Martienssen W., Warlimont H. (Eds.). Handbook of Condensed Matter and Materials Data

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182 Part 3 Classes of Materials

cold working. This is not associated with any bene-

ﬁcial increases in strength but leads to deterioration

in the corrosion resistance by intergranular corrosion

(Fig. 3.1-16). It is necessary to avoid the formation

of continuous networks of β particles at the grain

boundaries. Individual β particles can be obtained by

a globulization treatment (200–250

◦

C), followed by

slow cooling.

Another means to increase strength is the addition

of Mn. Al

−

Mg alloys show an additional increase

in tensile strength, which is signiﬁcantly higher than

for binary Al–Mn alloys (Fig. 3.1-26). The alloys show

good toughness and can be used at low temperatures.

If the Mn content exceeds 0.6 wt%, the recrystalliza-

tion temperature can be increased to such an extent

that recrystallization does not occur during extrusion.

With extruded sections, there is an increase in tensile

strength and proof stress in the longitudinal direction

termed “press effect.”

3.1.2.7 Structure and Basic Mechanical

Properties of Wrought

Age-Hardenable Aluminium Alloys

Wrought Al–Cu–Mg and Al–Cu–Si–Mn (2xxx)

Alloys

The 2xxx series alloys usually contain 3.5to5.5wt%Cu

and additions of Mg, Si and Mn and residual Fe. They

show a signiﬁcant increase in tensile strength by aging

(310 to 440 MPa). Natural (room temperature) or artiﬁ-

cial aging (at elevated temperature) may be preferable,

depending on the alloy composition (Fig. 3.1-26). Addi-

tions of up to 1.5 wt% Mg increase both tensile strength

and proof stress. At these Mg contents, the Al-rich solid

solution is in equilibrium with the ternary Al

CuMg

phase which, together with the θ phase (Al

Cu), is

responsible for hardening. Mn additions increase the

strength (Fig. 3.1-27) and can also cause a press effect.

For achieving good ductility, the Mn content is limited

to ≈ 1wt%.

Wrought Al–Mg–Si (6xxx)

−

Si alloys are the most widely used wrought

age-hardenable alloys. Hardening is attributable to the

formation of the Mg

Si phase. The compositional range

of interest is 0.30 to 1.5wt% Mg, 0.20 to 1.6 wt% Si,

up to 1.0wt%Mn,andupto0.35 wt% Cr. This is

equivalent to about 0.40 to 1.6vol%Mg

Si and vary-

ing amounts of free Si and/or Mg. Some alloys are close

to the pseudo-binary section Al

−

Si, in others there

is a signiﬁcant excess of Si. This affects the maximum

500

400

300

200

100

01234567

Tensile strength R

0.2% p roof stress R

p0.2

(MPa)

Elongation

to fracture A (%)

p0.2

Copper content (%)

500

400

300

200

100

120

p0.2

Tensile strength R

0.2% proof stress R

p0.2

(MPa)

Manganese content (mass %)

Elongation

to fracture A (%)

Fig. 3.1-26a,b Behavior of wrought Al

−

Cu-alloys (a) Ef-

fect of copper on the strength of binary Al

−

Cu alloys; base

material 99.95 wt% Al, 1.6 mm thick sheet [1.23]. (1) Soft

annealed; (2) Solution annealed and quenched; (3) Natu-

rally aged; (4) Artiﬁcially aged.

(b) Effect of Mn on the

strengthofanAl

−

Mg alloy with approx. 4 wt% Cu

and 0.5 wt% Mg; naturally aged [1.23]

Part 3 1.2

Metals 1.2 Aluminium and Aluminium Alloys 183

320

240

160

0.2 0.4

0.6 0.8

1.0

1.2

1.4

Tensile strength R

(MPa)

Manganese content (mass %)

Fig. 3.1-27 Effect of Mg

Si on tensile strength [1.9]

(1) stoichiometric composition, (2) 0.3 wt% excess Mg,

(3) 0.3 wt% excess Si. The solid line refers to alloys that

were quenched + immediate ageing at 160

◦

C, the dot-

ted line represents data for alloys that were quenched +

intermediate ageing for 24 h at 20

◦

C + ageing at 160

◦

attainable strength values because of the resulting varia-

tions in the amount of Mg

Si, as shown in Fig. 3.1-28 for

the quenched and artiﬁcially aged condition. Additions

of 0.2to1.0 wt% Mn lead to an increase in the notch

impact toughness of Al

−

Si alloys (Fig. 3.1-29),

and affect the recrystallization behavior. Additions of

Cr cause similar effects.

