Magnesium Alloy AS41B-F
Grade
ASTM AS41 · EN MC21320, MgAl4Si
AS41B-F = high-purity (low Fe/Ni/Cu) composition, as die cast
Choose the current high-purity composition (Fe ≤ 0.0035%, Ni ≤ 0.001%, Cu ≤ 0.015%) for automotive die castings; salt-spray rate approaches high-purity AZ91D at the same 140 MPa yield.
Values for the AS41B-F condition
Other AS41 tempers and conditions
AS41 is listed in 3 conditions; see the grade overview at AS41.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
FDefault As fabricated | Use the standard as-die-cast state, with no heat treatment after high-pressure die casting, for housings in normal warm service to 150 °C at 140 MPa yield and 240 MPa tensile. | 140 | 240 | 6 | 60 HB | 68 W/m·K |
Commercial-purity composition, as die cast | Use the older commercial-purity composition, with wider Fe/Ni/Cu limits, only in non-corrosive environments: mechanical properties match the high-purity version but salt-spray corrosion is ten times faster. | 140 | 240 | 6 | 60 HB | 14 % IACS |
AS41B-FThis page High-purity (low Fe/Ni/Cu) composition, as die cast | Choose the current high-purity composition (Fe ≤ 0.0035%, Ni ≤ 0.001%, Cu ≤ 0.015%) for automotive die castings; salt-spray rate approaches high-purity AZ91D at the same 140 MPa yield. | 140 | 240 | 6 | 60 HB | 14 % IACS |
What is AS41B-F?
AS41B-F is AS41 in the AS41B-F grade — choose the current high-purity composition (Fe ≤ 0.0035%, Ni ≤ 0.001%, Cu ≤ 0.015%) for automotive die castings; salt-spray rate approaches high-purity AZ91D at the same 140 MPa yield. AS41B-F 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 6% and the elastic modulus is 45 GPa (6.53 Msi). AS41B-F has a density of 1.77 g/cm³ (0.0639 lb/in³), lighter than 86% of magnesium alloy grades. It melts at 565°C (1,049 °F). F is the default condition FabDigit quotes; AS41B-F is available on request or by drawing note.
Advantages
- Good corrosion resistance — 33/100, better than 99% of magnesium alloy grades
Limitations
- Difficult to weld — 30/100, worse than 90% of magnesium alloy grades
- Poor heat conductor — 68 W/m·K (39.3 BTU/hr·ft·°F), worse than 81% of magnesium alloy grades
AS41B-F properties
Typical room-temperature values for AS41B-F; 20 are specific to this condition. Other listed values are AS41 reference data and may not represent this condition. Bars are the position among magnesium alloy grades.
Physical3
AS41B-F has a density of 1.77 g/cm³ (0.0639 lb/in³), lighter than 86% of magnesium alloy grades. It melts at 565°C (1,049 °F).
Mechanical14
AS41B-F 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 6% and the elastic modulus is 45 GPa (6.53 Msi).
Thermal6
AS41B-F is rated for continuous service to 150°C (302 °F). It conducts heat at 68 W/m·K (39.3 BTU/hr·ft·°F), worse than 81% of magnesium alloy grades. Thermal expansion is 26.1 µm/m·K (14.5 µin/in·°F).
Electrical3
AS41B-F conducts electricity at 14 % IACS, worse than 58% of magnesium alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (33/100), better than 99% of magnesium alloy grades.
Sustainability4
Producing a kilogram of AS41B-F takes about 320 MJ of energy and emits 30 kg of CO₂ — less than 74% of magnesium alloy grades. Typical recycled content is 35%.
Manufacturability8
AS41B-F's machinability is excellent (95/100, better than 54% of magnesium alloy grades); weldability poor (30/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AS41B-F
Is AS41 easy to machine?
Machinability is excellent: run high spindle speeds and heavy feeds with sharp, positive-rake tooling. Use ample mineral-oil cutting fluid or cut dry with fire precautions, because fine chips and dust are flammable; do not let chips accumulate in water-based emulsions.
Can AS41 be welded?
