Aluminum LM20
BS LM20
LM20 is a eutectic AlSi12 casting alloy to BS 1490, comparable to ASTM 413.0, supplied as-cast (M) in die, gravity die and sand conditions with optional Sr modification.
Reference datasheet — LM20 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 M-DC condition
LM20 tempers and conditions
LM20 is supplied in 4 conditions, soft to hard. M-DC 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 |
|---|---|---|---|---|---|---|
M | For low-volume or large sand-cast parts where the alloy's fluidity and low shrinkage matter more than strength. | 85 | 165 | 5 | 55 HB | 34 % IACS |
M | Choose for thicker-section permanent-mould parts needing weld or pressure tightness; moderate strength with slightly better ductility than sand cast. | 95 | 190 | 5 | 60 HB | 32 % IACS |
M | Specify when maximum ductility and fatigue life are needed: chemical modification refines the eutectic silicon plates into fibres. | 95 | 210 | 8 | 58 HB | 32 % IACS |
M-DCDefault M | Standard supply condition for thin-wall pressure die castings; highest strength thanks to the chilled fine eutectic skin. | 135 | 260 | 3 | 78 HB | 31 % IACS |
What is LM20?
LM20 is a eutectic AlSi12 casting alloy to BS 1490, comparable to ASTM 413.0, supplied as-cast (M) in die, gravity die and sand conditions with optional Sr modification. Its eutectic composition gives the highest fluidity and lowest shrinkage of the common casting alloys, which suits intricate 1–2 mm wall die castings at 135 MPa yield, 260 MPa tensile, 3% elongation and 78 HB. It is not heat treatable, service is limited to about 150 °C and machinability is low (35) because of the abrasive silicon; LM9/360.0 adds magnesium if heat treatment is required. LM20 has a density of 2.66 g/cm³ (0.0961 lb/in³), lighter than 84% of aluminum grades. It melts at 574°C (1,065 °F). LM20 has a yield strength of 135 MPa (19.6 ksi) and a tensile strength of 260 MPa (37.7 ksi) — weaker than 72% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
What is LM20 used for?
- Thin-wall die castings
- Housings and enclosures
- Pump and motor casings
- Intricate covers and bezels
- Automotive brackets
- Marine fittings
Limitations
- Hard to polish — 40/100, worse than 91% of aluminum grades
- Low fracture toughness — 16 MPa·√m (14.6 ksi·√in), worse than 89% of aluminum grades
- Difficult to machine — 35/100, worse than 86% of aluminum grades
- Limited formability — 10/100, worse than 80% of aluminum grades
- Limited ductility — 3%, worse than 79% of aluminum grades
LM20 properties
Typical room-temperature values for LM20-M-DC; bars are the position among aluminum grades.
Physical3
LM20 has a density of 2.66 g/cm³ (0.0961 lb/in³), lighter than 84% of aluminum grades. It melts at 574°C (1,065 °F).
Mechanical12
LM20 has a yield strength of 135 MPa (19.6 ksi) and a tensile strength of 260 MPa (37.7 ksi) — weaker than 72% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
LM20 is rated for continuous service to 150°C (302 °F). It conducts heat at 121 W/m·K (69.9 BTU/hr·ft·°F), worse than 76% of aluminum grades. Thermal expansion is 20.4 µm/m·K (11.3 µin/in·°F).
Electrical3
LM20 conducts electricity at 31 % IACS, worse than 68% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (58/100), better than 57% of aluminum grades.
Sustainability4
Producing a kilogram of LM20 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 85%.
Manufacturability8
LM20's machinability is fair (35/100, worse than 86% of aluminum grades); weldability good (55/100); 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. LM20 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with LM20
Is LM20 easy to machine?
Abrasive eutectic silicon demands PCD or polished-flute carbide tooling, high speed and low feed with flood or MQL coolant; expect short tool life with uncoated HSS.
Can LM20 be welded?
