Aluminum LM27
BS LM27
LM27 is an AlSi7Cu2 general-purpose casting alloy to BS 1490, comparable to ASTM 319.0, available as-cast (M) and in TE, T6 and T7 conditions.
Reference datasheet — LM27 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 condition
LM27 tempers and conditions
LM27 is supplied in 4 conditions, soft to hard. M 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 |
|---|---|---|---|---|---|---|
MDefault Thermomechanically controlled processed | Default stocked condition: general engineering sand or gravity-die castings where no heat treatment is applied. | 110 | 180 | 2 | 80 HB | 27 % IACS |
Solution heat treated and overaged (stabilized) | Use when dimensional and thermal stability at elevated service temperature matters more than peak strength (e.g. heated housings). | 155 | 225 | 3 | 80 HB | 28 % IACS |
Solution heat treated and artificially aged | Peak-strength condition (319.0-T6 practice) for highly loaded structural castings; expect some distortion/quench stress and reduced conductivity. | 180 | 255 | 2 | 92 HB | 25 % IACS |
Precipitation (artificially aged) treated from the as-cast condition | Choose when higher proof stress, hardness and dimensional stability are needed without the distortion risk of a full solution treatment. | 185 | 215 | 1 | 105 HB | 26 % IACS |
What is LM27?
LM27 is an AlSi7Cu2 general-purpose casting alloy to BS 1490, comparable to ASTM 319.0, available as-cast (M) and in TE, T6 and T7 conditions. It is a common secondary-alloy choice for automotive and general engineering castings, offering pressure-tight sections and good machinability (65) at 110 MPa yield, 180 MPa tensile, 2% elongation and 80 HB. Copper lowers corrosion resistance (42) and makes weld repair hot-crack sensitive, and thermal conductivity is only 109 W/m·K; LM25/356.0 is the alternative where corrosion resistance and weldability matter more. LM27 has a density of 2.76 g/cm³ (0.0997 lb/in³), heavier than 70% of aluminum grades. It melts at 520°C (968 °F). LM27 has a yield strength of 110 MPa (16 ksi) and a tensile strength of 180 MPa (26.1 ksi) — weaker than 81% of aluminum grades. Elongation at break is 2% and the elastic modulus is 74 GPa (10.7 Msi).
What is LM27 used for?
- Cylinder heads
- Housings and casings
- Engine blocks and crankcases
- Gearbox and pump bodies
- Manifolds
- General engineering brackets and covers
Limitations
- Hard to polish — 40/100, worse than 91% of aluminum grades
- Poor heat conductor — 109 W/m·K (63 BTU/hr·ft·°F), worse than 90% of aluminum grades
- Limited ductility — 2%, worse than 87% of aluminum grades
- Low electrical conductivity — 27 % IACS, worse than 86% of aluminum grades
- Low fracture toughness — 17 MPa·√m (15.5 ksi·√in), worse than 83% of aluminum grades
LM27 properties
Typical room-temperature values for LM27-M; bars are the position among aluminum grades.
Physical3
LM27 has a density of 2.76 g/cm³ (0.0997 lb/in³), heavier than 70% of aluminum grades. It melts at 520°C (968 °F).
Mechanical14
LM27 has a yield strength of 110 MPa (16 ksi) and a tensile strength of 180 MPa (26.1 ksi) — weaker than 81% of aluminum grades. Elongation at break is 2% and the elastic modulus is 74 GPa (10.7 Msi).
Thermal6
LM27 is rated for continuous service to 150°C (302 °F). It conducts heat at 109 W/m·K (63 BTU/hr·ft·°F), worse than 90% of aluminum grades. Thermal expansion is 21.5 µm/m·K (11.9 µin/in·°F).
Electrical3
LM27 conducts electricity at 27 % IACS, worse than 86% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (42/100), worse than 69% of aluminum grades.
Sustainability4
Producing a kilogram of LM27 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 90%.
Manufacturability7
LM27's machinability is good (65/100, better than 62% of aluminum grades); weldability fair (40/100).
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. LM27 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with LM27
Is LM27 easy to machine?
Machines well with the Cu phase breaking chips; use polycrystalline-diamond or coated carbide at high speed because primary/eutectic Si is abrasive, and flood coolant to avoid built-up edge.
Can LM27 be welded?
TIG/MIG repair welding is possible with 4043/4047 filler and preheat 150–200 °C, but the ~2 % Cu makes it hot-crack sensitive — not recommended for structural weldments.
Can LM27 be formed, bent or molded?
Excellent foundry alloy: good fluidity, low hot-tearing, pressure-tight sections; suits sand, gravity and low-pressure die casting with chills or directional solidification for thick sections.
LM27 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 – 8 | 7 |
| Cu | 1.5 – 2.5 | 2 |
| Mn | 0.2 – 0.6 | 0.4 |
| Mgmax only | ≤ 0.35 | 0.15 |
| Feimpurity max | ≤ 0.8 | 0.6 |
| Nimax only | ≤ 0.3 | |
| Znmax only | ≤ 1 | |
| Pbmax only | ≤ 0.2 | |
| Snmax only | ≤ 0.1 | |
| Tigrain refiner, max | ≤ 0.2 | 0.1 |
| Al | balance |
What surface finishes work on LM27?
Decorative anodising is poor (grey mottled); prefer chromate/chrome-free conversion coating plus primer/powder coat, or hard anodise / electroless nickel where wear resistance is needed; impregnation can be used to seal porosity.
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 LM27 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 319.0
How much does LM27 cost?
LM27 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.
LM27 — frequently asked
What is LM27 used for?
LM27 is typically used for cylinder heads, housings and casings, engine blocks and crankcases, gearbox and pump bodies, manifolds and general engineering brackets and covers. In short: low-cost general-purpose casting; good machinability, copper-bearing; lower corrosion resistance.
What is the yield strength of LM27?
LM27 has a typical yield strength of 110 MPa (16 ksi) and a tensile strength of 180 MPa (26.1 ksi) — weaker than 81% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is LM27 easy to machine?
Reasonably — machinability is rated good (65/100, better than 62% of aluminum grades). Machines well with the Cu phase breaking chips; use polycrystalline-diamond or coated carbide at high speed because primary/eutectic Si is abrasive, and flood coolant to avoid built-up edge.
Can LM27 be welded?
With care — weldability is rated fair (40/100). TIG/MIG repair welding is possible with 4043/4047 filler and preheat 150–200 °C, but the ~2 % Cu makes it hot-crack sensitive — not recommended for structural weldments.
What surface finishes work on LM27?
Decorative anodising is poor (grey mottled); prefer chromate/chrome-free conversion coating plus primer/powder coat, or hard anodise / electroless nickel where wear resistance is needed; impregnation can be used to seal porosity.
Can LM27 be formed, bent or molded?
Excellent foundry alloy: good fluidity, low hot-tearing, pressure-tight sections; suits sand, gravity and low-pressure die casting with chills or directional solidification for thick sections.
What is the maximum service temperature of LM27?
LM27 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 LM27-M and LM27-TE?
M is the default condition — default stocked condition: general engineering sand or gravity-die castings where no heat treatment is applied. TE: choose when higher proof stress, hardness and dimensional stability are needed without the distortion risk of a full solution treatment. Yield strength is 110 MPa in M versus 185 MPa in TE.
How much does LM27 cost?
LM27 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)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (319.0 data) — ASM International (1990)
- Aluminum Association Teal Sheets — Registration Record of Casting Alloys — The Aluminum Association (2015)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- ASTM B26/B26M & B108 — Aluminum-Alloy Sand and Permanent Mold Castings — ASTM (2022)
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.