ALUMINUM

Chemical Composition and Properties of Aluminum Alloys

 

The Benefits of Aluminum

  • Aluminum is a light metal, about the third of the density of steel, copper, and brass.
  • Aluminum has good corrosion resistance to common atmospheric and marine atmospheres. Its corrosion resistance and scratch resistance can be enhanced by anodizing.
  • Aluminum has high reflectivity and can be used for decorative applications.
  • Some aluminum alloys can match or even exceed the strength of common construction steel.
  • Aluminum retains its toughness at very low temperatures, without becoming brittle like carbon steels.
  • Aluminum is a good conductor of heat and electricity. When measured by equal cross-sectional area, electrical grade aluminum has conductivity which is approximately 62% of electrical grade annealed copper. However, when compared using equal weight, the conductivity of aluminum is 204% of copper.
  • Aluminum is readily worked and formed using a wide variety of forming processes including deep- drawing and roll forming.
  • Aluminum is non-toxic and is commonly used in contact with foodstuffs.
  • Aluminum can be readily recycled.

ALUMINUM ALLOY DESIGNATIONS

Alloy Designation System for Wrought Sheet Products

Aluminum alloys for sheet products are identified by a four-digit numerical system which is administered by the Aluminum Association. The alloys are conveniently divided into eight groups based on their principal alloying element. The first digit identifies the alloy group as follows:

ALLOY GROUP

PRINCIPAL ALLOYING ELEMENT

 

1xxx

Unalloyed Aluminum

Purity of 99.0% or Greater

2xxx

Copper

Heat Treatable Alloys

3xxx

Manganese

 

4xxx

Silicon

Low Melting Point Alloys

5xxx

Magnesium

 

6xxx

Magnesium and Silicon

Heat Treatable Alloys

7xxx

Zinc

Heat Treatable Alloys

8xxx

Other Elements

 

The last two digits in the 1xxx group correspond with the two digits after the decimal which indicate the minimum aluminum content. For example the aluminum content of 1060 is 99.60% minimum, 1100 is 99.00% minimum, 1350 is 99.50% minimum and so on.

The last two digits of the other groups are sequential numbers issued by the Aluminum Association to ensure each alloy is uniquely identified.

The second digit in all the groups indicates a minor modification of the basic alloy. For instance, 5252 is the second modification of 5052 alloy.

ALUMINUM TEMPER DESIGNATIONS

The temper designation follows the alloy code and is separated by a hyphen.

-F As Fabricated: Applies to products of rolling or forming where there is no special control over the thermal or work-hardening conditions. Since mechanical properties may vary widely, no limits have been assigned. This temper usually applies to sheet products which are at intermediate stages of production.

-H Strain-Hardened: Applies to wrought products which are strengthened by cold-rolling or cold-working.

-O Annealed: Applies to wrought products which have been heated above the recrystallization temperature to produce the lowest tensile strength condition of the alloy.

DESIGNATIONS OF THE –H STRAIN HARDENED TEMPERS

The First Digit

There are three different methods used to achieve the final temper of strain hardened material.

H1 Strain Hardened Only: Applies to products which are strain hardened to obtain the desired strength level without any subsequent thermal treatment.

H2 Strain Hardened And Partially Annealed: Applies to products that are strain hardened to a higher strength level than desired, followed by a partial anneal (or “back anneal”) which reduces the strength to the desired level.

H3 Strain Hardened And Stabilized: This designation only applies to magnesium-containing alloys which gradually age- soften at room temperature after strain hardening. A low temperature anneal is applied which stabilizes the properties.

The Second Digit

The amount of strain hardening, and hence the strength level, is indicated by a second digit.

-Hx2

Quarter hard

-Hx4

Half hard

-Hx6

Three quarter

-Hx8

Full hard

-Hx9

Extra hard (the minimum tensile strength exceeds that of the Hx8 temper by 2 ksi or more)

Hx1, Hx3, Hx5 and Hx7 tempers are intermediate between those defined above.

The mechanical property limits that correspond to each temper designation can be found by referring to an appropriate aluminum standard such as the Aluminum Association Standards and Data or ASTM B 209.

