2618 Aluminum

Representative aluminum raw/semi-finished material photo; exact grade not verified

2618 Aluminum (AA 2618) is a wrought Al–Cu–Mg alloy engineered for forgings and other products that must retain useful strength at elevated temperature. Its deliberately high iron and nickel contents form stable intermetallic dispersoids, helping the alloy resist creep and softening better than many conventional high-strength aluminum alloys. It is widely associated with forged pistons, turbocharger components, and aerospace engine hardware. Compared with 2618A, 2618 is a distinct registered Aluminum Association designation with its own specified composition limits, notably no specified manganese addition.

Chemical Composition (wt.%)
Chemical Composition wt.%
Element	Min	Max
Silicon	0.10	0.25
Iron	0.90	1.30
Copper	1.90	2.70
Magnesium	1.30	1.80
Nickel	0.90	1.20
Zinc	—	0.10
Titanium	0.04	0.10
Other elements, each	—	0.05
Other elements, total	—	0.15
Aluminum	Remainder

Composition notes

Iron: Intentional iron addition used with nickel for elevated-temperature stability.
Nickel: Intentional nickel addition used with iron for elevated-temperature stability.

Registered wrought composition limits are percent by weight for AA 2618. Aluminum is the remainder. “Others” limits apply to unspecified elements; no separate manganese or chromium limit is listed for 2618 in the registered composition row.

Values below are reported nominal or typical values for 2618, principally in the T61 condition where identified. Mechanical properties vary with product form, section thickness, heat treatment, and test direction; certified design values must come from the applicable product specification and mill test report.

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Table of 2618 Aluminum Properties

Table of 2618 Aluminum Properties
Physical Properties	Metric
Density	2.76 g/cm³2.76 g/cm³
Mechanical Properties	Metric
Tensile Strength (T61)	440 MPa
Yield Strength (T61)	372 MPa
Elongation at Break (T61)	10 %
Elastic Modulus	74.5 GPa
Thermal Properties	Metric
Melting Temperature	549 °C
Thermal Conductivity	146 W/m·K
Coefficient of Thermal Expansion	22.3 µm/m·K
Electrical Properties	Metric
Electrical Conductivity	37 % IACS

Test conditions & data notes

Density: Calculated nominal density for active wrought alloy designation 2618.
Tensile Strength (T61): Typical room-temperature value reported for T61 temper.
Yield Strength (T61): Typical room-temperature value reported for T61 temper.
Elongation at Break (T61): Typical room-temperature value reported for T61 temper.
Elastic Modulus: Typical room-temperature value.
Melting Temperature: Nominal value reported for 2618; not a specified solidus/liquidus range.
Thermal Conductivity: Typical value reported for 2618.
Coefficient of Thermal Expansion: Typical value reported for 2618.
Electrical Conductivity: Typical value reported for 2618.

Material Conditions & Tempers

2618 is supplied in annealed and heat-treated conditions. T61 is an underaged, solution-heat-treated and artificially aged condition commonly selected for elevated-temperature forged parts. Temper availability and guaranteed minimum properties depend on the applicable bar, forging, plate, or extrusion specification.

Condition	Tensile Strength	Yield / Proof Strength	Notes
O	215 MPa	125 MPa	Annealed condition for maximum ductility, forming, straightening, or machining before subsequent heat treatment. Typical values reported for 2618.
T6	440 MPa	370 MPa	Solution heat-treated and artificially aged condition for general high-strength wrought products. Typical values reported for 2618.
T61	440 MPa	372 MPa	Solution heat-treated and artificially underaged condition, commonly used for pistons and elevated-temperature forgings. Typical values reported for 2618.
T651	440 MPa	375 MPa	Solution heat-treated, artificially aged, and stress relieved by stretching; useful where reduced machining distortion is important. Typical values reported for 2618.
T6511	450 MPa	385 MPa	Stress-relieved and straightened heat-treated condition associated with extruded bar or profiles. Typical values reported for 2618.
T852	455 MPa	400 MPa	Solution heat-treated condition stress relieved by compression, used particularly for forgings requiring improved dimensional stability. Typical values reported for 2618.

Advantages & Limitations

Advantages	Limitations
Iron–nickel-containing dispersoids give 2618 better resistance to creep and strength loss at elevated temperature than many general-purpose wrought aluminum alloys. The Al–Cu–Mg matrix responds strongly to solution treatment and artificial aging, providing high room-temperature strength in T6-family tempers. Its combination of heat resistance, low density, and forgeability suits cyclically loaded engine and aerospace components. Machinability in aged conditions is generally good, making the alloy practical for complex forged-and-machined parts. Stress-relieved tempers such as T651 and T852 can help limit movement during extensive machining.	Corrosion resistance is relatively poor for an aluminum alloy; exposed components generally need an appropriate coating, conversion treatment, anodizing system, or controlled service environment. Fusion welding is generally avoided because of hot-cracking susceptibility and loss of heat-treatment strength in the heat-affected zone. Cold formability is limited in aged tempers; demanding forming should be performed in a soft condition or by hot working. Hard iron–nickel intermetallic particles can increase cutting-tool wear compared with common 6xxx-series alloys. Elevated-temperature capability does not eliminate the need for component-specific creep, fatigue, and thermal-cycle validation.

