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MECHANICAL PROPERTIES OF DISSIMILAR ALUMINUM-BASED ALLOY JOINTS BY MIG WELDING
AHMAD DANIAL BIN ABDULLAH
Report submitted in partial fulfillment of the requirementsfor the award of the degree of
Bachelor of Mechanical Engineering with Mechanical Engineering
Faculty of Mechanical EngineeringUNIVERSITI MALAYSIA PAHANG
JUNE 2012
vi
ABSTRACT
This thesis deals with the investigation of microstructure and mechanical properties of weld joint of AA5052-H32 and AA6061-T6 aluminum alloys by using MIG welding process. The objective of this thesis is to investigate the effect of parameters to the mechanical properties and microstructure of AA5052-H32 and AA6061-T6. The thesis describes the proper MIG welding process using automatic table in order to investigate the effect on microstructure and mechanical properties of weld joint of AA5052-H32 and AA6061-T6. The aluminum ER5356 was used as filler in this experiment. The studies of mechanical properties that are involved in this thesis consist of toughness, tensile strength of AA5052-H32 and AA6061-T6 weld joint before and after MIG welding process. Four different parameters were used in order to determine the correlation between mechanical properties and microstructure of the weld joint. As aresult, it is observed that the current is the parameter which has the highest influence to the UTS and toughness and it is followed by torch angle, speed and lastly weld passes.The optimum parameter for the highest value of UTS and toughness is found; current=90A, torch angle=+15, speed=4mm/s and weld pass=1. The microstructure shows crack sensitivity and porosity which decreases the strength and toughness of weld joint. As for the recommendation, the other properties including hardness, corrosion resistance should be considered in order to optimally select a material for its specific application.
vii
ABSTRAK
Tesis ini membentangkan penyelidikan mikrostruktur dan ciri-ciri mekanikal logam kimpalan aluminium AA5052-H32 dan aluminium AA6061-T6 dengan menggunakan proses MIG welding. Objektif tesis ini ialah mengkaji kesan setiap parameter yang berlainan ke atas mikrostruktur dan ciri-ciri mekanikal logam kimpalan yang menggabungkan aluminium AA5052-H32 dan AA6061-T6. Selain itu, tesis ini juga menerangkan proses MIG welding yang betul dengan menggunakan meja automatikbagi menghasilkan logam kimpalan yang berkualiti. Antara skopnya ialah logam isianER5356 digunakan untuk memastikan gabungan yang baik terhasil antara kedua-dua aluminium. Antara spesifikasi projek ini adalah merangkumi ciri-ciri mekanikal yang terdiri daripada kekerasan dan kekuatan tensil. Oleh yang demikian , empat jenis parameter proses telah ditetapkan bagi mengkaji dan memenuhi spesifikasi projek ini. Keputusan yang diperoleh membuktikan bahawa parameter yang berbeza mampu mempengaruhi cirri-ciri mekanikal dan mikrostruktur logam kimpalan tersebut. Dalam kajian dari segi mikrostrukturnya, ia membuktikan bahawa kehadiran kesan keretakan dan ruang-ruang udara member kesan ke atas kekuatan tensil dan kekerasan logam kimpalan yang terhasil. Secara konklusinya, kita perlu menjalankan kajian ke atas ciri mekanikal yang lain seperti ketahanan daripada karat dan kekuatan dimana ia dapat dihasilkan dalam kombinasi terbaik untuk kegunaan bidang kejuruteraan.
