Aluminum LM25
BS LM25 · EN AlSi7Mg
LM25 is the BS 1490 Al-Si7Mg hypoeutectic casting alloy, equivalent to EN AC-42100, A356 and ZL101A, poured by sand, gravity-die and low-pressure casting.
Values for the T6 condition
LM25 tempers and conditions
LM25 is supplied in 5 conditions, soft to hard. T6 is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Cheapest condition for low-stress, leak-tight housings where dimensional stability after machining is not critical. | 85 | 150 | 3 | 60 HB | 40 % IACS |
Solution heat treated and stabilised | Dimensionally stable, ductile condition for castings that will see elevated temperature or need stress relief before precision machining. | 105 | 180 | 4 | 65 HB | 41 % IACS |
solution heat treated and naturally aged | Choose when maximum ductility and impact resistance matter more than strength (e.g. crash or bolted-joint castings). | 110 | 200 | 8 | 65 HB | 36 % IACS |
artificially aged from the as-cast condition | Low-distortion, low-cost strengthening (no quench) for parts that must hold tight dimensions after machining. | 135 | 180 | 1.5 | 75 HB | 40 % IACS |
T6Default Solution heat treated and artificially aged | Standard structural condition: highest strength and hardness for wheels, suspension and pressure-tight housings. | 215 | 250 | 3 | 95 HB | 39 % IACS |
What is LM25?
LM25 is the BS 1490 Al-Si7Mg hypoeutectic casting alloy, equivalent to EN AC-42100, A356 and ZL101A, poured by sand, gravity-die and low-pressure casting. Solution treatment plus artificial ageing (TF/T6) gives typical values of 215 MPa yield, 250 MPa tensile, 95 HB and 151 W/m·K, with good corrosion resistance, weldability and pressure-tightness, which suits wheels, intake and pump housings and thin-wall aircraft and instrument casings. Elongation is only 3%, fracture toughness is modest, and the alloy is sensitive to casting defects such as shrinkage porosity and oxide inclusions. The 7% silicon darkens anodic films, ruling out decorative bright finishes, and service should stay below about 150 °C. LM25 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 555°C (1,031 °F). LM25 has a yield strength of 215 MPa (31.2 ksi) and a tensile strength of 250 MPa (36.3 ksi) — stronger than 58% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
What is LM25 used for?
- Wheel rims
- Aerospace castings
- Intake manifolds
- Pump housings
- Instrument and avionics housings
- Thin-wall complex gearbox covers
- Pressure-tight valve bodies
Limitations
- Limited formability — 10/100, worse than 80% of aluminum grades
- Limited ductility — 3%, worse than 79% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
LM25 properties
Typical room-temperature values for LM25-T6; bars are the position among aluminum grades.
Physical3
LM25 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 555°C (1,031 °F).
Mechanical13
LM25 has a yield strength of 215 MPa (31.2 ksi) and a tensile strength of 250 MPa (36.3 ksi) — stronger than 58% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
LM25 is rated for continuous service to 150°C (302 °F). It conducts heat at 151 W/m·K (87.2 BTU/hr·ft·°F), better than 63% of aluminum grades. Thermal expansion is 22 µm/m·K (12.2 µin/in·°F).
Electrical3
LM25 conducts electricity at 39 % IACS, better than 65% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 71% of aluminum grades.
Sustainability4
Producing a kilogram of LM25 takes about 190 MJ of energy and emits 12 kg of CO₂ — less than 89% of aluminum grades. Typical recycled content is 50%.
Manufacturability8
LM25's machinability is good (65/100, better than 62% of aluminum grades); weldability very good (75/100); 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 aluminum family
Yield strength against density for every aluminum grade FabDigit runs. LM25 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with LM25
Is LM25 easy to machine?
Machines cleanly with polished-flute carbide or PCD tooling at high speed; eutectic silicon is abrasive, so use PCD for long runs and flood coolant to avoid built-up edge.
Can LM25 be welded?
Readily TIG/MIG welded with 4043 (or 4047) filler; weld before heat treatment or re-solution/age afterwards, since welding locally overages T6 material.
Can LM25 be formed, bent or molded?
