Aluminiums

Aluminium alloys are alloys in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon and zinc. There are two principal classifications, namely casting alloys and wrought alloys, both of which are further subdivided into the categories heat-treatable and non-heat-treatable. About 85% of aluminium is used for wrought products, for example rolled plate, foils and extrusions. Cast aluminium alloys yield cost-effective products due to the low melting point, although they generally have lower tensile strengths than wrought alloys. The most important cast aluminium alloy system is Al-Si, where the high levels of silicon (4.0–13%) contribute to give good casting characteristics. Aluminium alloys are widely used in engineering structures and components where light weight or corrosion resistance is require.

Alloys composed mostly of aluminium have been very important in aerospace manufacturing since the introduction of metal skinned aircraft. Aluminium-magnesium alloys are both lighter than other aluminium alloys and much less flammable than alloys that contain a very high percentage of magnesium.

Aluminium alloy surfaces will keep their apparent shine in a dry environment due to the formation of a clear, protective layer of aluminium oxide. In a wet environment, galvanic corrosion can occur when an aluminium alloy is placed in electrical contact with other metals with more negative corrosion potentials than aluminium.

Alloy designations

Wrought and cast aluminium alloys use different identification systems. Wrought aluminium is identified with a four digit number which identifies the alloying elements.

Cast aluminium alloys use a four to five digit number with a decimal point. The digit in the hundreds place indicates the alloying elements, while the digit after the decimal point indicates the form (cast shape or ingot).

Temper designation

The temper designation follows the cast or wrought designation number with a dash, a letter, and potentially a one to three digit number, e.g. 6061-T6. The definitions for the tempers are:

-F         As fabricated
-H        Strain hardened (cold worked) with or without thermal treatment
-H1      Strain hardened without thermal treatment
-H2      Strain hardened and partially annealed
-H3      Strain hardened and stabilized by low temperature heating
Second digit 
A second digit denotes the degree of hardness
-HX2 = 1/4 hard
-HX4 = 1/2 hard
-HX6 = 3/4 hard
-HX8 = full hard
-HX9 = extra hard
-O       Full soft (annealed)
-T       Heat treated to produce stable tempers
-T1     Cooled from hot working and naturally aged (at room temperature)
-T2     Cooled from hot working, cold-worked, and naturally aged
-T3     Solution heat treated and cold worked
-T4     Solution heat treated and naturally aged
-T5     Cooled from hot working and artificially aged (at elevated temperature)
-T51   Stress relieved by stretching
-T510 No further straightening after stretching
-T511 Minor straightening after stretching
-T52   Stress relieved by thermal treatment
-T6     Solution heat treated and artificially aged
-T7     Solution heat treated and stabilized
-T8     Solution heat treated, cold worked, and artificially aged
-T9     Solution heat treated, artificially aged, and cold worked
-T10   Cooled from hot working, cold-worked, and artificially aged
-W      Solution heat treated only.

Note: -W is a relatively soft intermediary designation that applies after heat treat and before aging is completed. The -W condition can be extended at extremely low temperatures but not indefinitely and depending on the material will typically last no longer than 15 minutes at ambient temperatures.

Wrought alloys

The International Alloy Designation System is the most widely accepted naming scheme for wrought alloys. Each alloy is given a four-digit number, where the first digit indicates the major alloying elements.

  • 1000 series are essentially pure aluminium with a minimum 99% aluminium content by weight and can be work hardened.
  • 2000 series are alloyed with copper, can be precipitation hardened to strengths comparable to steel. Formerly referred to as duralium, they were once the most common aerospace alloys, but were susceptible to stress corrosion cracking and are increasingly replaced by 7000 series in new designs.
  • 3000 series are alloyed with manganese, and can be work hardened.
  • 4000 series are alloyed with silicon. They are also known as silumin.
  • 5000 series are alloyed with magnesium.
  • 6000 series are alloyed with magnesium and silicon, are easy to machine, and can be precipitation hardened, but not to the high strengths that 2000 and 7000 can reach.
  • 7000 series are alloyed with zinc, and can be precipitation hardened to the highest strengths of any aluminium alloy.
  • 8000 series is a category mainly used for lithium alloys.

 

Mechanical properties of selected aluminium alloys.

Alloy

Temper

Proof Stress 0.2% (MPa)

Tensile Strength (MPa)

Shear Strength (MPa)

Elongation A5 (%)

Hardness Vickers (HV)