viii
TABLE OF CONTENTS
Page
SUPERVISOR’S DECLARATION ii
STUDENT’S DECLARATION iii
DEDICATION iv
ACKNOWLEDGEMENTS v
ABSTRACT vi
ABSTRAK vii
TABLE OF CONTENTS viii
LIST OF TABLES xi
LIST OF FIGURES xiii
LIST OF ABBREVIATION xvi
CHAPTER 1 INTRODUCTION
1.1 Background Studies 1
1.2 Problem Statements 2
1.3 Project Objectives 3
1.4 Project Scopes 3
1.5 Overview of Report 3
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction 4
2.2 Aluminum Alloys 4
2.2.1 Types of Aluminum Alloys 52.2.2 Intermetallic Compound (IMC) 7
2.2.3 Aluminum AA6061-T6 and AA5052-H32 9
2.3 MIG Welding Process 13
2.3.1 Equipment 14 2.3.2 Welding Gun 16 2.3.3 Power Supply 16
2.3.4 Electrode 172.3.5 Shielding gas 17
ix
2.3.6 Operation 17
2.4 Mechanical Testing 18
2.4.1 Charpy Test 18 2.4.2 Tensile Test 20
2.5 Taguchi Approach 21
CHAPTER 3 METHODOLOGY
3.1 Introduction 24
3.2 Flow Chart 25
3.3 Flow Chart Description 26
3.3.1 Design Selection 26
3.3.2 Preparation of Specimen 30
3.3.3 Preparation of Welds 30
3.3.4 Welding Process 30
3.3.5 Polishing Process 31
3.3.6 Optical Investigation 33
3.3.7 Mechanical Testing 34
3.3.8 Analysis of Experimental Data 36
CHAPTER 4 RESULTS AND DISCUSSION
4.1 Introduction 39
4.2 Mechanical Properties 39
4.2.1 Tensile Strength 40 4.2.2 Charpy Toughness 43 4.2.3 Effect of Speed,Torch Angle Current, 43
Weld Pass to UTS and Toughness
4.3 Taguchi Method 47
4.3.1 ANOVA 47 4.3.2 Main Effect Plot 49 4.3.3 Regression Analysis 50 4.3.4 Contour Plot and Surface Plot for Charpy Toughness 53 4.3.5 Contour Plot and Surface Plot for UTS 57 4.3.6 Experimental Data and Predicted Data Comparison 60
4.4 Microstructure Observation 63
x
4.4.1 Microstructure 63 4.4.1 Defect in Weld Joint 66
CHAPTER 5 CONCLUSION AND RECOMMENDATIONS
5.1 Introduction 69
5.2 Conclusions 69
5.3 Future Recommendations 70
REFERENCES 71
APPENDICES 73
A Gant Chart
xi
LIST OF TABLES
Table No. Title Page
2.1 Aluminium alloys in space frame car design in Europe and North America
5
2.2 Classification of aluminum alloys 6
2.3 Microstructure of AA6061-T6 and AA5052-H32 -11 10
2.4 Composition of AA5052-H32 and AA6061-T6-12 11
2.5 Mechanical Properties of AA5052-H32 and AA6061-T6 -13 11
2.6 Properties of AA5052-H32 and AA6061-T6 -14 12
2.7 Example of process parameter: Injection moulding parameters and their levels
21
2.8 Experimental plan using L9 orthogonal array 22
2.9 Example of ANOVA: ANOVA table for bending test 24
3.1 Welding Test Result 27
3.2 Parameter of Experiment 28
3.3 Design of experiment using Taguchi Method by using Mixed Level Design – L18 (2 levels 1 columns + 3 levels 3 column)
28
3.4 Analysis of Variance (ANOVA) of UTS vs Speed; Welding pass; Current; Torch angle
38
4.1 Mechanical Properties of AA6061-T6 and AA5052-H32 Weld Metal (weld joint)
40
4.2 ANOVA 48
4.3 Rank of every parameter based on the Taguchi Analysis;Combination of UTS & Toughness vs Speed; Welding pass; Current; Torch angle