Wrought Al–Zn–Mg- and Al–Zn–Mg–Cu Alloys

(7xxx)

Additions of Zn to Al lead to an insigniﬁcant increase in

strength. Combined additions of Zn and Mg cause age

hardening and thus an increase in strength (Fig. 3.1-28).

The sum of the Zn and Mg contents is limited to about

6–7% because of the risk of stress corrosion cracking

at higher levels in Cu-free Al

−

Mg alloys; this re-

sults in medium strength. Zr, Mn, and Cr are added to

reduce the tendency to recrystallize. If suitably heat-

treated, such alloys have adequate corrosion resistance.

It is important that cooling after solution treatment is

not too rapid and that the proper precipitation treatment,

usually step ageing, should be used. The alloys are of in-

terest for welded structures because of their low quench

Fig. 3.1-29 Effect of Mn and Fe on the notch impact

toughness of AlMgSi1 alloy 1 wt% Si and 0.75 wt% Mg;

artiﬁcially aged, ﬂat bars, 60× 10mm

[1.24]

01234567

400

300

200

100

Zinc content (mass %)

Tensile strength R (MPa)

Fig. 3.1-28 Effect of Zn and Mg on the strength and aging

effect of Al–Zn–Mg alloys [1.24] (1) Solution treatment

at 450

◦

C and quenching. (2) Solution treatment at 450

◦

and quenching plus natural aging for 3 months. (3) Ageing

effect i. e., the increase in strength attributable to natural

ageing; difference between (1) and (2)

0.2

0.4

0.6

0.8

1.0

Notch impact toughness (J/cm

)

Manganese content (mass %)

0.1 % Fe

0.3 % Fe

Part 3 1.2

184 Part 3 Classes of Materials

Elongation to fracture A (%)

Zinc content (mass %)

012345678

Tensile strength R

(MPa)

3 % Mg

1 % Mg

p0.2

600

500

400

300

200

100

Fig. 3.1-30 Effect of zinc on the tensile properties of Al–

Zn–Mg–Cu alloys; solution treated at 460

◦

C, quenched,

aged for 12 h at 135

◦

C, 1.5 wt% Cu [1.23]

sensitivity. The low-strength heat-affected zone formed

during welding is restored to full hardness without the

need for renewed solution treatment. Al

−

Mg alloys

usually contain 0.1to0.2 wt% Zr and some Ti in order

to improve their weldability and resistance to stress cor-

rosion cracking. Cu additions are avoided, despite their

favourable effect on stress corrosion cracking, because

they increase susceptibility to weld cracking.

Al–Zn–Mg–Cu Alloys

The addition of 0.5to2.0 wt% Cu strength-

ens Al

−

Mg alloys. Cu also reduces the tendency

for stress corrosion cracking so that the upper limit for

(Zn+Mg) can be increased to 9 wt%, provided additions

of Cr are also made. The Zn/Mg ratio should preferably

lie between 2 and 3. Al

−

Cu alloys can be

aged both naturally and artiﬁcially. They attain the high-

est strength levels of all aluminium alloys. The actual

hardening mechanism is attributable to Mg and Zn. Cu

increases the rate of aging and acts as a nucleus for the

hardening phases. Figure 3.1-30 shows some properties

as a function of the Zn content at constant Cu content

and two different Mg contents.

3.1.2.8 Structure and Basic Mechanical

Properties of Aluminium Casting

Alloys

Al–Si Casting Alloys

Due to the Al

−

Si eutectic (Fig. 3.1-12), these al-

loys, containing 5 to ≤ 20 wt% Si, have good casting

Elongation to fracture A (%)

Silicon content (mass %)

Tensile strength R

(MPa)

10 12

200

150

100

Fig. 3.1-31 Effect of Si on the strength and ductility of

−

Si casting alloys; modiﬁed and unmodiﬁed sand cast-

ings. [1.9] (1) modiﬁed; (2) unmodiﬁed

properties. The tensile strength increases with the Si

content (Fig. 3.1-31). Apart from Si other elements

may be added, e.g., for the modiﬁcation of the eu-

tectic. Cu is present in residual amounts and impairs

chemical resistance if levels exceed 0.05 wt%. Addi-

tions of about 1 wt% Cu yield an increase in solid

solution hardening and thus reduce the tendency for

smearing during machining. Residual Fe reduces stick-

ing tendency, but leads to the formation of β-AlFeSi

needles which reduce strength and ductility. Therefore

the Fe content must be limited. An addition of Mn

has a favorable effect on the sticking tendency. Mn

leads to the formation of a quaternary phase; but it

poses no problem because of its globular shape. “Pis-

ton alloys” have hypereutectic compositions of up to

25 wt% Si. During solidiﬁcation, primary Si crystals are

formed which increase wear strength and reduce thermal

expansion.