TIG/MIG with 4047 (AlSi12) filler works well on gravity and sand castings; high-pressure die castings blister from entrapped gas, so prefer vacuum die casting or mechanical joining.
Can LM20 be formed, bent or molded?
Outstanding die-casting alloy — low shrinkage, high fluidity for 1–2 mm walls, low hot-tearing; not heat treatable and not workable cold.
LM20 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 |
|---|---|---|
| Sinear-eutectic, gives the fluidity | 10 – 13 | 11.5 |
| Cu | ≤ 0.4 | 0.15 |
| Mgtoo low for heat-treat response | ≤ 0.2 | 0.05 |
| Feaids die release, forms brittle needles when high | ≤ 1 | 0.6 |
| Mn | ≤ 0.5 | 0.25 |
| Ni | ≤ 0.1 | 0.03 |
| Zn | ≤ 0.2 | 0.05 |
| Pb | ≤ 0.1 | 0.03 |
| Sn | ≤ 0.05 | 0.01 |
| Tigrain refiner residual | ≤ 0.2 | 0.05 |
| Al | balance |
What surface finishes work on LM20?
Takes chromate/phosphate conversion coatings, powder coat and paint well; decorative anodizing gives an uneven dark grey, so use hard anodize only where wear resistance rather than colour matters.
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).
Organic Coating
Equivalent designations
Standards and trade names that resolve to Aluminum LM20 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 413.0
How much does LM20 cost?
LM20 is a standard-cost aluminum ($$), 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.
LM20 — frequently asked
What is LM20 used for?
LM20 is typically used for thin-wall die castings, housings and enclosures, pump and motor casings, intricate covers and bezels, automotive brackets and marine fittings. In short: highest-fluidity casting alloy; thin walls, low shrinkage; not heat treatable.
What is the yield strength of LM20?
LM20 has a typical yield strength of 135 MPa (19.6 ksi) and a tensile strength of 260 MPa (37.7 ksi) — weaker than 72% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is LM20 easy to machine?
Not especially — machinability is rated fair (35/100, worse than 86% of aluminum grades). Abrasive eutectic silicon demands PCD or polished-flute carbide tooling, high speed and low feed with flood or MQL coolant; expect short tool life with uncoated HSS.
Can LM20 be welded?
Yes — weldability is rated good (55/100). TIG/MIG with 4047 (AlSi12) filler works well on gravity and sand castings; high-pressure die castings blister from entrapped gas, so prefer vacuum die casting or mechanical joining.
What surface finishes work on LM20?
Takes chromate/phosphate conversion coatings, powder coat and paint well; decorative anodizing gives an uneven dark grey, so use hard anodize only where wear resistance rather than colour matters.
Can LM20 be formed, bent or molded?
Outstanding die-casting alloy — low shrinkage, high fluidity for 1–2 mm walls, low hot-tearing; not heat treatable and not workable cold.
What is the maximum service temperature of LM20?
LM20 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 LM20 M-DC and LM20 M-SC?
M-DC is the default condition — standard supply condition for thin-wall pressure die castings; highest strength thanks to the chilled fine eutectic skin. M-SC: for low-volume or large sand-cast parts where the alloy's fluidity and low shrinkage matter more than strength. Yield strength is 135 MPa in M-DC versus 85 MPa in M-SC.
How much does LM20 cost?
LM20 is a standard-cost aluminum ($$), 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
- BS 1490 — Aluminium and aluminium alloy ingots and castings for general engineering purposes — BSI (1988)
- ASTM B85 / B108 — Aluminum-Alloy Die Castings and Permanent Mold Castings (413.0, A413.0) — ASTM International (2021)
- EN 1706 — Aluminium and aluminium alloys, castings (EN AC-44300 AlSi12(Cu)) — CEN (2020)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Aluminum Association Teal Sheets — Registration Record of Casting Alloys — The Aluminum Association (2015)
- (ADC12/AlSi12) (2025)
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.