1. Characterization of forming behavior of AA5754
at elevated temperature
1
BY
Amit Kumar
(12ME61R07)
Under the supervision of
Dr . S. K. Panda
Department of Mechanical Engineering
Indian Institute of Technology, Kharagpur

2. Content
Introduction
Literature survey
Objectives
2
Methodology
Results and discussions
Conclusions
References

3. Introduction(contd..)
3
Fig1: Stretch forming process
 Commonly used sheet forming processes:
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Fig2: Deep drawing process
 A complex stamping involves combination of stretch forming and deep drawing to which
bending and unbending added.
Fig 3: Limiting formability of AA5754 compare to conventional low carbon steel.

4.  Improvement in formability:
4
Fig 4: Hydroforming
 High pressure facilities.
 Cycle time is high.
 Work piece should be conducting.
 Tooling cost is very high.
www.thefabricator.com
Introduction(contd..)
Conventional way:
• Lubrication, blank holding force and modification in tooling design.
Advanced technique:
Fig 5:Electromagnetic Forming.

5. Introduction(contd..):
5
o It is process carried out above the range
of cold working but below the recrystallization
temperature of the metal.
o Temperature range for the forming at high
temperature:
Fig 6: Warm forming process
Warm forming
www.thefabricator.com
Toros, Ozturk. Journal of Materials Processing Technology 207(2008) I-12.
 Reduces the forces required to perform the operation.

6. Literature survey:
6
1. Naka and Yoshida, 1999 conducted tensile tests and deep drawing experiment on AA5083
at various temperatures and strain rates.
Parameters: Temperature range - (25 – 250 °C).
Strain rates - 5.6 X 10-5 to 5.3 X 10-2 s-1 .
 It has been observed that there is a decrease in the flow stress, substantial increase in the
elongation and decrease in the elongation to failure at higher temperatures .
Fig 7:Comparison of nominal stress at different temperatures.

7. Literature survey (contd..):
7
2. Bolt et al, 2001 conducted study on warm deep drawing of AA1050, AA5754 and
AA6061alloys.
Parameters: Temperature range (100° C to 250° C)
 Warm forming increased the forming depth for all the cases; however, the benefits were
less significant for AA6016.
 Due to warm forming it was found out that there is no effect on post forming hardness
as compared to conventionally formed sheet.

8. Literature survey (contd..):
8
3. Li and Ghosh, 2003 performed uniaxial tests and deep drawing experiments on AA5182,
AA5754 and AA6111 alloys.
Parameters: Temperature range (25 – 350 °C)
Strain rate= 0.015-1.5 s-1.
 Warm forming did not cause a significant loss of post- forming yield strength.
 The warm formability, in terms of elongation, true fracture strain and m value of the
two strain hard enable alloy (AA5754 and AA5182+Mn) is superior to that of the
precipitation hard-enable alloy (AA6111-T4).

9. Literature survey (contd..):
9
4. Li and Ghosh,2004,
Parameter: Temperature range=200-350 °C and strain rate=1s-1
Boron nitride powder as a lubricant.
studied biaxial warm forming behaviour in the temperature range
200-350 °C and strain rate 1s-1.
 All the three alloy sheets exhibited improvement in their formability in the biaxial
warm forming at temperatures ranging from 200-350 °C.
Fig 8: Forming limit diagram of Al5182+Mn at high temperature.

10. Objectives:
The following are the objectives for the present work:
• To evaluate the constitutive properties of AA 5754 alloy at room temperature and elevated
temperature.
• To develop hemispherical cupping test for evaluating forming limit diagram at room
temperature and to evaluate FLD at room temperature.
• To develop experimental setup for evaluating forming limit diagram at elevated temperature.
• To study the forming behaviour of AA5754 sheet metal in terms of limiting dome height and
strain distribution.
10

11. Methodology:
 Applications and chemical composition of AA5754 alloy:
(http://www.azom.com/article.aspx?ArticleID=2863)
 Tensile test has been carried out at different temperatures (30 °C
to 250 °C) and different strain rate (10-3 and 10-1s-1).
11
Fig 11: Specimen used for tensile testing with the three directions shown.
Element Mn Fe Mg Si Al
%wt
present
0.50 0.40 2.60-3.30 0.40 balance
Fig9:Aluminium alloy used
helicopter
Fig 10: Car body