Die castings contain gas porosity, so fusion welding tends to produce pores and cracks. Small areas can be repair-welded locally by TIG or laser with AZ61 or AZ92 filler; for structural joints prefer self-pierce riveting, threaded inserts or adhesive bonding.
Can AS41 be formed, bent or molded?
Hot- or cold-chamber high-pressure die casting, with pouring temperature about 650–690 °C and die temperature 200–260 °C. The silicon content makes fluidity slightly lower than AZ91D, so raise gate velocity and die temperature for walls below 1.5 mm.
What surface finishes work on AS41?
Conventional sulphuric-acid anodizing is not applicable; use chromate or chrome-free conversion coatings, Dow 17 or HAE anodic treatment, or micro-arc oxidation, then epoxy primer and topcoat. Insulate fastener locations with isolating washers to prevent galvanic corrosion.
AS41 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 |
|---|---|---|
| AlAS41A: 3.5–5.0 | 3.7 – 4.8 | 4.2 |
| Siforms Mg2Si for creep resistance | 0.6 – 1.4 | 1 |
| MnFe control / corrosion | 0.35 – 0.6 | 0.4 |
| Zn | ≤ 0.1 | 0.05 |
| CuAS41A: 0.04 max | ≤ 0.02 | — |
| NiAS41A: 0.01 max | ≤ 0 | — |
| Fehigh-purity limit, Fe/Mn ratio controlled | ≤ 0 | — |
| Others (each) | ≤ 0.02 | — |
| Mg | balance | — |
AS41B-F — frequently asked
What is AS41B-F used for?
AS41B-F is typically used for engine blocks, transmission cases, crankcases and powertrain brackets. In short: creep-resistant die-cast magnesium; warm-running powertrain grade; machines faster than aluminium.
What is the yield strength of AS41B-F?
AS41B-F 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 AS41B-F easy to machine?
Yes — machinability is rated excellent (95/100, better than 54% of magnesium alloy grades). Machinability is excellent: run high spindle speeds and heavy feeds with sharp, positive-rake tooling. Use ample mineral-oil cutting fluid or cut dry with fire precautions, because fine chips and dust are flammable; do not let chips accumulate in water-based emulsions.
Can AS41B-F be welded?
Not readily — weldability is rated poor (30/100). Die castings contain gas porosity, so fusion welding tends to produce pores and cracks. Small areas can be repair-welded locally by TIG or laser with AZ61 or AZ92 filler; for structural joints prefer self-pierce riveting, threaded inserts or adhesive bonding.
What surface finishes work on AS41B-F?
Conventional sulphuric-acid anodizing is not applicable; use chromate or chrome-free conversion coatings, Dow 17 or HAE anodic treatment, or micro-arc oxidation, then epoxy primer and topcoat. Insulate fastener locations with isolating washers to prevent galvanic corrosion.
Can AS41B-F be formed, bent or molded?
Hot- or cold-chamber high-pressure die casting, with pouring temperature about 650–690 °C and die temperature 200–260 °C. The silicon content makes fluidity slightly lower than AZ91D, so raise gate velocity and die temperature for walls below 1.5 mm.
What is the maximum service temperature of AS41B-F?
AS41B-F 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 AS41-F and AS41A-F?
F is the default condition — use the standard as-die-cast state, with no heat treatment after high-pressure die casting, for housings in normal warm service to 150 °C at 140 MPa yield and 240 MPa tensile. AS41A-F: use the older commercial-purity composition, with wider Fe/Ni/Cu limits, only in non-corrosive environments: mechanical properties match the high-purity version but salt-spray corrosion is ten times faster. Yield strength is 140 MPa in F versus 140 MPa in AS41A-F.
Sources
- ASTM B94 — Standard Specification for Magnesium-Alloy Die Castings — ASTM International (2018)
- ASTM B93/B93M — Magnesium Alloys in Ingot Form for Sand, Permanent Mold, and Die Castings — ASTM International (2020)
- ASM Specialty Handbook: Magnesium and Magnesium Alloys — ASM International (1999)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
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.