Al–Si–Mg Casting Alloys

These alloys contain about 5 wt%, 7 wt%, or 10 wt% Si

and between 0.3and0.5 wt% Mg. The optimum amount

of Mg decreases with increasing Si content. Mg causes

high strength and a moderate ductility depending on the

Part 3 1.2

Metals 1.2 Aluminium and Aluminium Alloys 185

Magnesium content (mass %)

280

240

200

160

120

110

100

0 0.2

0.4

0.6

Tensile strength R

0.2% proof stress R

p0.2

(MPa)

Elongation to fracture A (%)

Brinell hardness HB

320

p0.2

Fig. 3.1-32 Effect of Mg on the mechanical properties of

G-AlSi10Mg casting alloy (with 9.5wt%Si, 0.45 wt% Fe

and 0.3 wt% Mn), sand cast and artiﬁcially aged [1.25–27]

Magnesium content (mass %)

Tensile strength R

0.2% proof stress R

p0.2

(MPa)

Elongation to fracture A (%)

Brinell hardness HB

120

100

2468101214160

Magnesium content (mass %)

Tensile strength R

0.2% proof stress R

p0.2

(MPa)

Elongation to fracture A (%)

Brinell hardness HB

120

100

2468101214160

p0.2

Fig. 3.1-33a,b Effect of Mg on the mechanical properties of Al–Mg casting alloys, sand cast, untreated and ho-

mogenised [1.9].

(a) As-cast condition. (b) Homogenized

temper (Fig. 3.1-32). The alloys can be age hardened

both naturally and artiﬁcially. Fe leads to a reduction

in sticking tendency, but also to a drastic reduction in

ductility.

Al–Mg Casting Alloys

These alloys contain 3–12 wt% Mg. Strength increases

with increasing Mg content (Fig. 3.1-33). Above about

7 wt% Mg, the alloy has to beheat-treated to homogenise

the structure and thus obtain good tensile properties.

With Mg contents of up to 5 wt%, Si additions of up to

1 wt% are possible, and these lead mainly to improve-

ments in the casting properties. The addition of Si causes

hardening due to the formation of Mg

Si.

Al–Zn–Mg Casting Alloys

They contain 4 to 7 wt% Zn and 0.3to0.7 wt% Mg.

They can be naturally or artiﬁcially age hardened in the

as-cast condition, without the need for prior solution

treatment. Mg has a signiﬁcant effect on the mechan-

ical properties in the aged condition (Fig. 3.1-34). If the

Mg content is limited, Al

−

Mg casting alloys can

exhibit particularly good elongation to fracture.

Part 3 1.2

186 Part 3 Classes of Materials

Magnesium content (mass %)

Tensile strength R

0.2% proof stress R

p0.2

(MPa) Elongation to fracture A (%)

320

240

160

0 0.5 1.0 1.5 2.0

4% Zn

5% Zn

p0.2

Fig. 3.1-34 Effect of Mg on the strength of cast Al–Zn–Mg

alloys; sand casting, artiﬁcially aged [1.9]

3.1.2.9 Technical Properties

of Aluminium Alloys

The applications of aluminium and its alloys are de-

pending on the properties. In most cases, mechanical

properties are an important criterion for assessing the

suitability of an Al alloy for a speciﬁc application.

Other properties, such as electrical conductivity or cor-

rosion resistance, may also be included in the assessment

process.

Mechanical Properties

Hardness. The Brinell hardness number HB ranges

from 15 for unalloyed Al in the soft temper to about

140 for an artiﬁcially aged Al

−

1.5wt%Cu

alloy.

Tensile Strength. Figures 3.1-35 and 3.1-36 indicate

the typical levels of strength attainable with wrought

and cast aluminium alloys, respectively. There will be

a range of tensile strengths in speciﬁc alloying sys-

tems because of possible additional increases in strength

due to hardening by cold work or precipitation. The

different alloying elements cause differing degrees of

strengthening.

