LM30 Aluminium Alloy

BS 1490 · Group C · Special Purpose — Limited Application

LM30
Aluminium Alloy

Al-Si17Cu4.5Mg0.5 — High-Silicon HPDC Piston Alloy

Gravity Die Casting

Low Pressure Die Casting

High Pressure Die Casting

ISO 9001:2015

At a Glance

High-Silicon HPDC Piston Alloy

LM30 is a high-silicon (16–18%), high-copper (4–5%) Group C alloy developed specifically for HPDC pistons and high-wear components. Unlike most Group C alloys which are rated ‘n’ (not recommended) for HPDC, LM30 achieves a rating of 3 (Good) for high-pressure die casting — making it one of the very few hypereutectic alloys suitable for HPDC production.

The combination of hypereutectic Si and high Cu content gives LM30 excellent wear resistance, good as-cast hardness (120–140 HB), and reasonable HPDC castability. Only stress relief (TS) is specified beyond M condition in BS 1490.

Rated 3 (Good) for HPDC — Unique Among Group C

LM30 is rated 3 for HPDC — the only Group C piston alloy with a positive HPDC rating. This makes it the preferred specification when a high-Si wear-resistant alloy must be produced by high-pressure die casting in volume. For gravity casting of high-Si alloys, LM28 or LM29 are preferred.

LM30 Chemical Composition — BS 1490:1988

Element	Symbol	Min %	Max %	Role in alloy
Silicon	Si	16.0	18.0	16–18% Si – hypereutectic. High primary Si content delivers wear resistance and low thermal expansion.
Copper	Cu	4.0	5.0	4–5% Cu – highest Cu in Group C piston alloys. Provides significant as-cast hardness and improves HPDC castability.
Magnesium	Mg	0.4	0.7	0.4–0.7% Mg – controlled addition for some precipitation response in TS condition.
Iron	Fe	—	1.1	Up to 1.1% Fe – reflects HPDC application where higher Fe reduces die soldering.
Manganese	Mn	—	0.3	Impurity limit. Controlled to maintain clean melt.
Nickel	Ni	—	—	Impurity limit.
Zinc	Zn	—	0.2	Impurity limit. Higher Zn increases hot-cracking risk.
Lead	Pb	—	0.1	Impurity limit.
Tin	Sn	—	—	Impurity limit.
Titanium	Ti	—	0.2	Grain refiner when added as TiB₂ master alloy.
Aluminium	Al	Remainder		Base metal. Composition verified by OES (ARUN Technology UK, MERLIN-4 ULTRA).
Other elements	—	—	0.05 each / 0.15 total	Each unspecified element ≤0.05%, total ≤0.15%.

LM30 Equivalent Grades — International Standards

BS 1490

LM30

Group C · Special Purpose — Limited Application Al-Si17Cu4.5Mg0.5

EN 1706

—

ASTM / AA

B390.0

B390.0 — closest US equivalent

JIS H 5302

ADC14

Al-Si-Cu-Mg — high-Si HPDC alloy

DIN 1725-2

—

No DIN equivalent

ISO 3522

—

No ISO standard designation

LM30 Mechanical Properties — BS 1490:1988 Table 4

Minimum values from separately cast test samples per BS 1490:1988. These are guaranteed minimums — not average values. Properties in actual castings vary with section thickness, cooling rate, and local geometry.

Condition	Process	Tensile N/mm² min	0.2% Proof N/mm²	Elongation % min	Brinell HB
M	Chill / GDC	150	—	—	120–130
TS	Chill / GDC	160	—	—	120–135

LM30 Physical & Thermal Properties

Density

2.73 g/cm³

Approx. 1/3 the density of steel

Freezing Range

580–510 °C

Solidification temperature range

Thermal Conductivity

121 W/m·K

Heat dissipation capability

Electrical Conductivity

— % IACS

Relative to copper standard

Linear Expansion

19 ×10⁻⁶/K

20–300°C range

Brinell Hardness

120–140 HB

As-cast or stated condition

Property	Rating	Notes
Corrosion resistance	Fair (D)	High Cu reduces corrosion resistance significantly.
Decorative anodising	Poor (D)	Not suitable for anodising.
Weldability	Poor	Hypereutectic Si + high Cu — not weldable.
Machinability group	1 — Difficult	Group 1 — high Si demands carbide or diamond tooling.

