Closed-die forgings
Near-net-shape parts such as pistons, impeller blanks and brackets, forged to your drawing with controlled grain flow.
Heat-resistant forgings
2618 / 2618A Aerospace Aluminium Forgings
2618 and 2618A are aluminium-copper-magnesium alloys with iron and nickel added so that forgings keep their strength at 150 – 250 °C. They are the standard choice for pistons, compressor impellers and hot-running airframe parts. Metline supplies 2618-T61 die and hand forgings, rings and forging stock to AMS 4132, ASTM B247 and European specifications, shipped worldwide.
- Alloy
- 2618 / 2618A (Al-Cu-Mg-Fe-Ni)
- Main temper
- T61 (also T6, T652)
- Specifications
- AMS 4132 · ASTM B247
- Service limit
- Up to ~250 °C
What makes 2618 a forging alloy for hot parts
Most strong aluminium alloys lose their strength quickly above 120 – 150 °C because their fine precipitates coarsen. 2618 adds about 1 % iron and 1 % nickel, which combine into hard, thermally stable intermetallic particles (Al9FeNi) that do not dissolve or coarsen at service temperature. They pin the structure and give 2618 its creep resistance.
The alloy grew out of the British "RR58" (Hiduminium) family developed for aero-engine parts, and its best-known use was the airframe of the Concorde, which ran warm from aerodynamic heating during supersonic cruise. Today forged 2618 is used for aircraft and racing pistons, centrifugal compressor impellers, turbocharger compressor wheels, and fittings and brackets that sit close to engines.
Forging suits 2618 well. Closed-die forging aligns the grain flow with the part contour, which improves fatigue and toughness in impellers and pistons, and the alloy forges readily between about 400 and 450 °C. After forging, parts are solution treated, quenched (often in hot or boiling water to limit distortion in the T61 condition) and artificially aged.
2618 and 2618A chemical composition (wt %)
Values are the registered limits for each alloy. Some data sheets print a 6061-style composition for 2618A with no nickel; that is simply wrong, because nickel is what defines the alloy.
| Element | 2618 (AA / ASTM) | 2618A (EN AW-2618A) | Role |
|---|---|---|---|
| Copper (Cu) | 1.9 – 2.7 | 1.8 – 2.7 | Precipitation strengthening with Mg |
| Magnesium (Mg) | 1.3 – 1.8 | 1.2 – 1.8 | Forms the S-phase (Al2CuMg) with copper |
| Iron (Fe) | 0.9 – 1.3 | 0.9 – 1.4 | With Ni forms heat-stable Al9FeNi particles |
| Nickel (Ni) | 0.9 – 1.2 | 0.8 – 1.4 | Elevated-temperature and creep strength |
| Silicon (Si) | 0.10 – 0.25 | 0.15 – 0.25 | Controlled addition |
| Titanium (Ti) | 0.04 – 0.10 | 0.20 max (Ti + Zr 0.25 max) | Grain refiner |
| Manganese (Mn) | — | 0.25 max | Impurity |
| Zinc (Zn) | 0.10 max | 0.15 max | Impurity |
| Others each / total | 0.05 / 0.15 | 0.05 / 0.15 | |
| Aluminium | Remainder | Remainder |
Mechanical and physical properties of 2618 forgings
Typical room-temperature properties for 2618-T61 are about 440 MPa tensile strength, 370 MPa yield strength, 10 % elongation and 115 HB hardness. Specified minimums in AMS 4132 and ASTM B247 are lower and depend on forging type, thickness and test direction, with short-transverse values the lowest. Design to the minimums printed on the certificate, not to typical values.
| Property (2618-T61) | Typical value |
|---|---|
| Tensile strength | 440 MPa / 64 ksi |
| Yield strength (0.2 %) | 370 MPa / 54 ksi |
| Elongation | 10 % |
| Shear strength | 260 MPa / 38 ksi |
| Fatigue strength (5×10⁸ cycles, R.R. Moore) | 125 MPa / 18 ksi |
| Brinell hardness | 115 HB |
The real advantage of 2618 appears at temperature. The table below shows how much strength forgings keep after long exposure:
| Test temperature | Tensile strength | Yield strength | Elongation |
|---|---|---|---|
| 24 °C | 440 MPa | 370 MPa | 10 % |
| 100 °C | 420 MPa | 350 MPa | 10 % |
| 150 °C | 345 MPa | 305 MPa | 14 % |
| 205 °C | 220 MPa | 180 MPa | 24 % |
| 260 °C | 90 MPa | 62 MPa | 50 % |
Typical values for 2618-T61 after 10,000 hours at the test temperature (ASM data). They show strength retention, not design minimums.
Physical properties (T61)
- Density
- 2.76 g/cm³ (0.0999 lb/in³)
- Melting range
- about 549 – 638 °C
- Modulus of elasticity
- about 74.5 GPa (10,800 ksi)
- Thermal conductivity
- about 145 – 150 W/m·K
- Coefficient of thermal expansion
- about 22.3 µm/m·°C (20 – 100 °C)
- Electrical conductivity
- about 37 % IACS
Forging specifications and equivalents
| Specification | Product | Notes |
|---|---|---|
| SAE AMS 4132 | 2618-T61 die and hand forgings | Main US aerospace forging specification |
| ASTM B247 | Die, hand and rolled-ring forgings | Includes 2618-T61 alongside 2014, 2219, 6061, 7075 |
| UK DTD 717A, 731B, 745A | 2618A forging stock and forgings | Legacy British aerospace specifications still quoted on older drawings |
| EN AW-2618A (AlCu2Mg1.5Ni) | European designation | Composition per EN 573-3; Werkstoff 3.1924 |
| UNS A92618 | US unified number | — |
| China | 2A70 is the close counterpart | GB/T 3190; see our 2A70 page |
Many engine and airframe programmes also call for ultrasonic inspection to AMS-STD-2154 or ASTM B594, macro-etch grain-flow checks on a first-article forging, and electrical conductivity or hardness checks to confirm heat treatment.
