Aluminum LM20 M-GDC
Finish state
BS LM20
Choose for thicker-section permanent-mould parts needing weld or pressure tightness; moderate strength with slightly better ductility than sand cast.
Values for the M-GDC condition
Other LM20 tempers and conditions
LM20 is listed in 4 conditions; see the grade overview at LM20.
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-GDCThis page 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 M-GDC?
LM20 M-GDC is LM20 supplied in the M-GDC condition — choose for thicker-section permanent-mould parts needing weld or pressure tightness; moderate strength with slightly better ductility than sand cast. LM20 M-GDC has a yield strength of 95 MPa (13.8 ksi) and a tensile strength of 190 MPa (27.6 ksi) — weaker than 86% of aluminum grades. Elongation at break is 5% and the elastic modulus is 71 GPa (10.3 Msi). LM20 M-GDC 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). M-DC is the default condition FabDigit quotes; M-GDC is available on request or by drawing note.
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
- Low strength — 95 MPa (13.8 ksi), worse than 86% of aluminum grades
- Difficult to machine — 38/100, worse than 84% of aluminum grades
- Limited formability — 10/100, worse than 80% of aluminum grades
LM20 M-GDC properties
Typical room-temperature values for LM20 M-GDC; 10 are specific to this condition. Other listed values are LM20 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
LM20 M-GDC 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 M-GDC has a yield strength of 95 MPa (13.8 ksi) and a tensile strength of 190 MPa (27.6 ksi) — weaker than 86% of aluminum grades. Elongation at break is 5% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
LM20 M-GDC is rated for continuous service to 150°C (302 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 20.4 µm/m·K (11.3 µin/in·°F).
Electrical3
LM20 M-GDC conducts electricity at 32 % IACS, worse than 63% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (58/100), better than 57% of aluminum grades.
Sustainability4
Producing a kilogram of LM20 M-GDC 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 M-GDC's machinability is fair (38/100, worse than 84% of aluminum grades); weldability very good (75/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with LM20 M-GDC
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.
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.
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 | — |
LM20 M-GDC — frequently asked
What is LM20 M-GDC used for?
LM20 M-GDC 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 M-GDC?
LM20 M-GDC has a typical yield strength of 95 MPa (13.8 ksi) and a tensile strength of 190 MPa (27.6 ksi) — weaker than 86% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is LM20 M-GDC easy to machine?
Not especially — machinability is rated fair (38/100, worse than 84% 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 M-GDC be welded?
Yes — weldability is rated very good (75/100). 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 M-GDC?
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 M-GDC 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 M-GDC?
LM20 M-GDC 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.