Magnesium Alloy AZ91C
ASTM AZ91C · UNS M11914
AZ91C is the sand and permanent-mold casting variant of the AZ91 Mg-Al-Zn family (UNS M11914), available as-cast (F) and in T4, T5 and T6 conditions.
Reference datasheet — AZ91C 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
AZ91C tempers and conditions
AZ91C is supplied in 4 conditions, soft to hard. F is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated and naturally aged | Choose for maximum ductility and impact toughness in cast magnesium parts, at the cost of low yield strength. | 90 | 275 | 14 | 55 HB | 68 W/m·K |
FDefault As fabricated | Default foundry condition: lowest cost, adequate for lightly loaded housings and covers where no heat treatment is justified. | 97 | 165 | 2.5 | 60 HB | 72 W/m·K |
Cooled from hot working and artificially aged | Low-cost stabilizing age used to raise yield strength and dimensional stability slightly without a full solution cycle. | 110 | 165 | 2 | 65 HB | — |
Solution heat treated and artificially aged | Highest-strength condition for structural sand/permanent-mold castings where yield strength and hardness matter more than ductility. | 145 | 275 | 6 | 70 HB | 72 W/m·K |
What is AZ91C?
AZ91C is the sand and permanent-mold casting variant of the AZ91 Mg-Al-Zn family (UNS M11914), available as-cast (F) and in T4, T5 and T6 conditions. It is used for low-volume, large or geometrically awkward castings that cannot be die cast, and unlike die-cast AZ91 it welds well (weldability score 70) for fabrication and repair. As-cast properties are modest — 97 MPa yield, 165 MPa tensile, 2.5% elongation, 60 HB — with 72 W/m·K conductivity and a 120 °C service ceiling. Corrosion resistance is limited by standard-purity chemistry, so high-purity AZ91E is preferred for exposed structural castings. AZ91C 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). AZ91C has a yield strength of 97 MPa (14.1 ksi) and a tensile strength of 165 MPa (23.9 ksi) — weaker than 90% of magnesium alloy grades. Elongation at break is 2.5% and the elastic modulus is 45 GPa (6.53 Msi).
What is AZ91C used for?
- Sand-cast gearbox and machinery housings
- Permanent-mold pump bodies
- Instrument and avionics housings
- Prototype castings ahead of die-cast tooling
- Equipment brackets and covers
- Low-volume structural castings
Limitations
- Limited ductility — 2.5%, worse than 97% of magnesium alloy grades
- Low strength — 97 MPa (14.1 ksi), worse than 90% 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
AZ91C properties
Typical room-temperature values for AZ91C-F; bars are the position among magnesium alloy grades.
Physical3
AZ91C 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).
Mechanical13
AZ91C has a yield strength of 97 MPa (14.1 ksi) and a tensile strength of 165 MPa (23.9 ksi) — weaker than 90% of magnesium alloy grades. Elongation at break is 2.5% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
AZ91C 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
AZ91C conducts electricity at 12 % IACS, worse than 78% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), worse than 77% of magnesium alloy grades.
Sustainability4
Producing a kilogram of AZ91C takes about 355 MJ of energy and emits 28 kg of CO₂ — more than 85% of magnesium alloy grades. Typical recycled content is 35%.
Manufacturability8
AZ91C's machinability is excellent (95/100, better than 54% of magnesium alloy grades); weldability very good (70/100); formability not recommended (12/100).
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. AZ91C is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AZ91C
Is AZ91C easy to machine?
Outstanding machinability — high speeds, low cutting forces, sharp positive-rake tools and dry or oil (never water-based) coolant; collect and control fine chips/dust because of fire risk.
Can AZ91C be welded?
Readily GTAW/GMAW welded in inert gas with AZ92A or AZ101A filler; preheat thin sections, avoid Zn-rich fillers on thick joints and stress relieve (~260 °C) to prevent SCC.
Can AZ91C be formed, bent or molded?
Casting alloy only — excellent sand and permanent-mold castability with SF6-free cover gas or flux; needs generous fillets and controlled solidification to avoid microporosity, and no cold forming.
AZ91C 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 | 8.1 – 9.3 | 8.7 |
| Zn | 0.4 – 1 | 0.7 |
| Mn0.13 % min per ASTM B80 | ≥ 0.13 | 0.2 |
| Si | ≤ 0.3 | |
| Cu | ≤ 0.1 | |
| Ni | ≤ 0.01 | |
| Others (total) | ≤ 0.3 | |
| Mg | balance |
What surface finishes work on AZ91C?
Not sulfuric-anodizable: apply chromate/fluoride or fluoride-free conversion coating, Dow 17/HAE or PEO, then epoxy primer and topcoat; insulate all steel/brass fasteners to avoid galvanic attack.
Equivalent designations
Standards and trade names that resolve to Magnesium Alloy AZ91C in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- M11914
How much does AZ91C cost?
AZ91C 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.
AZ91C — frequently asked
What is AZ91C used for?
AZ91C is typically used for sand-cast gearbox and machinery housings, permanent-mold pump bodies, instrument and avionics housings, prototype castings ahead of die-cast tooling, equipment brackets and covers and low-volume structural castings. In short: weldable AZ91 casting grade; sand and permanent-mold route; heat-treatable to T6.
What is the yield strength of AZ91C?
AZ91C has a typical yield strength of 97 MPa (14.1 ksi) and a tensile strength of 165 MPa (23.9 ksi) — weaker than 90% of magnesium alloy grades. Strength varies by condition: see the 4 listed tempers.
Is AZ91C easy to machine?
Yes — machinability is rated excellent (95/100, better than 54% of magnesium alloy grades). Outstanding machinability — high speeds, low cutting forces, sharp positive-rake tools and dry or oil (never water-based) coolant; collect and control fine chips/dust because of fire risk.
Can AZ91C be welded?
Yes — weldability is rated very good (70/100). Readily GTAW/GMAW welded in inert gas with AZ92A or AZ101A filler; preheat thin sections, avoid Zn-rich fillers on thick joints and stress relieve (~260 °C) to prevent SCC.
What surface finishes work on AZ91C?
Not sulfuric-anodizable: apply chromate/fluoride or fluoride-free conversion coating, Dow 17/HAE or PEO, then epoxy primer and topcoat; insulate all steel/brass fasteners to avoid galvanic attack.
Can AZ91C be formed, bent or molded?
Casting alloy only — excellent sand and permanent-mold castability with SF6-free cover gas or flux; needs generous fillets and controlled solidification to avoid microporosity, and no cold forming.
What is the maximum service temperature of AZ91C?
AZ91C 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 AZ91C-F and AZ91C-T6?
F is the default condition — default foundry condition: lowest cost, adequate for lightly loaded housings and covers where no heat treatment is justified. T6: highest-strength condition for structural sand/permanent-mold castings where yield strength and hardness matter more than ductility. Yield strength is 97 MPa in F versus 145 MPa in T6.
How much does AZ91C cost?
AZ91C 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 B80 — Magnesium-Alloy Sand Castings — ASTM International (2015)
- ASTM B199 — Magnesium-Alloy Permanent Mold Castings — ASTM International (2019)
- ASTM B661 — Heat Treatment of Magnesium Alloys — ASTM International (2019)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (Magnesium) — ASM International (1990)
- ASM Handbook Vol. 15 — Casting (Magnesium Foundry Practice) — ASM International (2008)
- ASM Specialty Handbook: Magnesium and Magnesium Alloys — ASM International (1999)
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.