Nov 13 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Heat Treatment
Forging
Hot Working
Cold working
Annealing
Aging
Hardening
Applications
Introduction
Aluminium / Aluminum alloys have high ductility and corrosion resistance. At subzero temperatures, their strength can be increased. However, their strength can be reduced at high temperatures of about 200-250°C. Aluminium / Aluminum 2618 alloy is an age hardenable alloy containing magnesium and copper.
The datasheet given below gives details about Aluminium / Aluminum 2618 alloy.
Chemical Composition
The following table shows the chemical composition of Aluminium / Aluminum 2618 alloy.
|
Element
|
Composition
|
|
Copper
|
1.9 - 2.7
|
|
Silicon
|
0.25
|
|
Iron
|
0.9 - 1.3
|
|
Magnesium
|
1.3 -1.8
|
|
Titanium
|
0.04 - 0.1
|
|
Nickel
|
0.9 - 1.2
|
|
Others
|
0.05
|
|
Aluminum
|
92 - 94
|
Physical Properties
The physical properties of the Aluminium / Aluminum 2618 alloy are tabulated below.
|
Property
|
Metric
|
Imperial
|
|
Density
|
2.76 g/cc
|
0.0997 lb/in^3
|
|
Melting Point
|
549 - 638 °C
|
1020 - 1180 °F
|
Mechanical Properties
The mechanical properties of the Aluminium / Aluminum 2618 alloy are outlined in the following table.
|
Properties
|
Metric
|
Tensile
|
|
|
Tensile Strength
|
372 MPa
|
54000 psi
|
|
|
Tensile Strength, Ultimate
|
441 Mpa
|
64000 psi
|
|
|
Shear Strength
|
262 Mpa
|
38000 psi
|
|
|
Fatigue Strength (completely reversed stress; RR Moore machine/specimen)
|
124 Mpa
|
18000 psi
|
|
| |
| |
|
Elastic Modulus (AA; Typical; Average of tension and compression)
|
74.5 Gpa
|
10800 ksi
|
|
| |
|
Poisson's ratio
|
0.33
|
0.33
|
|
|
Elongation at Break
|
10% at -28.0 °C
|
10% -18.4 °F
|
|
|
14% at 149 °C
|
14% at 300 °F
|
|
|
50% at 260 °C
|
50% at 500 °F
|
|
Thermal Properties
The thermal properties of the Aluminium / Aluminum 2618 alloy are given in the following table.
|
Thermal Properties
|
Metric
|
Imperial
|
|
Thermal Conductivity
|
146 W/m-K
|
1010 BTU-in/hr-ft²-°F
|
|
Specific Heat Capacity
|
0.875 J/g-°C
|
0.209 BTU/lb-°F
|
Other Designations
Other designations equivalent to the Aluminium / Aluminum 2618 alloy include DIN 3.1924.
Fabrication and Heat Treatment
Machinability
Aluminium / Aluminum 2618 alloy has good machining characteristics. It can be smoothly machined in heat treated conditions.
Forming
Aluminium / Aluminum 2618 alloy has good hot and cold formability.
Welding
Aluminium / Aluminum 2618 alloy can be welded using resistance welding techniques. It is not welded using conventional fusion welding methods because the heat produced by these methods can be harmful to this alloy.
Heat Treatment
Aluminium / Aluminum 2618 alloy can be heat treated at 530°C (985°F) for a sufficient period of time followed by quenching in water.
Forging
Aluminium / Aluminum 2618 alloy is forged at 372 to 522°C (700 to 970°F).
Hot Working
Aluminium / Aluminum 2618 alloy is hot worked at 350 to 372°C (660 to 700°F).
Cold working
Aluminium / Aluminum 2618 alloy can be cold worked in the heat treated or annealed conditions.
Annealing
Annealing of Aluminium / Aluminum 2618 alloy can be performed at 385°C (725°F) for 4 h. It can be then slowly cooled in the furnace.
Aging
Aluminium / Aluminum 2618 alloy can be aged at 527°C (980°F) for 24 h followed by quenching in boiling water. Aging process can be again repeated at 199°C (390°F) for 20 h followed by cooling in air.
Hardening
Aluminium / Aluminum 2618 alloy can be hardened by cold working and aging.
Applications
Aluminium / Aluminum 2618 alloy is mainly used in manufacturing aircraft engines.