The Third Digit

A third digit is sometimes used to indicate a variation of the basic two-digit temper.

HEAT TREATMENT TEMPERS

Alloys in the 2xxx, 6xxx and 7xxx groups can be strengthened by a heat treatment process. The aluminum is heat treated by carrying out a solution treatment process, in which the metal is heated to an elevated temperature followed by rapid cooling, then a precipitation hardening process (or “aging” process). The tempers are designated by –T followed by a digit. Some common –T tempers are as follows:

T3 Solution heat-treated, cold worked, and naturally aged: Applies to products that are cold-worked to improve strength after solution heat-treatment, or which the effect of flattening or straightening is recognized in mechanical property limits.

T4 Solution heat-treated and naturally aged: Applies to product that are allowed to age harden at room temperature following a solution treatment.

T6 Solution heat-treated and artificially aged: Applies to products that are reheated to a low temperature following a solution treatment. This allows the metal to achieve its highest heat-treated strength level.

CHEMICAL COMPOSITION LIMITS FOR ALUMINUM ALLOYS

Composition in percent by weight according to The Aluminum Association. The values indicate maximum limits unless shown as a range or a minimum.

Alloy

Si

Fe

Cu

Mn

Mg

Cr

Zn

Ti

OTHERS

OTHERS

Al

EACH

TOTAL

MIN.

1070

0.20

0.25

0.04

0.03

0.03

0.04

0.03

0.03

99.70

1060

0.25

0.35

0.05

0.03

0.03

0.05

0.03

0.03

99.60

 

1050

0.25

0.40

0.05

0.05

0.05

0.05

0.03

0.03

99.50

1350

0.10

0.40

0.05

0.01

0.01

0.05

0.03

0.10

99.50

1145

0.55 Si + Fe

0.05

0.05

0.05

0.05

0.03

0.03

99.45

1100

0.95 Si + Fe

0.05-0.20

0.05

0.10

0.05

0.15

99.00

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

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

3003

0.6

0.7

0.05-0.20

1.0-1.5

0.10

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

3004

0.30

0.7

0.25

1.0-1.5

0.8-1.3

0.25

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

3005

0.6

0.7

0.30

1.0-1.5

0.20-0.6

0.10

0.25

0.10

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

3104

0.6

0.8

0.05-0.25

0.8-1.4

0.8-1.3

0.25

0.10

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

4004

9.0-10.5

0.8

0.25

0.10

1.0-2.0

0.20

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

4104

9.0-10.5

0.8

0.25

0.10

1.0-2.0

0.20

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

4043

4.5-6.0

0.8

0.30

0.05

0.05

0.10

0.20

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

4045

9.0-11.0

0.8

0.30

0.05

0.05

0.10

0.20

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

5005

0.30

0.7

0.20

0.20

0.50-1.1

0.10

0.25

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

5050

0.40

0.7

0.20

0.10

1.1-1.8

0.10

0.25

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

5052

0.25

0.40

0.10

0.10

2.2-2.8

0.15-0.35

0.10

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

5252

0.08

0.10

0.10

0.10

2.2-2.8

0.05

0.03

0.10

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

5056

0.30

0.40

0.10

0.05-0.20

4.5-5.6

0.05-0.20

0.10

0.05

0.15

Rem.

 

 

 

 

 

 

 

 

 

 

 

 

5657

0.08

0.10

0.10

0.03

0.6-1.0

0.05

0.02

0.05

Rem.

5182

0.20

0.35

0.15

0.20-0.50

4.0-5.0

0.10

0.25

0.10

0.05

0.15

Rem.

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

Rem.

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

Rem.

Rem.=Remainder

ALUMINUM SHEET & COIL PUBLISHED DIMENSIONAL TOLERANCES

Thickness Tolerances for Aluminum Sheet

Specified Thickness (Inches) Thickness (Tolerance for widths up to 39.37˝ )

Over

Thru

Inches plus and minus

0.0059

0.016

0.0010

0.016

0.025

0.0015

0.025

0.039

0.0020

0.039

0.047

0.0025

0.047

0.063

0.0030

0.063

0.098

0.0035

0.098

0.126

0.0045

0.126

0.158

0.0055

0.158

0.197

0.0070

 

 

 

The above are the published thickness tolerances in ANSI-H35.2 for all sheet alloys not included in the Aerospace Alloys Table or specified for aerospace applications.