600

500

400

300

200

100

Tensile strength R

(MPa)

Alloy

AlMgSi1

AlMg3

AlMgSi0.5

AlMg2Mn0.3

AlZn4.5Mg1

AlMg4.5Mn

AlCuMg2

AlZnMgCu0.5

AlZnMgCu1.5

AlCuMg1

Al99.8

Al99.5

Al99

AlMn

AlMg1

Fig. 3.1-35 Ranges of tensile strength for some important

wrought aluminium alloys [1.9]

500

400

300

200

100

Tensile strength R

(MPa)

Alloy

G-AlMg3

G-AlMg5

G-AlMg3Si

G-AlSi12

G-AlSi6Cu4

G-AlSi5Mg

G-AlSiCu3

G-AlSi10Mg

G-AlMg9

G-AlMg10

G-AlSi9Mg

G-AlSi7Mg

G-AlCu4Ti

G-AlCu4TiMg

Fig. 3.1-36 Ranges of tensile strength for some important

aluminium casting alloys [1.9]

Strength at Elevated Temperatures.

An example of the

temperature and time dependence of the different mech-

anical properties is given in Fig. 3.1-37. With regard to

the resistance to softening the materials can be classiﬁed

as follows, depending on their temper:

•

Wrought alloys in the soft temper and as-cast non-

age-hardenable casting alloys are all practically

thermally stable.

•

For cold worked wrought alloys, partially annealed

to obtain an intermediate temper, the increase in

Part 3 1.2

Metals 1.2 Aluminium and Aluminium Alloys 187

100

400

300

200

400300200100

Test or annealing temperature (°C)

Strength (MPa)

10 h

4 h

N = 10

Fig. 3.1-37 Properties of 6061-T6 at elevated temperatures;

1.0wt%Mg, 0.6wt%Si, 0.3 wt% Cu, 0.25 wt% Cr, artiﬁ-

cially aged [1.9]. (1) tensile strength R

at 20

◦

C, (2) stress

rupture strength, (3) duration of exposure, (4) fatigue

strength, (5) tensile strength at test temperature, (6) solution

treated

400

300

200

100

0.25 0.5 1 6 12

230

100

360

180

720

1200

1000

800

600

400

200

0.25 0.5 1 6 12

230

100

360

180

720

0.2% proof stress R

p0.2

(MPa)

300°C

250°C

130°C

160°C

75°C

100°C

75°C

100°C

130°C

160°C

200°C

300°C

250°C

Tensile strength R

(MPa)

(h)

(d)

Exposure time

Elongation to fracture A (%)

Brinell hardness HB (MPa)

300°C

250°C

160°C

200°C

75, 100, 130°C

75°C

100°C

130°C

160°C

200°C

250°C

300°C

(h)

(d)

Exposure time

Fig. 3.1-38a–d Effect of temporary exposure to elevated temperature on the mechanical properties of artiﬁcially aged

AlSi1MgMn [6082] at 20

◦

C [1.9]. (a) tensile strength; (b) 0.2% proofstress R

0.2; (c) elongation to fracture A; (d) Brinell

hardness

strength due to forming is diminished with increas-

ing temperature and exposure time.

•

Artiﬁcially aged alloys do not undergo any per-

manent changes on annealing up to approaching

the ageing temperature. At higher temperatures,

aging continues from the point where it was inter-

rupted during the aging process (Figs. 3.1-38 and

3.1-39).

•

Naturally aged alloys usually exhibit increased hard-

ening when exposed to higher temperatures as

a result of artiﬁcial ageing. At higher temperatures,

the behavior is similar to that of artiﬁcially aged

alloys.

High Temperature Mechanical Properties in Short-

Term Tests.

In materials that are not thermally stable,

there will be an effect due to irreversible changes in

properties. Its magnitude depends on the temperature

and duration of exposure, Figs. 3.1-40 and 3.1-41.

Creep Behavior. Creep of Al alloys starts to play an

important role at temperatures above 100 to 150

◦

(Figs. 3.1-42 and 3.1-43). Material, amount of cold work

Part 3 1.2

188 Part 3 Classes of Materials

400

300

200

100

120

100

120

100

90 180

130

90 180

360

Tensile strength R

(MPa)Brinell hardness HBBrinell hardness HB

Time (h)

175°C

250°C

300°C

350°C

100°C

150°C

200°C

250°C

100°C

160°C

250°C

a) b) c)

Time (h) Time (h)

Fig. 3.1-39a–c Effect of temporary exposure to elevated temperature on the hardness and tensile strength at 20

◦

C of cast

G-AlSi10Mg [43000, AlSi10Mg(a)] alloy, artiﬁcially aged [1.28].

