rated excellent (95/100, better than 54% of magnesium alloy grades). Outstanding machinability at high speed with sharp, high-rake tools and low cutting forces; use dry or mineral-oil coolant (never water-based) and manage fine chips/dust to avoid fire.
Can AZ91A be welded?
Not readily — weldability is rated poor (30/100). GTAW/GMAW with AZ92A or AZ101A filler is feasible on clean sand castings, but HPDC AZ91A blisters and porosity-cracks — repair welding is generally not recommended.
What surface finishes work on AZ91A?
Requires chromate or chrome-free conversion coating, Dow 17/HAE anodize or PEO plus epoxy/powder topcoat; isolate from steel and aluminium fasteners to prevent galvanic corrosion.
Can AZ91A be formed, bent or molded?
Excellent hot-chamber die-casting alloy: low latent heat, high fluidity, thin walls to ~1 mm; melt under SF6/SO2 or novel cover gas and keep Fe/Ni/Cu low to protect corrosion behaviour.
What is the maximum service temperature of AZ91A?
AZ91A 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.
How much does AZ91A cost?
AZ91A is a standard-cost magnesium alloy ($$), cheaper than about 71% 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
- ASTM B94 — Standard Specification for Magnesium-Alloy Die Castings — ASTM International (2018)
- ASTM B275 — Codification of Certain Nonferrous Metals and Alloys (UNS M11910) — ASTM International (2018)
- ASM Specialty Handbook: Magnesium and Magnesium Alloys — ASM International (1999)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — 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.