Thickness Tolerances for Aerospace Alloys

Specified Thickness (Inches) Thickness (Tolerance for widths up to 39.37˝ )

Over

Thru

Inches plus and minus

0.0059

0.010

0.0010

0.010

0.039

0.0015

0.039

0.079

0.0020

0.079

0.098

0.0025

0.098

0.126

0.0035

0.126

0.158

0.0040

0.158

0.197

0.0055

The above are the published thickness tolerances in ANSI-H35.2 for aerospace alloys 2024 and 7075.

Width Tolerances for Slit Coil

Specified Thickness

 

Specified Width (inches)

 

Up Thru 6

 

Over 6

Over 12

Over 24

(Inches)

 

Thru 12

Thru 24

Thru 48

 

 

0.006-0.125

0.010

 

164

132

364

0.126-0.186

0.012

 

132

132

116

ANSI-H35.2

Lateral Bow (or “Camber”) Limits for Slit Coil

Allowable deviation of an edge from a 6ft. straight line

Specified

 

 

 

 

 

 

Specified

Width (inches)

 

 

 

Thickness

12 Thru 1

 

 

Over 1

Over 2

Over 4

Over 10

 

 

(Inches)

 

 

 

 

 

 

Thru 2

Thru 4

Thru 10

 

 

 

0.006-0.064

34

 

 

 

 

 

916

38

14

316

 

 

0.065-0.125

 

 

 

 

 

38

14

316

 

 

TYPICAL MECHANICAL PROPERTIES

The following typical properties are not guaranteed since in most cases they are averages for various sizes and methods of manufacture and may not be exactly representative of any particular product or size. The data is intended for comparing alloys and tempers and should not be used for design purposes.

 

 

Tensile

Yield

Elongation (%) for the

Tensile

Yield

Elongation (%) for the

 

 

Strength

Strength

following gauge ranges:

Strength

Strength

following gauge ranges:

Alloy

Temper

(ksi)

(ksi)

0.010-0.050˝

0.051-.125˝

(MPa)

(MPa)

0.25-1.25mm

1.26-3.0mm

1100

O

13

5

30

32

89.6

34.5

30

6

 

H12

16

15

4

12

110.3

103.4

4

12

 

H14

18

17

3

10

124.1

117.2

3

10

 

H16

21

20

2

8

144.8

137.9

2

8

 

H18

24

22

2

6

165.5

151.7

2

6

1350

O

12

4

34

42

82.7

27.6

34

42

 

H12

14

12

5

12

96.5

82.7

5

12

 

H14

16

14

3

9

110.3

96.5

3

9

 

H16

18

16

3

8

124.1

110.3

3

8

 

H19

27

24

2

6

186.2

165.5

2

6

2024

O

27

11

18

20

186.2

75.8

18

20

 

T3

70

50

16

18

482.6

344.7

16

18

 

T4

68

47

20

19

468.8

324.1

20

19

3003

O

16

6

30

33

110.3

41.4

30

33

 

H12

19

18

9

11

131.0

124.1

9

11

 

H14

22

21

3

7

151.7

144.8

3

7

 

H16

26

25

3

5

179.3

172.4

3

5

 

H18

29

27

3

5

199.9

186.2

3

5

3004

O

26

10

19

23

179.3

68.9

19

23

 

H32

31

25

6

15

213.7

172.4

6

15

 

H34

35

29

5

10

241.3

199.9

5

10

 

H36

38

33

5

8

262.0

227.5

5

8

 

H38

41

36

4

6

282.7

248.2

4

6

3005

O

20

8

22

23

137.9

55.2

22

23

 

H12

26

24

5

13

179.3

165.5

5

13

 

H14

29

28

4

9

199.9

193.1

4

9

 

H16

31

30

3

5

213.7

206.8

3

5

 