Excellent fluidity and low hot-tearing for sand, gravity-die and low-pressure casting; feed heavy sections and Sr-modify plus grain-refine for full T6 ductility, and avoid heavy T6 quench distortion on thin frames.
Manufacturability
The process limits FabDigit applies to LM25. Every LM25 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Good65 / 100 |
|---|---|
| ISO material group | N.1 |
| Cutting speed (rough / finish) | 350 / 420 m/min |
| Minimum wall | 0.5 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 8× diameter |
| Best surface (machined / polished) | Ra 0.8 / — |
| Hardenable after machining | No |
LM25 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 |
|---|---|---|
| Si | 6.5 – 7.5 | 7 |
| MgSr or Na modified in most foundries | 0.2 – 0.45 | 0.35 |
| Fe0.50 max sand cast; 0.60 max reported for some pressure-tight grades | ≤ 0.5 | 0.2 |
| Cu | ≤ 0.2 | 0.05 |
| Mn | ≤ 0.3 | 0.05 |
| Ni | ≤ 0.1 | |
| Zn | ≤ 0.1 | |
| Pb | ≤ 0.1 | |
| Sn | ≤ 0.05 | |
| Tigrain refiner (Al-Ti-B) | ≤ 0.2 | 0.12 |
| Others (each)total 0.15 max | ≤ 0.05 | |
| Al | balance |
What surface finishes work on LM25?
Takes chromate/anodic protective coatings and paint well; hard anodize gives a dark grey film because of the 7 % Si, and polishing leaves a slight silicon-particle haze.
Surface treatments FabDigit runs on aluminum parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Conversion Coating
PVD Coating
Equivalent designations
Standards and trade names that resolve to Aluminum LM25 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- AlSi7Mg
- BS
- 1490 LM25
How much does LM25 cost?
LM25 is a standard-cost aluminum ($$), cheaper than about 81% 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.
LM25 — frequently asked
What is LM25 used for?
LM25 is typically used for wheel rims, aerospace castings, intake manifolds, pump housings, instrument and avionics housings and thin-wall complex gearbox covers. In short: BS heat-treatable Al-Si-Mg cast; A356 equivalent.
What is the yield strength of LM25?
LM25 has a typical yield strength of 215 MPa (31.2 ksi) and a tensile strength of 250 MPa (36.3 ksi) — stronger than 58% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is LM25 easy to machine?
Reasonably — machinability is rated good (65/100, better than 62% of aluminum grades). Machines cleanly with polished-flute carbide or PCD tooling at high speed; eutectic silicon is abrasive, so use PCD for long runs and flood coolant to avoid built-up edge.
Can LM25 be welded?
Yes — weldability is rated very good (75/100). Readily TIG/MIG welded with 4043 (or 4047) filler; weld before heat treatment or re-solution/age afterwards, since welding locally overages T6 material.
What surface finishes work on LM25?
Takes chromate/anodic protective coatings and paint well; hard anodize gives a dark grey film because of the 7 % Si, and polishing leaves a slight silicon-particle haze.
Can LM25 be formed, bent or molded?
Excellent fluidity and low hot-tearing for sand, gravity-die and low-pressure casting; feed heavy sections and Sr-modify plus grain-refine for full T6 ductility, and avoid heavy T6 quench distortion on thin frames.
What is the maximum service temperature of LM25?
LM25 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 LM25-T6 and LM25-F?
T6 is the default condition — standard structural condition: highest strength and hardness for wheels, suspension and pressure-tight housings. F: cheapest condition for low-stress, leak-tight housings where dimensional stability after machining is not critical. Yield strength is 215 MPa in T6 versus 85 MPa in F.
How much does LM25 cost?
LM25 is a standard-cost aluminum ($$), cheaper than about 81% 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.
Can FabDigit make parts in LM25?
Yes — LM25 is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- BS 1490 — Aluminium and aluminium alloy ingots and castings for general engineering purposes — BSI (1988)
- BS EN 1706 — Aluminium and aluminium alloys, castings (EN AC-42100 AlSi7Mg0,3) — CEN (2020)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (A356 data) — ASM International (1990)
- ASM Handbook Vol. 19 — Fatigue and Fracture (cast Al-Si-Mg alloys) — ASM International (1996)
- GB/T 1173 — (ZL101A) — SAC (2013)
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.