12. Methodology(contd..)
12
Where σ - true stress
K- Strength coefficient.
Ɛ- True strain
n- Strain hardening exponent.
0
0 0
ln( )
( ) ln( )
f
w w
t w l
f f
w
w
R
l w
l w
 
  
  
 
 After the tensile test, some of the equations were used to calculate the constitutive properties
mentioned below.
 Strain hardening behavior can be described by Hollomon equation.
 Plastic strain ratio (R) in three directions 0˚, 45˚ and 90˚ can be calculated by the given
formula:
Where, wf- final width, wo- initial width
lo- initial parallel length.
lf- final parallel length.
(1)
(2)
n
K 

13. Methodology (contd..)
13
 Strain rate sensitivity index (m) which gives information about the ductility of the material
can be calculated by the given power law:
(3)
Where, m is strain rate sensitivity index
n m
K  
 Hills 1948 yield criterion: Hill proposed an anisotropic yield criterion as a generalization of
the Huber-Mises-Hencky criterion.
Here f is the yield function; F, G, H, L, M & N are constants specific to the anisotropy
state of the material, and x, y, z is the principal anisotropy axes.
2 2 2 2 2 2
ij yy zz zz xx xx yy yz zx xy2 f(σ )= F(σ -σ ) +G(σ -σ ) +H(σ -σ ) +2Lσ +2Mσ +2Nσ =1
Fig 12: In Sheet Metal Forming Axis Orientation
 x is parallel to the rolling direction (RD) y in
transverse direction (TD) and z in the
normal direction.
(4)

14. Methodology (contd..)
14
 When the anisotropic orientation of the sheet metal coincides with the principal direction
of stress tensor then the Hill 1948 yield criterion has the form:
2 2 2
ij 2 3 3 1 1 22 f(σ )= F(σ -σ ) +G(σ -σ ) +H(σ -σ ) =1
Plastic strain increment is governed by flow rule as equation:
ij
ij
ij
f(σ )
d = dλ
σ
ε


Where, dλ is a positive scalar that depends on the stress increment.
For uniaxial tensile test in rolling direction,( 1 =σ σ and )2 3= = 0σ σ
0
2
3
H
r = =
G
d
d
ε
ε 90
1
3
H
r = =
F
d
d
ε
ε
Again from Eq. (5) we get for tensile test data:
(5)
(6)
(7)
2
(G+H)σ =1
Diving Eq. (5) by G and substituting Eq. (6) in (5) we get:
22 2 2
2 3 3 1 1 2
F H
G G G
(G+H)
(σ -σ ) +(σ -σ ) + (σ -σ ) = σ (8)
Substituting the values: 0
90
=
rF
G r
and 0=
H
r
G
we get:
20
0 0
90
2 2 2
2 3 3 1 1 2 (1+ )
r
r r
r
(σ -σ ) +(σ -σ ) + (σ -σ ) = σ (9)

15. Methodology (contd..)
15
 Development of toolings for stretch forming process:
Top die
Bottom die
Fig 13: Top and bottom die for stretch forming
process
Fig14: Hemispherical punch for stretch
forming process
 For punch, upper die and bottom die EN31Grade steel was used so that material can
withstand the load which occurs during the typical cupping test.

16. Methodology (contd..)
16
 Evaluation of FLD at room temperature: Forming limit diagram is a tool which gives
information about the formability of a Sheet metal.
• Preparation of samples and grid marking: Samples were cut by shearing and grid marking
was done by electrochemical etching method.
Power source
Electrode
Stencil
Etching solution
Fig 16: Setup for grid marking the samples with a power source, stencil and etching solution.
Fig 15: Dimensions of specimens for experimental determination of FLD.