AA1050A

H12

H14

H16

H18

0

85

105

120

140

35

100

115

130

150

80

60

70

80

85

50

12

10

7

6

42

30

36

-

44

20

AA2011

T3

T6

290

300

365

395

220

235

15

12

100

115

AA3103

H14

0

140

45

155

105

90

70

9

29

46

29

AA4015

0

H12

H14

H16

H18

45

110

135

155

180

110-150

135-175

160-200

185-225

210-250

-

-

-

-

-

20

4

3

2

2

30-40

45-55

-

-

-

AA5083

H32

0/H111

240

145

330

300

185

175

17

23

95

75

AA5251

H22

H24

H26

0

165

190

215

80

210

230

255

180

125

135

145

115

14

13

9

26

65

70

75

46

AA5754

H22

H24

H26

0

185

215

245

100

245

270

290

215

150

160

170

140

15

14

10

25

75

80

85

55

AA6063

0

T4

T6

50

90

210

100

160

245

70

11

150

27

21

14

85

50

80

AA6082

0

T4

T6

60

170

310

130

260

340

85

170

210

27

19

11

35

75

100

AA6262

T6

T9

240

330

290

360

-

-

8

3

-

-

AA7075

0

T6

105-145

435-505

225-275

510-570

150

350

9

5

65

160

 

Formability, Machinability and Weldability

Legend: ••••• = Excellent   |  •••• = Very Good  |  ••• = Good  |  •• = Fair  |  • = Poor

B.S & Intnl Specs   Former B.S Specs Forming Machining Inert Gas Shielded Arc Spot, Seam Resistance Colour & Protective Bright Hard Plating Vitreous Enamel
1050A 0 S1B ••••• •• •••• •••• •••• ••••   •••• •••
  H8   •• ••• •••• •••• •••• ••••   •••• •••
1080A 0 S1A ••••• • •••• •••• ••••• ••••      
  H8   •• •• •••• •••• ••••• ••••      
1200 0 S1C ••••• •• •••• •••• •••• •••   •••• •••
  H4   •••• •• •••• •••• •••• •••   •••• •••
  H8   •• ••• •••• •••• •••• •••   •••• •••
1350   P1E •••••   ••••• ••••• ••••• ••••• •••••    
2014A TB HS15 ••• •••   ••••• ••     ••••  
  TF   •• ••••   ••••• ••     ••••  
2024 TB   ••• •••   •••• ••     ••••  
  TD   ••• ••••   •••• ••     ••••  
3003     ••••   •••• •••• •••        
3103 0 NS3 ••••• •• •••• ••••• •••• •   ••• ••••
  H4   •••• •• •••• ••••• •••• •   ••• ••••
  H8   •• ••• •••• ••••• •••• •   ••• ••••
5005 0 NS41 •••• •• ••••• ••••• ••••• •••••      
  H4   ••• ••• ••••• ••••• ••••• •••••      
  H8   •• ••• ••••• ••••• ••••• •••••      
5052 0   •••• •• •••• •••• ••••• ••••• •••••    
5083 0 NS8 ••• ••• ••••• ••••• •••• •••      
  H2   •• •••• ••••• ••••• •••• •••      
  H4   •• •••• ••••• ••••• •••• •••      
5086 0   ••• •• ••• ••• •••• •••• ••••    
5154A 0 NS5 •••• ••• ••••• ••••• •••• •••      
  H2   ••• •••• ••••• ••••• •••• •••      
  H4   •• •••• ••••• ••••• •••• •••      
5251 0 NS4 •••• ••• •••• ••••• •••• •••      
  H3   ••• ••• •••• ••••• •••• •••      
  H6   ••• •••• •••• ••••• •••• •••      
5454 0 NS51 •••• ••• ••••• ••••• •••• •••      
  H2   ••• •••• ••••• ••••• •••• •••      
  H4   ••• •••• ••••• ••••• •••• •••      
5754 0   ••• ••• ••••• ••••• •••• ••• •••••    
6061 TB HS20 •••• ••• •••• •••• ••• ••      
  TF   ••• •••• •••• •••• ••• ••      
6082 TB HS30 ••• ••• •••• •••• ••• ••      
  TF   ••• •••• •••• •••• ••• ••      
7020   HS17   ••• ••••   ••        
        •••• ••••   ••        
7022 TF   ••••• •• •••• •••     •••    
7075 TF   •••••   •••• ••   ••      

 

Wrought aluminium alloy composition limits (% weight)