(a) 0–4h; (b) 1–180 d; (c) 1–360 d

100 200 3000

High-temperature tensile strength (MPa)

T(°C)

200

160

120

G-AlMg5

G-AlMg5Si

p0.2

Fig. 3.1-40 High-temperature tensile strength of G-AlMg5

[51300] and G-AlMg5Si [51400] casting alloys, sand

cast, after 30 min prior exposure to the test tempera-

ture [1.29]

and degree of age-hardening can affect creep behavior

in various ways. With non-age-hardenable alloys, the

effect of cold working is more pronounced at low tem-

peratures, below about 150

◦

C. At higher temperatures,

the behavior rapidly approaches that of the softened ma-

terial. Thus, more highly alloyed materials in the soft

temper may exhibit better creep properties than cold

worked alloys that are less highly alloyed. Artiﬁcially

High-temperature tensile strength (MPa)

T(°C)

120

100

150 200

250 300

350

Fig. 3.1-41 High-temperature tensile strength of cast-

ing alloys [1.28]. (1) As-cast G-AlSi12 alloy [44300,

AlSi12(Fe)]. (2) G-AlSi10Mg alloy [43000, AlSi10Mg(a)]

after preheating for 8 days at the test temperature

Part 3 1.2

Metals 1.2 Aluminium and Aluminium Alloys 189

Creep rupture strength (MPa)

400

200

100

050

100

150 200

250 300

T(°C)

AlMgSiF32

Fig. 3.1-42 Creep rupture behavior of 6082, AlSi1MgMn,

T6 alloy, strain-hardened, min. tensile strength 320 MPa;

extruded rods, 25 mm diameter [1.30,31]

400

200

100

200

300

10 h

T(°C)

Creep rupture strength (MPa)

Fig. 3.1-43 Creep rupture behavior of AlSi10MgCa

[43000] casting alloy, artiﬁcially aged, 100 h prior exposure

to the test temperature [1.30,31]

aged alloys should only be exposed for prolonged peri-

ods to temperatures that are signiﬁcantly lower than the

temperature of artiﬁcial ageing, otherwise over-ageing

will lead to a complete loss of strength.

Mechanical Properties at Low Temperatures. Based

on its fcc crystal structure, Al and its alloys show

neither a rapid increase in yield stress nor a rapid de-

crease in fracture toughness with decreasing temperature

(Figs. 3.1-44 – 3.1-46). Tests carried out on Al

−

Mn,

−

Mg, Al

−

Si, Al

−

Mg, and Al

−

wrought alloys at −268

◦

C showed that the values

of elongation to fracture at extremely low tempera-

tures were even higher than at room temperature. In

most cases, tensile strength and 0.2% proof stress

increased weakly with decreasing temperature. Cast-

ing alloys behave similar to wrought alloys at low

temperatures. The behavior will depend on composi-

tion, temper (especially size, shape and distribution

of precipitates), and on the casting process used

(Fig. 3.1-47).

Fatigue. There is a marked effect of composition, heat

treatment, and method of processing on fatigue strength.

Solid solution hardening, cold work, and age hard-

ening all lead to an increase in fatigue strength. For

a given alloy composition, extruded sections usually

have ahigher fatigue strength thansheet or forgings. Fine

grains are generally beneﬁcial whereas coarse grains and

coarse intermetallic phase particles can lead to a reduc-

tion in fatigue strength. Often there is an increase in

fatigue strength with decreasing sample thickness, es-

pecially with bending stresses. Moreover, the effect of

roughness or surface defects in thin specimens is usu-

ally less than that in thicker samples. With wrought

aluminium alloys, there is a marked difference be-

tween age-hardenable alloys and non-age-hardenable

alloys. It manifests itself in the shape of the S–N

curve (Fig. 3.1-47), which is almost horizontal after

about 10

cycles for non-age-hardenable alloys and after

about 10

cycles for age-hardenable alloys. Fig-

Tensile strength R

0.2% proof stress R

p0.2

(MPa)

250

200

150

100

–200 –100

T(°C)

Elongation A (%)

T(°C)

p0.2

Fig. 3.1-44a,b Mechanical properties of unalloyed aluminium AA

1100 (Al99) at low temperatures [1.9].