48
4.4 Comparison of results with mean predicted value 51
4.5 Factor levels for predictions based on Taguchi Method 51
xii
4.6 Predicted values of S/N ratio, Mean and Standard Deviation based Taguchi Method
52
4.7 Predicted Data versus Experimental Data 60
xiii
LIST OF FIGURES
Figure No. Title Page
2.1 The eutectic particles of 6082 alloy 8
2.2 Eutectic region of aluminum 6XXX 8
2.3 Eutectic region in 5XXX 9
2.4 Phase diagram of Aluminum 5XXX 13
2.5 Phase diagram of 6XXX 13
2.6 MIG Circuit diagram 14
2.7 GMAW torch nozzle cutaway image 15
2.8 GMAW weld area 18
2.9 Charpy test 19
2.10 Stress-strain curve 20
2.11 Example for main effect graph 22
3.1 Process flow chart of study 25
3.2 (a) Weld specimen for Charpy’s Test, (b) Weld specimen for
Tensile Test
29
3.3 a) Aluminum AA5052-H32 and b) AA6061-T6 sheet 30
3.4 a) Power supply, b) Automatic Working Table 31
3.5 Polisher-grinder Meserv for various size 32
3.6 Optical Microscope 33
3.7 a) Charpy’s Test machine, b) Swinging Pendulum 34
3.8 Charpy Test Specimen 34
3.9 Tensile Test Machine 35
3.10 Specimen of Tensile Test (ASTM E8M-04) -43 35
xiv
4.1 Graph UTS value versus experiment number 40
4.2 Graph Stress versus Strain; a) Exp. 1 for minimum UTS, b) Exp.
9 for medium UTS, c) Exp. 6 for maximum UTS
42
4.3 Charpy value versus experiment number 43
4.4 Weld toe angle 45
4.5 weld toe of specimen: a) Experiment 1, b) Experiment 6 and c)
Experiment of optimize value parameter
46
4.6 Double weld passes of experiment 14 specimen 47
4.7 Graph of Main Effect Plot for S/N Ratio 49
4.8 Main Effect Plot for Mean 50
4.9 Crack Profile of tensile specimen based on optimum parameter 52
4.10 Crack Profile of Charpy’s test specimen based on the optimum
parameter
53
4.11 (a) contour plot: Charpy’s toughness vs current; speed, (b)
surface plot: Charpy’s toughness vs current; speed
54
4.12 (a) contour plot: Charpy’s toughness vs current; torch angle, (b)
surface plot: Charpy’s toughness vs current; torch angle
55
4.13 (a) contour plot: Charpy’s toughness vs torch angle; speed, (b)
surface plot: Charpy’s toughness vs torch angle; speed
56
4.14 (a) contour plot: UTS vs current; speed, (b) surface plot: UTS vs
current; speed
57
4.15 (a) contour plot: UTS vs torch angle; current, (b) surface plot:
UTS vs torch angle; current
58
4.16 (a) contour plot: UTS vs torch angle, speed, (b) surface plot: 59
xv
UTS vs torch angle; speed
4.17 Experimental UTS versus predicted UTS 61
4.18 Experimental charpy toughness versus predicted charpy
toughness
62
4.19 Microstructure of; a) AA5052-H32 microstructure, b) AA6061-
T6 microstructure by magnification of 50X.
63
4.20 Porosity in Weld metal (WM) microstructure 64
4.21 Heat affected zone (HAZ) and fusion zone (FZ) in
Microstructure
65
4.22 Fusion zone of 6061 welds 66
4.23 Porosity in weld metal zone of 6061 welds 67
4.24 Crack sensitivity in weld joint of 6061 microstructure 68
xvi
LIST OF ABBREVIATIONS
AA Aluminum alloy sheet
T6 A type of heat treatment process
H32 A type of hardening process
ASTM American Society for Testing and Materials
MIG Metal inert gas
TIG Tungsten inert gas
DOE Design of experiment
UTS Ultimate tensile strength
CTE Coefficient thermal expansion
AC Alternating current
DC Direct current
SMAW Shielded metal arc welding
DF Degree of freedom
SM Sum of squares
MS Mean square
F F-function
SSR Sum of square regression
SSE Sum of square error
SST Sum of square total
1
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND
This thesis is about the investigation of weld joint (dissimilar Aluminum alloys)
microstructures and mechanical properties using MIG welding process. Aluminum is
the second important after steel usage because of its characteristic which is high
strength stiffness to weight ratio, good corrosion resistance, good formability better
conductor of heat and electricity. It has been the best candidate to replace heavier
material like steel and copper in automobile because it has the recycling potential. The
choice of material is influenced by the requirement to improve the economy of fuel and
also the energy consumption.
For example, automotive companies have been given mandate by US
Government that they need to minimize vehicle exhaust emission, enhance fuel
economy and improve occupant safety (W.S. Miller, 2000). In automotive industry,
welding of dissimilar parts of different weld will be much needed because each part
(inner and outer panel consist of different aluminum alloys) of car needs to be joined
together. The increasing of aluminum and magnesium alloys is mainly caused by the
rapid growth of application of material that has the light weight characteristic (D.-
A.Wang, 2007). And for this study, MIG (metal inert gas) welding process is chosen to
join the welds.The material that will be used is Aluminum alloy AA5052-H32 series
and 6061-T6 series for the experiment because they are often used in the industry (W.S.
Miller, 2000). While the microstructure and mechanical properties investigation consists
of tensile strength, toughness and corrosion resistance of the weld before welding
process and weld metal (WM) after MIG welding process.
2
1.2 PROBLEM STATEMENT
Aluminum alloys may often be used to replace steel in many applications
especially in automotive industry welding process (W.S. Miller, 2000). But, the
problem is the high difference of thermal conductivity of different aluminum alloys
using MIG or TIG will cause problems (Luijendijk, 2000). The lack of fusion of
material or excessive melting of material that has lower thermal conductivity is caused
by the larger thermal conductivity in arc that flow in material. The other problem in
MIG welding between dissimilar weld relates to the transition zone between the metals
and the intermetallic compounds (IMC) that produced in this transition zone.