Advantages

Limitations

Iron–nickel-containing dispersoids give 2618 better resistance to creep and strength loss at elevated temperature than many general-purpose wrought aluminum alloys.
The Al–Cu–Mg matrix responds strongly to solution treatment and artificial aging, providing high room-temperature strength in T6-family tempers.
Its combination of heat resistance, low density, and forgeability suits cyclically loaded engine and aerospace components.
Machinability in aged conditions is generally good, making the alloy practical for complex forged-and-machined parts.
Stress-relieved tempers such as T651 and T852 can help limit movement during extensive machining.

Corrosion resistance is relatively poor for an aluminum alloy; exposed components generally need an appropriate coating, conversion treatment, anodizing system, or controlled service environment.
Fusion welding is generally avoided because of hot-cracking susceptibility and loss of heat-treatment strength in the heat-affected zone.
Cold formability is limited in aged tempers; demanding forming should be performed in a soft condition or by hot working.
Hard iron–nickel intermetallic particles can increase cutting-tool wear compared with common 6xxx-series alloys.
Elevated-temperature capability does not eliminate the need for component-specific creep, fatigue, and thermal-cycle validation.

Processing & Fabrication

Process	Description
Forging and extrusion	2618 is commonly hot forged or extruded. A reported hot-working range is 400–450 °C; establish the production window, soak practice, and deformation schedule through the applicable process specification.
Heat treatment	T6-family conditions are produced by solution heat treatment, quenching, and artificial aging. T61 is an intentionally underaged variant selected where the elevated-temperature balance is important.
Machining	Aged 2618 machines well with sharp polished-carbide or PCD tooling, suitable coolant, and attention to tool wear caused by hard Fe–Ni-bearing particles. Stress-relieved stock is advantageous for heavily machined parts.
Joining	Do not assume conventional fusion welding is suitable. Mechanical fastening, friction-based joining, or a qualified welding procedure with post-weld heat-treatment considerations may be preferable.
Surface protection	Specify a corrosion-protection system for service exposure. Conversion coating plus primer or a qualified anodizing/coating system may be used according to the component environment and dimensional requirements.

Applications

2618 is chosen where a lightweight wrought component sees sustained heat, thermal cycling, or high inertial loading. Its defining application space is forged, machined hardware rather than thin, corrosion-exposed sheet structures.

Forged internal-combustion-engine pistons: The alloy’s Fe–Ni dispersoids and heat-treated Al–Cu–Mg matrix support retention of useful strength during repeated elevated-temperature engine service.
Turbocharger compressor wheels and related rotating components: Low density helps reduce rotating mass while the alloy offers a useful strength and temperature-resistance combination for forged, machined parts.
Aero-engine accessory and structural forgings: 2618 combines high heat-treated strength with better elevated-temperature stability than many conventional high-strength aluminum forgings.
High-temperature aerospace hardware: The alloy is appropriate for qualified forged or machined components where thermal exposure, weight, and fatigue-aware design govern material selection.
Motorsport and performance-engine components: Forged 2618 is widely selected for pistons and similar parts that require ductility and heat tolerance under severe combustion and thermal-cycle conditions.

Standards & Designations

Designation	Value	Description
Aluminum Association	AA 2618	Registered wrought aluminum alloy designation; chemical composition limits are listed in the Aluminum Association Teal Sheets.
UNS	UNS A92618	Common Unified Numbering System designation associated with aluminum alloy 2618.
European designation	EN AW-2618	Common European designation cited for 2618; verify the required product standard and temper before claiming equivalence.

Frequently Asked Questions

How does 2618 differ from 2618A aluminum?

They are separate registered alloy designations and should not be substituted automatically. AA 2618 specifies no manganese addition and limits titanium to 0.04–0.10%, while 2618A has separately registered limits including manganese and a zirconium-plus-titanium restriction. Confirm the exact drawing, specification, and certification requirement.

Why is 2618 commonly used for forged pistons?

Its copper and magnesium enable high heat-treated strength, while intentional iron and nickel additions form stable dispersoids that improve resistance to creep and softening during elevated-temperature engine duty. Forged product and the selected temper are both important to piston performance.

Can 2618 aluminum be welded?

Conventional fusion welding is generally not preferred for critical 2618 parts because weld cracking and heat-affected-zone softening can compromise performance. Mechanical fasteners, friction-based joining, or a specifically qualified welding and post-weld treatment procedure should be considered instead.

References & Data Notes

(n.d.). Aluminum Association — International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys, December 2025. https://www.aluminum.org/sites/default/files/2026-01/Teal%20Sheets%20December%202025.pdf
(n.d.). FabDigit — Aluminum 2618: Properties, Tempers (O, T651, T61) & Uses. https://www.fabdigit.com/materials/aluminum-2618
(n.d.). MakeItFrom.com — 2618 (2618-T61, 3.1924) Aluminum. https://www.makeitfrom.com/material-properties/2618-2618-T61-3.1924-Aluminum

Composition limits and nominal density are taken from the Aluminum Association registered wrought-alloy publication. Other listed physical and temper-property values are typical reference data, not specification minimums. 2618 is not interchangeable with 2618A; obtain certified product-form and temper data for procurement or design release.