17. Methodology (contd..)
17
 Strain measurement and evaluation of Forming limit diagram: The samples were
placed over bottom die which has a draw bead and the suitable blank holding force
(BHF) was applied and with the help of hemispherical punch specimens were deformed.
Fracture
Fig 17: Specimens deformed upto necking showing variation in the width. direction.
1
1
d d
e
d


2
2
d d
e
d


Where d1 is major diameter,d2
is minor diameter and d is
original diameter.
Fig 18: Leica microscope with a deformed specimen.

18. Methodology (contd..)
18
 A fracture occurred while doing the test with a specimen of width 20mm. To evade this
problem; a new Hasek specimen has been designed as shown in Fig.
R40
R50
100mm
Fig 19: Circular specimen designed by Hasek with grid circles.
Pressure
gauge
lever
Pressure
chamber
Top piece and
screws
Fig 20: Setup for bulge test with the deformed specimen.

19. Methodology (contd..)
19
360mm
Fig 21: AUTO CAD drawing and Image heating plate of EN 22 grade steel for heating
purpose.
 Warm forming setup:

20. Methodology (contd..)
20
Fig 22: Warm forming setup with insulation and heating plate

21. Methodology (contd..)
21
Insulations
Water jacket (for
heat regulation)
Control panel
Pump
Fig 23: Warm forming setup with insulation, heating plate and control panel.
 Photograph of Warm forming setup:

22. Results and discussion:
22
• Effect of temperature on stress-stain response:
Engineeringstress(MPa)
0
20
40
60
80
100
120
140
160
180
200
0 0.2 0.4 0.6 0.8 1
30°
C
At 0.001 s-1
175°C
200°C
250°C
Fig 24:Effect of temperature at a constant strain
rate on engineering stress- strain curve
Engineering strain
0
50
100
150
200
250
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
30°C
175°C
200°C
TruestressMPa True strain
At 0.001 s-1
Fig 25:Effect of temperature at a constant strain rate
on true stress- strain curve

23. Results and discussion(contd..):
23
0
50
100
150
200
250
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
250°C
0.001 s-1
250°C
0.1 s-1
30°C
0.1 s-1
30°C
0.001 s-1
True strain
TruestressMPa
• Effect of strain rate on stress-strain response:
Fig 26:Variation of true stress- strain curve with temperature and strain rate.

24. Results and discussion:
24
 Material properties of AA5754 alloy at elevated temperature:
Temperature(°C) K (MPa) n m R0 R45 R90
30 340.35 0.256 0.008 0.769 0.404 0.66
100 335.62 0.21 0.011 0.75 0.517 0.566
175 250.38 0.165 0.033 1.005 0.912 0.95
200 172.67 0.145 0.054 1.27 1.071 0.94
250 125.04 0.101 0.066 1.67 1.18 1.431

25. Results and discussion (contd..):
25
n(T) = -0.006T + 0.279
0
0.05
0.1
0.15
0.2
0.25
0.3
0 50 100 150 200 250 300
Temperature(°C)
K(T)= 4E-05T3 - 0.023T2 + 2.471T + 285.3
0
50
100
150
200
250
300
350
400
450
0 50 100 150 200 250 300
Temperature(°C)
StrengthcoefficientK,MPa
Strainhardeningexponent,nFig 27: Strain hardening exponent (n) of AA5754
as a function of temperature
Fig 28: Strength coefficient (K) of AA 5754 as a
function of temperature of temperature
 Effect of temperature on strength coefficient and strain hardening exponent:
n linearlyK polynomially
R² = 0.993
R² = 0.982

26. Results and discussion(contd..):
26
m(T) = 0.005e0.010T
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0 50 100 150 200 250 300
Temperature(°C)
Strainratesensitivityindex,m
Fig 29:Strain sensitivity index (m) of AA5754
as a function of temperature
 m value exponentially with temperature.
R² = 0.953
N. Abedrabbo et al. / International Journal of Plasticity 22 (2006)
314–341
Fig 30:Strain sensitivity index (m) of AA3003
as a function of temperature
 Effect of temperature on strain rate sensitivity index:

27. Results and discussion(contd..):
27
R45(T) = -2E-07T3 + 9E-05T2 - 0.007T + 0.541
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 50 100 150 200 250 300
Lankfordcoefficient,R45
Temperature(°C)
R90(T) = -2E-07T3 + 9E-05T2 - 0.007T + 0.541
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 50 100 150 200 250 300
Lankfordcoefficient,R90
Temperature(°C)
Fig 31: Planar anisotropy parameter R0 , R45 and R90 of AA5754 as a function of temperature.
R90 T
R45
T
R² = 0.998
R² = 0.967
R (T)= -2E-08T3 + 4E-05T2 - 0.005T + 0.890
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 50 100 150 200 250 300
Lankfordcoefficient,R0
Temperature(°C)
R² = 0.993
R0 T
 Effect of temperature on planar anisotropic property (R):

28. Results and discussion(contd..):
28
Fig 32: (a)Variation of yield locus with temperature and (b)Variation of yield locus with strain
rate.
30 °C
250 °C
10-3s-1
10-1s-1
• Variation of yield locus at different temperature and strain rate:
 Dip observed in the yield strength (from 96
Mpa to 75 Mpa).
 Increase in the yield strength from
96.32Mpa to147.44 Mpa.

29. Results and discussion(contd..):
29
• Forming limit diagram (FLD) at room temperature:
Fig 33: Forming limit diagram of (a) IF steel (b) AA5754-H22 and (c)
AA5182-O sheet of thickness 1mm.
Majorstrain(%)
Minor strain (%)
0
0.1
0.2
0.3
0.4
0.5
0.6
-0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
necked
safe
failed

30. • Forming limit diagram (FLD) at elevated temperature:
30
0
10
20
30
40
50
60
-30 -20 -10 0 10 20 30 40
(a)
(b)
(c)
(d)
Fig 34: Forming limit diagram of (a) AA5754-H22 at 30˚C, (b)AA5182-O
and (c) IF steel sheet of thickness 1mm (d) AA5754-H22 at 200 ̊C.
Results and discussion(contd..):
Majorstrain(%)
Minor strain (%)

31. Results and discussion(contd..):
31
• Strain distribution in deformed specimens at elevated temperature:
-10
-5
0
5
10
15
20
25
30
-40 -20 0 20 40
major strain
minor stain
(a) (b)
(c) (d)
Fig 35: Longitudinal strain distribution profile for AA5754 of thickness 1mm.
100x100mm2
lubricated condition
Distance from pole (mm)
Distance from pole (mm)
Distance from pole (mm)
Distance from pole (mm)
Strain(%)Strain(%)
Strain(%)
Strain(%)
100x100mm2 without
lubricated condition
100x40mm2100x20mm2
-20
-10
0
10
20
30
40
50
-40 -20 0 20 40
major strain at
30˚C
minor strain at
30˚C
major strain at
200˚C
minor strain at
200˚C
-10
0
10
20
30
40
50
60
-45 -25 -5 15 35
major strain at 30°C
minor strain at 30°C
major strain at
200°C
minor strain at
200°C
-5
0
5
10
15
20
25
30
35
40
45
-45 -25 -5 15 35
major strain
at 30°C
minor strain
at 30°C
major strain
at 200°C
minor strain
at 200°C

32. Results and discussion(contd..):
32
• Improvement in limiting dome height (LDH) at high temperature:
Dimension of the
specimen
Limiting dome
height(mm) at
30°C
Limiting dome
height(mm) at
200°C
% increase
100 x 20 mm2 13.26 17.49 31.90
100 x 40 mm2 15.935 17.58 10.32
100 x 60 mm2 13.437 16.70 24.28
100 x 80 mm2 13.86 18.55 33.83
100 x 100 mm2
Without lubricant
14.775 19.06 29.00
100 x 100 mm2
With lubricant
18.58 20.81 12.00
Bulge test 29.61
No heating
arrangement
for bulge test
No heating
arrangement
for bulge test
Fig 36: Limiting dome height (LDH) of biaxial
specimen at (a) 30 °C and (b) 200 °C.
 Dome height improved as the temperature
was increased from 30°C to 200°C.
14.775mm
19.06mm

