LM6 is an aluminium casting alloy with about 10–13% silicon. It flows into thin, complex moulds better than almost any other aluminium alloy and resists corrosion well, so it is used for thin-walled, intricate and marine castings. It is not heat treatable and machines less freely.
Quick facts
- Type
- Aluminium-silicon casting alloy (near eutectic)
- Silicon
- About 10–13%
- Castability
- Excellent: thin walls, complex shapes, pressure tight
- Tensile strength
- About 160–190 MPa in sand or chill castings
- Corrosion resistance
- Very good, including marine
- Heat treatment
- Not heat treatable
Equivalent grades
| Standard | Grade |
|---|---|
| BS 1490 | LM6 |
| EN 1706 | AC-44100 (AlSi12) |
| AA / ASTM | A413 (close) |
Equivalents are close, not identical. Name the grade and standard on the drawing.
LM6, LM25 or LM24?
| Alloy | Strength | Best for |
|---|---|---|
| LM6 | Medium | Thin, intricate, marine and pressure-tight castings |
| LM25 | Higher after heat treatment | Structural gravity and sand castings |
| LM24 / ADC12 | Medium | Pressure die castings |
Typical uses
- Thin-walled housings and covers
- Pump bodies and marine fittings
- Manifolds and pressure-tight parts
- Decorative and architectural castings
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Materials
Questions
- Can LM6 be anodised?
- Only with a poor, dark grey and patchy finish, because of its high silicon. Paint or powder coating suits it better.
- Can LM6 be heat treated?
- No. For heat-treated castings, LM25 is the usual choice.
- Is LM6 easy to machine?
- It machines fairly well, but the silicon is abrasive, so carbide or diamond-tipped tools last longer.
The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 9 October 2026.