It is very important to investigate the phase diagram of the two metals for the
fusion type welding process like MIG welding process. The dissimilar joints only can
be made successfully if there is mutual solubility exist between both aluminum alloys.
No solubility between the aluminum alloys can give the problem to the joint process.
The intermetallic compound formed between dissimilar weld need to be investigated to
check their crack sensitivity, ductility and susceptibility to corrosion, etc. The
microstructure views need to be done observe the eutectic phase in the intermetallic
compound.
The other factor causes problem to the welding of dissimilar aluminum alloys
relates to the thermal coefficient of thermal expansion (CTE) of both welds (Luijendijk,
2000). The widely difference between both thermal coefficient of thermal expansion
can cause the internal stresses set up in the IMC zone during any temperature change of
the welding process. The service failure may soon occur if there is extreme brittleness
characteristic in intermetallic zone. The last factor is melting temperatures of the two
aluminum alloys (Luijendijk, 2000). If there are differences in melting point, it will
cause the other problem. This is of primary interest when a welding process utilizing
heat is involved since one metal will be molten long before the other when subjected to
the same heat source. The high heat input of welding will make the weld has advantage
when welds of different melting temperature and thermal expansion to be joined.
3
1.3 OBJECTIVES
The objectives of this project are:
1) To investigate the effect of parameters; torch angles, speeds, welding passes and
currents to the mechanical properties of weld joints.
2) To predict the optimum parameters based on Taguchi methods analysis and
verified with experimental
3) To study the different of mechanical properties and microstructure of weld joint
(AA5052-H32 and 6061-T6 aluminum alloys) using the different welding
parameters.
1.4 SCOPE OF PROJECT
The scopes of the project are:
1) Welding process of different Aluminum alloys
2) Tensile and impact test investigation
3) Microstructure Analysis of weld joint (weld metal)
1.5 OVERVIEW OF REPORT
Chapter 1 mainly briefs about the background of the project which involves the
introduction, problem statements, objectives and scopes of the report. Chapter 2
basically describes more about the studies on microstructure, mechanical properties of
aluminum alloy which has been done earlier by other scientists and engineers and
Taguchi Method. Whereas Chapter 3 introduces the experimental procedure utilized to
characterize the aluminum alloys studies the step by step process that will be done
during this project and steps to perform Taguchi analysis with experimental values.
Chapter 4 mainly discuss about the results obtained during the experiment. Lastly,
Chapter 5 discuss about the conclusions that can be derived from this report and suggest
few future recommendations.
4
CHAPTER 2
LITERATURE REVIEW
2.1 INTRODUCTION
In this chapter, it basically describes more about the studies on microstructure
and mechanical properties of aluminum alloys which has been done earlier by other
scientists and engineers. Therefore, it also discussed about the MIG welding process
which has been used in this experiment.
2.2 ALUMINUM ALLOYS
The typical alloying elements usually consist of copper, magnesium, manganese,
silicon, zinc, etc. Aluminum alloy is classified into two principal namely casting alloys
and wrought alloys that consist of the heat-treatable and non-heat-treatable. About 85%
of aluminum used for wrought products. For example is foils, rolled plate and foils.
Aluminum alloys are mainly used in the components and engineering structures
that required the light weight and high corrosion resistance of material. Alloys
composed of aluminum and magnesium have been used widely in aerospace
manufacturing because of light weight features. Aluminum 5xxx is lighter than other
aluminum alloys. It also less flammable than aluminum alloys that contained high
percentage of magnesium. Outstanding bare metal corrosion of the 5xxx and 6xxx
aluminum materials is the obvious and significance difference between aluminum and
steel (W.S. Miller 2000). Table 2.1 shows the applications of aluminum 5xxx and 6xxx
in automotive industries.
5
Table 2.1: Aluminium alloys in space frame car design in Europe and North America,
Parts Europe North AmericaOuter Panels 6061-T4 6111-T4
Inner Panels 5051/5182/6181A 6111/2008/5182
Structure/Sheet 6XXX-T4 5754-O
Structure/Extrusion 6XXX 6XXX
Source: W.S. Miller (2000)
2.2.1 Types of Aluminum Alloys
There are many types of aluminum alloys. It consists of heat treatable and non-
treatable aluminum alloys. Table 2.2 shows the types of aluminum alloys and its
classification.