H18

37

36

2

3

255.1

248.2

2

3

5005

O

18

6

22

25

124.1

41.4

22

25

 

H12

20

19

5

9

137.9

131.0

5

9

 

H14

23

22

4

7

158.6

151.7

4

7

 

H16

26

25

3

5

179.3

172.4

3

5

 

H18

29

28

2

2

199.9

193.1

2

2

 

H32

20

17

8

9

137.9

117.2

8

9

 

H34

23

20

6

8

158.6

137.9

6

8

 

H36

26

24

5

6

179.3

165.5

5

6

 

H38

29

27

3

4

199.9

186.2

3

4

5050

O

21

8

20

25

144.8

55.2

20

25

 

H32

25

21

9

13

172.4

144.8

9

13

 

H34

28

24

5

10

193.1

165.5

5

10

 

H36

30

26

4

7

206.8

179.3

4

7

 

H38

32

29

2

4

220.6

199.9

2

4

5052

O

28

13

20

21

193.1

89.6

20

21

 

H32

33

28

7

10

227.5

193.1

7

10

 

H34

38

31

6

8

262.0

213.7

6

8

 

H36

40

35

4

5

275.8

241.3

4

5

 

H38

42

37

3

4

289.6

255.1

3

4

5056

O

42

22

23

24

289.6

151.7

23

24

 

H38

60

50

6

13

413.7

344.7

6

13

5182

O

40

21

21

25

275.8

144.8

21

25

 

H32

41

22

20

21

282.7

151.7

20

21

 

H34

48

37

11

14

330.9

255.1

11

14

 

H36

51

42

9

11

351.6

289.6

9

11

 

H38

54

47

6

7

372.3

324.1

6

7

6061

O

18

8

25

26

124.1

55.2

25

26

 

T4

35

21

22

24

241.3

144.8

22

24

 

T6

45

40

12

17

310.3

275.8

12

17

7075

O

33

15

16

18

227.5

103.4

16

18

 

T6

83

73

11

12

572.3

503.3

11

12

TYPICAL PHYSICAL PROPERTIES

 

Average1

 

 

Thermal

Electrical Conductivity at 68°F

Electrical

 

Coeffecient of

Melting

 

(Percent of International

Resistivity

 

Thermal

 

Conductivity

Annealed Copper Standard)

at 68°F

 

Expansion

Range 2,3

Density

(English

 

 

(Ohms-Cir.

Alloy

Equal

Equal

68° to 212°F

Approximately

(lbs/cubic in.)

Units4)

Mil/Foot)

 

(°F)

(°F)

 

 

Volume

Volume

 

 

 

 

 

 

 

 

 

1100

13.1

1190-1215

0.098

1520

59

194

18

1350

13.2

1195-1215

0.0975

1625

62

204

17

2024-O

12.9

935-11805

0.100

1340

50

160

21

2024-T3,T4

12.9

935-11805

0.100

840

30

96

35

2024-T6

12.9

935-11805

0.100

1050

38

122

27

3003

12.9

1190-1210

0.099

1200

48

156

22

3004

13.3

1165-1210

0.098

1100

41

134

25

3005

13.1

1175-1210

0.098

1190

45

148

23

5005

13.2

1170-1210

0.098

1390

52

172

20

5050

13.2

1155-1205

0.097

1340

50

165

21

5052

13.2

1125-1200

0.097

960

35

116

30

5056

13.4

1055-1180

0.096

790

28

95

37

5182

13.4

1055-1180

0.096

790

28

95

37

5657

13.2

1180-1215

0.097

960

35

116

30

6061-O

13.1

1080-12056

0.098

1250

47

155

22

6061-T4

13.1

1080-12056

0.098

1070

40

132

26

6061-T6

13.1

1080-12056

0.098

1160

43

142

24

1Coefficient to be multiplied by 10-6. Example 12.2 x 10-6 = 0.0000122.

2Melting ranges shown apply to wrought products of 14 inch thickness or greater.

3Based on typical composition of the indicated alloys.

4English units = btu-in/ft2hr °F.

5Eutectic melting is not eliminated by homogenization.

6Eutectic melting can be completely eliminated by homogenization