AlloySiFeCuMnMgCrZnVTiBiGaPbZrLimits††Al
EachTotal
1050[7] 0.25 0.40 0.05 0.05 0.05     0.05           0.03   99.5 min
1060 0.25 0.35 0.05 0.03 0.03 0.03 0.05 0.05 0.03 0.03 0.03 0.03 0.03 0.03   99.6 min
1100 0.95 Si+Fe 0.05–0.20 0.05     0.10             0.05 0.15 99.0 min
1199[7] 0.006 0.006 0.006 0.002 0.006   0.006 0.005 0.002   0.005     0.002   99.99 min
2014 0.50–1.2 0.7 3.9–5.0 0.40–1.2 0.20–0.8 0.10 0.25   0.15         0.05 0.15 remainder
2024 0.50 0.50 3.8–4.9 0.30–0.9 1.2–1.8 0.10 0.25   0.15         0.05 0.15 remainder
2219 0.2 0.30 5.8–6.8 0.20–0.40 0.02   0.10 0.05–0.15 0.02–0.10       0.10–0.25 0.05 0.15 remainder
3003 0.6 0.7 0.05–0.20 1.0–1.5     0.10             0.05 0.15 remainder
3004 0.30 0.7 0.25 1.0–1.5 0.8–1.3   0.25             0.05 0.15 remainder
3102 0.40 0.7 0.10 0.05–0.40     0.30   0.10         0.05 0.15 remainder
4041 4.5–6.0 0.80 0.30 0.05 0.05   0.10   0.20         0.05 0.15 remainder
5005                               remainder
5052 0.25 0.40 0.10 0.10 2.2–2.8 0.15–0.35 0.10             0.05 0.15 remainder
5083 0.40 0.40 0.10 0.40–1.0 4.0–4.9 0.05–0.25 0.25   0.15         0.05 0.15 remainder
5086 0.40 0.50 0.10 0.20–0.7 3.5–4.5 0.05–0.25 0.25   0.15         0.05 0.15 remainder
5154 0.25 0.40 0.10 0.10 3.10–3.90 0.15–0.35 0.20   0.20         0.05 0.15 remainder
5356 0.25 0.40 0.10 0.10 4.50–5.50 0.05–0.20 0.10   0.06–0.20         0.05 0.15 remainder
5454 0.25 0.40 0.10 0.50–1.0 2.4–3.0 0.05–0.20 0.25   0.20         0.05 0.15 remainder
5456 0.25 0.40 0.10 0.50–1.0 4.7–5.5 0.05–0.20 0.25   0.20         0.05 0.15 remainder
5754 0.40 0.40 0.10 0.50 2.6–3.6 0.30 0.20   0.15         0.05 0.15 remainder
6005 0.6–0.9 0.35 0.10 0.10 0.40–0.6 0.10 0.10   0.10         0.05 0.15 remainder
6005A† 0.50–0.9 0.35 0.30 0.50 0.40–0.7 0.30 0.20   0.10         0.05 0.15 remainder
6060 0.30–0.6 0.10–0.30 0.10 0.10 0.35–0.6 0.05 0.15   0.10         0.05 0.15 remainder
6061 0.40–0.8 0.7 0.15–0.40 0.15 0.8–1.2 0.04–0.35 0.25   0.15         0.05 0.15 remainder
6063 0.20–0.6 0.35 0.10 0.10 0.45–0.9 0.10 0.10   0.10         0.05 0.15 remainder
6066 0.9–1.8 0.50 0.7–1.2 0.6–1.1 0.8–1.4 0.40 0.25   0.20         0.05 0.15 remainder
6070 1.0–1.7 0.50 0.15–0.40 0.40–1.0 0.50–1.2 0.10 0.25   0.15         0.05 0.15 remainder
6082 0.7–1.3 0.50 0.10 0.40–1.0 0.60–1.2 0.25 0.20   0.10         0.05 0.15 remainder
6105 0.6–1.0 0.35 0.10 0.10 0.45–0.8 0.10 0.10   0.10         0.05 0.15 remainder
6162 0.40–0.8 0.50 0.20 0.10 0.7–1.1 0.10 0.25   0.10         0.05 0.15 remainder
6262 0.40–0.8 0.7 0.15–0.40 0.15 0.8–1.2 0.04–0.14 0.25   0.15 0.40–0.7   0.40–0.7   0.05 0.15 remainder
6351 0.7–1.3 0.50 0.10 0.40–0.8 0.40–0.8   0.20   0.20         0.05 0.15 remainder
6463 0.20–0.6 0.15 0.20 0.05 0.45–0.9   0.05             0.05 0.15 remainder
7005 0.35 0.40 0.10 0.20–0.70 1.0–1.8 0.06–0.20 4.0–5.0   0.01–0.06       0.08–0.20 0.05 0.15 remainder
7022 0.50 0.50 0.50–1.00 0.10–0.40 2.60–3.70 0.10–0.30 4.30–5.20   0.20         0.05 0.15 remainder
7068 0-0.12 0-0.15 1.60–2.40 0–0.10 2.20–3.00 0–0.05 7.30–8.30   0-0.01       0.05–0.15     remainder
7072 0.7 Si+Fe 0.10 0.10 0.10   0.8–1.3             0.05 0.15 remainder
7075 0.40 0.50 1.2–2.0 0.30 2.1–2.9 0.18–0.28 5.1–6.1   0.20         0.05 0.15 remainder
7079 0.3 0.40 0.40–0.80 0.10–0.30 2.9–3.7 0.10–0.25 3.8–4.8   0.10         0.05 0.15 remainder
7116 0.15 0.30 0.50–1.1 0.05 0.8–1.4   4.2–5.2 0.05 0.05   0.03     0.05 0.15 remainder
7129 0.15 0.30 0.50–0.9 0.10 1.3–2.0 0.10 4.2–5.2 0.05 0.05   0.03     0.05 0.15 remainder
7178 0.40 0.50 1.6–2.4 0.30 2.4–3.1 0.18–0.28 6.3–7.3   0.20         0.05 0.15 remainder
8000                               remainder
7178                               remainder
†Manganese plus chromium must be between 0.12–0.50%. ††This column lists the limits that apply to all elements, whether a table column exists for them or not, for which no other limits are specified.