2618 forging types we supply
Open-die (hand) forgings
Blocks, pancakes and stepped shapes for machining when die tooling is not justified.
Discs and pancakes
Upset-forged blanks for compressor impellers and wheels, ultrasonically inspected.
Rolled rings
Seamless rings for casings, flanges and engine-mount rings.
Forging stock
Extruded or cast-and-homogenised billet for customers who forge in-house.
Forged bar
Round and square forged bar for heavy machined parts.
Forgings are produced through qualified forging partners and supplied with a drawing-specific inspection plan. Maximum size depends on the forging route and the heat-treatment equipment, so we confirm feasibility against each drawing.
Machining, joining and finishing 2618 forgings
Machining
Machines well in T61, with short chips and good surface finish. The hard Fe-Ni particles increase tool wear slightly, so carbide or PCD tooling is preferred for long runs.
Welding
Fusion welding is not recommended for structural joints: 2618 is crack-sensitive and loses its heat treatment at the weld. Join with fasteners, or use friction or electron-beam processes only under qualification.
Heat treatment
Solution treatment around 525 – 535 °C, quench, then age around 190 – 200 °C for T61. T652 adds compressive stress relief after quenching.
Surface protection
Anodising or conversion coating plus paint is normal; bare 2618 has only moderate corrosion resistance.
Pistons
Racing and aero pistons are forged, machined and often hard-anodised in the ring groove or coated on the skirt.
Dimensional stability
Hot-water quenching (T61) reduces residual stress and machining distortion compared with cold-water quenching.
2618 compared with 4032, 2219 and 2014 forgings
| Factor | 2618-T61 | 4032-T6 | 2219-T6 | 2014-T6 |
|---|---|---|---|---|
| Room-temperature strength | High | Medium–high | Medium–high | High |
| Strength at 200 – 250 °C | Very good | Good | Good | Fair |
| Thermal expansion | Normal (≈ 22 µm/m·°C) | Low (≈ 19) | Normal | Normal |
| Toughness / ductility in pistons | Higher | Lower | High | Medium |
| Weldability | Poor | Poor | Good | Limited |
| Typical use | Pistons, impellers, hot fittings | Pistons with tight clearances | Welded hot structures | General high-strength forgings |
In pistons, the choice is usually between 2618 and 4032: 4032 expands less, so it can run tighter clearances and is quieter, while 2618 is tougher and tolerates detonation and high boost better. For impellers and hot fittings, 2618 is the default.
How to order 2618 forgings
- Drawing and specificationForging or finished-part drawing, alloy (2618 or 2618A), temper and specification with revision.
- Inspection requirementsUltrasonic class, grain-flow, test-coupon location and any first-article approval.
- QuotationWe confirm feasibility, tooling (for die forgings), certification and delivery terms (EXW, FOB, CIF or DAP).
- DocumentationEN 10204 3.1 certificate with chemistry, mechanical results and heat-treat traceability.
- PackingForgings are protected against corrosion and packed in wooden cases for export.
References and standards
- SAE AMS 4132 – Aluminum Alloy Die and Hand Forgings, 2618-T61
- ASTM B247 – Aluminum and Aluminum-Alloy Die Forgings, Hand Forgings, and Rolled Ring Forgings
- EN 573-3 – Chemical composition and form of wrought products
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
- ASM Handbook, Vol. 2 – Properties of Wrought Aluminum Alloys: 2618
2618 aluminium (aluminum) forgings: FAQ
Why is 2618 used for pistons?
It keeps strength and fatigue resistance at piston operating temperatures, conducts heat well and is tougher than the high-silicon 4032 alternative, so it tolerates detonation and high cylinder pressures in performance and aero engines.
Are 2618 and 2618A the same alloy?
They are close variants. 2618 is the US registration and 2618A the European one; 2618A allows slightly wider iron, nickel and titanium ranges. Mechanical properties are similar, and many programmes accept either, but the specification on your drawing decides which is certified.
What does T61 mean for 2618 forgings?
Solution heat-treated, quenched in hot or boiling water to limit residual stress, then artificially aged. It is the standard temper in AMS 4132 and ASTM B247 for 2618 forgings.
Can 2618 forgings be welded?
Fusion welding is not recommended for load-bearing joints because the alloy is crack-sensitive and loses its heat treatment. Mechanical fastening is normal.
What is the maximum service temperature of 2618?
It is generally used up to about 250 °C for long-term service. Strength falls steadily above 200 °C, so check the elevated-temperature data for the expected exposure time.
Do you supply 2618 forgings worldwide?
Yes. Metline supplies 2618 and 2618A forgings internationally with EN 10204 3.1 certificates, inspection reports and export packing.
Sourcing 2618 forgings for hot-running parts?
Send your drawing, specification and quantity. We will confirm feasibility, inspection and a delivered price.
