Aluminum LM25 · temper
Aluminum LM25-F
Properties of the F condition, compared with the other LM25 tempers.
Cheapest condition for low-stress, leak-tight housings where dimensional stability after machining is not critical.
What is LM25-F?
LM25-F is LM25 in the F temper — cheapest condition for low-stress, leak-tight housings where dimensional stability after machining is not critical. LM25-F has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 150 MPa (21.8 ksi) — weaker than 89% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi). LM25-F 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). T6 is the default condition FabDigit quotes; F is available on request or by drawing note.
Limitations
- Low strength — 85 MPa (12.3 ksi), worse than 89% of aluminum grades
- Limited formability — 10/100, worse than 81% of aluminum grades
- Limited ductility — 3%, worse than 79% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
LM25-F properties
Typical room-temperature values for LM25-F — 11 properties are specific to this condition; the rest are grade-level values shared by every LM25 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
LM25-F 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-F has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 150 MPa (21.8 ksi) — weaker than 89% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
LM25-F is rated for continuous service to 150°C (302 °F). It conducts heat at 155 W/m·K (89.6 BTU/hr·ft·°F), better than 71% of aluminum grades. Thermal expansion is 22 µm/m·K (12.2 µin/in·°F).
Electrical3
LM25-F conducts electricity at 40 % IACS, better than 72% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 71% of aluminum grades.
Sustainability4
Producing a kilogram of LM25-F 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-F's machinability is good (55/100, worse than 58% of aluminum grades); weldability very good (75/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other LM25 tempers and conditions
LM25 is also supplied in 4 other conditions. The full side-by-side table is on the LM25 overview.
- T6DefaultStandard structural condition: highest strength and hardness for wheels, suspension and pressure-tight housings.215 MPa yield · 95 HB
- TELow-distortion, low-cost strengthening (no quench) for parts that must hold tight dimensions after machining.135 MPa yield · 75 HB
- TBChoose when maximum ductility and impact resistance matter more than strength (e.g. crash or bolted-joint castings).110 MPa yield · 65 HB
- TB7Dimensionally stable, ductile condition for castings that will see elevated temperature or need stress relief before precision machining.105 MPa yield · 65 HB
- FCheapest condition for low-stress, leak-tight housings where dimensional stability after machining is not critical.85 MPa yield · 60 HB
Working with LM25-F
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.
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.
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 | — |
LM25-F — frequently asked
What is LM25-F used for?
LM25-F 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-F?
LM25-F has a typical yield strength of 85 MPa (12.3 ksi) and a tensile strength of 150 MPa (21.8 ksi) — weaker than 89% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is LM25-F easy to machine?
Reasonably — machinability is rated good (55/100, worse than 58% 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-F 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-F?
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-F 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-F?
LM25-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 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.
Can FabDigit make parts in LM25-F?
Yes — LM25-F is available for CNC machining with instant online pricing. 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.