(a) Tensile strength R

;

(b) Elongation A

Part 3 1.2

190 Part 3 Classes of Materials

400

300

200

100

–200 –100 0 20

–200 –100 0 20–200 –100 0 20

T(°C)

Tensile strength R

0.2% proof stress R

p0.2

(MPa)

AlMg4Mnw24

AlMg2.5w17

AlMg4.5Mnw28

T(°C)

Elongation A (%) Reduction of area Z (%)

T(°C)

AlMg4.5Mnw28

AlMg4Mnw24

AlMg2.5w17

AlMg2.5w17 +

AlMg4Mnw24

AlMg4.5Mnw28

Fig. 3.1-45a–c Mechanical properties at low temperatures for some Al

−

Mg and Al

−

Mn alloys in the soft temper [1.9].

(a) Tensile strength R

and 0.2 proof stress R

p0.2

; (b) Elongation A



; (c) reduction of area AlMg4Mn (≈ 5086, AlMg4), W24

∼O/H111; AlMg2.5 (≈ 5052, AlMg2.5), W17 ∼O/H111; AlMg4.5Mn (≈ 5083, AlMg4.5Mn), W28 ∼O/H111

p0.2

Tensile strength R

0.2% proof stress R

p0.2

(MPa)

400

300

200

100

–200

–100 0 20

–200

–100 0 20

Elongation A

reduction of area Z

(MPa)

5052-0

5052-H32

5052-H34

5052-H38

a) b)

T(°C) T (°C)

Fig. 3.1-46a,b Effect of cold working on the tensile properties of AlMg2.5 (5052) at low temperatures [1.9]. (a) Tensile

strength and 0.2 proof stress;

(b) Elongation and reduction of area

ure 3.1-48 illustratesthat the choice of 10

cycles as

the ultimate number of stress cycles is regarded as ade-

quate. Figure 3.1-49 shows fatigue curves for a number

of casting alloys.

Technological Properties

Abrasion Resistance. The wear resistance of Al al-

loys is low, especially in the absence of lubricants.

There is no relation between hardness, strength and

Part 3 1.2

Metals 1.2 Aluminium and Aluminium Alloys 191

350

300

250

200

150

100

Elongation to fracture A (%)

Tensile strength R

(MPa)

–200 –100 0 20

T(°C)

Fig. 3.1-47 Mechanical properties of artiﬁcially aged

G-AlSi12 and G-AlSi10Mg casting alloys at low tem-

peratures [1.28]. The solid line represents G-AlSi10Mg,

artiﬁcially aged; the dotted line represents G-AlSi12, as-

cast

10 10 10 1010

56784

Number of stress cycles N

Bending fatigue strength σ

(MPa)

400

300

200

100

AlZnMgCu1.5F53

AlMg5W25

Table 3.1-13 Typical values of strain-hardening exponent n and degree of anisotropy r for some aluminium-base materials

based on data from various sources [1.9]; n.a. – not available

Material, Alloy Temper n r

Al99.5 1050A O/H111 0.25 0.62

AlMn1 3103 O/H111 0.15 n.a.

AlMg3 5754 O/H111 0.20 0.64

AlMg3 5754 H14 0.16 0.75

AlMg3 5754 H18 0.12 1.10

AlMg2Mn0.8 5049 O/H111 0.20 0.66

AlMg2Mn0.8 5049 H112 0.20 0.92

AlMg4.5Mn 5063 O/H111 0.15 n.a.

Number of stress cycles N

Bending fatigue strength σ

(MPa)

180

160

140

120

100

Fig. 3.1-49 Bending fatigue strength of two aluminium

pressure die-casting alloys; ﬂat samples with cast skin [1.9].

(1) Fracture; (2) Fracture, with evidence of defect; (3) No

fracture; (4) GD-AlSi6Cu3; (not in EN); (5) GD-AlSi12 [≈

44300, AlSi12(Fe)]

abrasion resistance. Under suitable conditions of lubri-

cation, aluminium alloys can be safely used where they

will encounter friction, as shown by their widespread

use in the fabrication of pistons and sliding bearings.

Wear can be drastically reduced by the suitable surface

treatments.

Sheet Formability. Typical values for deep-drawing in-

dices for commonly used sheet materials are shown in

Fig. 3.1-50, whereas typical values of strain-hardening

exponent n and degree of anisotropy r are given in

Table 3.1-13. The r value is strongly dependent on the

manufacturing process in particular, as is the case with

all texture-dependent properties. In general, materials

with high n and r values are deep-drawable.

Fig. 3.1-48 Typical S-Ncurves for reverse bending tests on

an age-hardenable and a non-age-hardenable alloy [1.9],

AlZnMgCu1.5 F53 (≈ 7075, AlZn5.5MgCu, T651) and

AlMg5 (≈ 5019, AlMg5), W25

Part 3 1.2