33. Results and discussion(contd..):
33
 Failure Analysis: The elongation was measured at a temperature range of
30˚C -250˚C at different Strain rate
1 2 3 4 5
37.46mm
48.30mm
Fig 38: Specimens 1 to 5 showing effect of
increase in temperature.
10-1 s-1 and 10-3s-1.
ElongationT
TrueFracturestrain
m
Fig 39: True fracture strain vs. strain rate sensitivity
index(m).
0
0.1
0.2
0.3
0.4
0.5
0.6
0.008 0.011 0.033 0.054 0.066

34. Results and discussion(contd..)::
34
Dimple
Fig 40: Close view and an SEM image of fractured specimen at room temperature
 Fractography of specimen at 30 ˚C and 250˚C and 10-3 s-1:
 Large number of dimples were observed which clearly shows that the fracture is of
ductile fracture.
Dimple and
inclusion
 SEM image taken at 2000X magnification of the fractured specimen. Size

35. Results and discussion(contd..):
35
Fig 41: EDX test results.
 After conducting the Energy dispersive X ray spectroscopy test it was found out that
inclusion which was present may contain Al- Fe intermetallic compound.

36. Conclusions:
36
 Material is insensitive to the strain rate at room temperature (30°C) however it
became sensitive at high temperature (200°C).
 It is also observed that the post-uniform elongation increases due to increase in m-value
of the material.
 Formability is higher in tension-tension region compare to tension-compression region.
However the limiting strain of AA5754 is lower compared to conventional low carbon
steel sheets.
 The limiting dome height consistently increase during deformation at elevated
temperature for all specimens.
 In the strain distribution profile, it was observed that major and minor strain in case of
lubricated specimen was greater than in the unlubricated one.
 SEM fractography has shown the ductile fracture. And large number of voids has been
found out with inclusions present in them.

37. References :
37
[1] Amit Kumar Gupta, V.K. Anirudh, Swadesh Kumar Singh. Constitutive models to predict flow
stress in Austenitic Stainless Steel 316 at elevated temperatures. Materials and design 43(2013)
410-418.
[2] Nitin Kotkunde, Hansoge Nitin Krishnamurthy, Pavan Puranik, Amit Kumar Gupta, Swadesh
Kumar Singh. Microstructure study and constitutive modelling of Ti-6Al-4V alloy at elevated
temperatures. Materials and design 54(2014) 96-103.
[3] F. SHEHATA, M.J.PAINTER, R.PEARCE. Warm forming of aluminium/Magnesium alloy
sheet. Journal of Mechanical working technology 2(1978) 279-290.
[4] Y.C.Lin, Xiao-Min Chen, Ge Liu. A modified Johnson –Cook model for tensile behaviours of
typical high-strength alloy steel. Materials Science and Engineering A 527 (2010) 6980-6986.
[5] F. Ozturk, S.Toros, H.Pekel. Evaluation of tensile behaviour of 5754 aluminium –magnesium alloy
at cold and warm temperatures. Materials Science and Technology 7(2009) vol25 919-924.
[6] Daoming Li, Amit K. Ghosh. Biaxial warm forming behaviour of aluminium sheet alloys. Journal
of Materials Processing Technology 145 (2004) 281-293.

38. References :
38
[7] Daoming Li, Amit K. Ghosh. Tensile deformation behaviour of aluminium alloys at warm
forming temperatures. Materials Science and technology A352 (2003) 279-286.
[8]Nader Abedrabbo, Farhang Pourboghrat, John Carsley, Forming of aluminum alloys at
elevated temperatures – Part 1: Material characterization. International Journal of Plasticity
22 (2006) 314-341.
[9] P.J.Bolt, N.A.P.M Lamboo, P.J.C.M Rozier. Feasibility of warm drawing of aluminium
products. Journals of Materials Processing and Technology 115(2001) 118-121.
[10]P. Cavaliereet al. Hot and warm forming of 2618 aluminium alloy. Journal of Light Metals
2 (2002) 247–252

39. 39