LM30 Casting Process Suitability —BS 1490:1988 Table 8

Ratings from BS 1490:1988 Table 8. Scale: 4 = Excellent, 3 = Good, 2 = Fair, 1 = Poor, n = Not normally recommended.

Sand Casting

Gravity Die Casting (GDC)

Low Pressure (LPDC)

High Pressure (HPDC)

Castability Property	Rating	Explanation
Fluidity	3 — Good	Cu addition and HPDC process parameters compensate for high-Si castability challenges.
Resistance to hot tearing	2 — Fair	Wide freezing range due to high Cu — controlled solidification required.
Pressure tightness	2 — Fair	Moderate pressure tightness.
Machinability (as-cast)	1 — Difficult	Group 1 — high Si demands carbide or diamond tooling.

LM30 Heat Treatment — BS 1490:1988 Conditions

M

As Cast

No heat treatment. Used as-cast. Dimensional stability is the priority.

TS

Stress Relieved

200–250°C, 2–4 hours. Reduces residual casting stresses without significant property change.

TB

Solution + Natural Age

Solution treat, quench, age at room temperature. Strength develops over days to weeks.

TB7

Solution + Stabilise

Solution treat, quench, then stabilise at low temperature. Good ductility and dimensional stability.

TE

Artificially Aged Only

Age at 160–180°C, 6–12 hours. Moderate strength improvement without solution treatment.

TF

T6 — Peak Strength

Solution treat + quench + artificial age. Peak strength condition. Full in-house at Creative Alucast.

TF7

T7 — Over-aged / Stabilised

Solution treat + quench + over-age. Slightly lower strength than TF but superior dimensional stability.

M and TS Conditions Only

LM30 is available only in M (as-cast) and TS (stress relieved) conditions per BS 1490. No precipitation hardening treatment is specified. The as-cast hardness of 120–140 HB is the design-intent mechanical state — comparable to heat-treated general-purpose alloys.

Typical Applications of LM30

Industry	Typical Parts	Why LM13
Automotive	HPDC engine pistons, high-wear cylinder components	Hypereutectic wear resistance + HPDC suitability
Industrial	High-wear HPDC components, compressor pistons	Wear resistance at volume

HPDC Pistons

High-Wear Components

Compressor Pistons

Engine Components

When NOT to Specify LM30

Do not specify LM30 for general engineering — high machining cost and limited foundry availability. For gravity cast hypereutectic applications, LM28 or LM29 are preferred.

Common Questions About LM30

What is the chemical composition of LM30 aluminium alloy?

LM30 per BS 1490:1988 has nominal composition Al-Si17Cu4.5Mg0.5. Silicon: 16.0–18.0%, Copper: 4.0–5.0%, Magnesium: 0.4–0.7%. The remainder is aluminium with controlled impurity limits.

What is the EN 1706 / European equivalent of LM30?

The EN 1706 equivalent of BS 1490 LM30 is —, with chemical symbol designation —. This European standard supersedes the German DIN designation —.

What is the ASTM / AA equivalent of LM30?

The ASTM/Aluminium Association equivalent of LM30 is B390.0. B390.0 — closest US equivalent.

What is the JIS equivalent of LM30?

The JIS H 5302 equivalent of LM30 is ADC14. Al-Si-Cu-Mg — high-Si HPDC alloy.

What is the tensile strength of LM30?

The minimum tensile strength of LM30 is 160 N/mm² in the best condition and process per BS 1490:1988 Table 4 (separately cast test samples). Properties vary with casting process and heat treatment condition.

Can LM30 be heat treated to T6?

No — LM30 is not normally heat-treated to T6. Available conditions: M, TS.

What casting processes are suitable for LM30?

Per BS 1490:1988 Table 8: Sand casting (n), Gravity Die Casting (2), Low Pressure Die Casting (2), High Pressure Die Casting (3). Scale: 4=Excellent, 3=Good, 2=Fair, n=Not recommended.

What is the density of LM30 aluminium alloy?

The density of LM30 is 2.73 g/cm³ — approximately one-third the density of steel (7.85 g/cm³), making it ideal for lightweight structural applications.