6
Table 2.2: Classification of aluminum alloys
Series Properties1xxx It contains 99% of Aluminum Non-heat treatable
2xxx Aluminum Copper approximation 2 -10%. Strength and allows precipitation hardening. Weld solidification crackingcan occurs.
Heat treatable
3xxx Aluminum Manganese. It increasesstrength.
Non-heat treatable
4xxx Aluminum Silicon. It can reduce meltingtemperature and can be heat treated alloy when combined with magnesium.
Both heat treatable and none-heat
treatable
5xxx Aluminum Magnesium. It increases strength.
None-heat treatable
6xxx Aluminum Magnesium plus Silicon. It creates a unique compound magnesium silicide Mg2Si and suitable for extrusion components. It has heat treat properties.
Heat treatable
7xxx Aluminum Zinc. It provides a heat treatable aluminum alloy which has very high strength when zinc copper and magnesium is added. Stresscorrosion cracking and some alloys can be weld using MIG and some cannot.
Heat treatable
Source: Electric, L (2009)
a) None Heat Treatable Aluminum Alloys
Cold working or strain hardening process can increase strength of this type of
aluminum alloys. Mechanical deformation will occur in the aluminum structure in order
to reach the desired strength and it will cause the increasing of resistance to strain
producing both higher and lower ductility. Non-heat treatable alloys cannot get high
strength characteristics of heat treatable precipitation-hardened alloys. The absence of
precipitate-forming elements in the low-to-moderate strength becomes beneficial for a
welding perspective. This is because many of alloy additions needed for heat treatable
precipitation hardening, magnesium plus silicon or copper plus magnesium can lead to
hot cracking during solidification in welding process.
7
b) Heat treatable aluminum alloys
Different from non-heat treatable alloys, heat treatable aluminum alloy achieve
their optimum mechanical properties by thermal controlled heat treatment. The 2xxx,
6xxx and 7xxx series are heat treatable aluminum alloys where 4xxx series consist of
heat treatable and non-heat treatable alloys. It tends to undergo hot cracking. Heat
treatable alloys get their mechanical properties by solution heat treatment, thermal
treatment and artificial aging are the most common methods.
2.2.2 Intermetallic Compound (IMC)
Intermetallic compound in aluminum AA5052-H32 and AA6061-T6 need to be
observed before the experiment is performed. For example for this observation,
aluminum 6082 is chosen to be example for this study (G. Mrowka-Nowotnlk, 2007).
There are three types of eutectic particles in the intermetallic compounds that is consist
of α, β and the Mg2Si as shown in the Figure 2.1(a) and 2.1(b).
(a)
8
Figure 2.1: The eutectic particles of 6082 alloy in: a) ternary eutectic, b) the quaternary
eutectic
Source: G. Mrowka-Nowotnlk 2007
Mg2Si appeared in this microstructure view of 6082 because Si is the important
element in the aluminum 6xxx as AA6061-T6. This is shown in Figure 2.2.
Figure 2.2: Eutectic region of aluminum 6xxx
Source: Donald R. Askeland 2002
(b)
9
The Mg2Si possibly not appear in the aluminum 5xxx series as AA5052-H32
because Si is not the major element. This is shown in Figure 2.3.
Figure 2.3: Eutectic region in 5xxx
Source: Donald R. Askeland 2002
2.2.3 Aluminum AA6061-T6 and AA5052-H32
There are a few things that must be reviewed in both aluminums which is
chemical composition, mechanical properties, thermal properties, etc. This is to make
sure the factor that will give the problem to the welding process of both materials.
2.2.3.1 Composition of AA6061-T6 and AA5052-H32
The microstructure of the aluminum AA6061-T6 and AA5052-H32 is shown in
the Table 2.3. It seems that there is a difference in the grain size of both alloys. The
grain size may be one of a factor that can be considered can affect the mechanical
properties of aluminum alloys.
10
Table 2.3: Microstructure of AA6061-T6 and AA5052-H32
Aluminum Alloys
Micrograph (room temp.)
AA5052-H32
AA6061-T6
Source: S. Mahabunphachai (2010)
The composition of both alloys is shown in the Table 2.4. ER5356 filler
composition also put in the table to compare its composition with both AA5052-H32
and AA6061-T6. As mentioned before (refer to Table 2.2), the AA5052-H32 has more
magnesium composition than AA6061-T6. But the ER5356 contains highest
magnesium composition compared to both alloys. AA6061-T6 has the highest
composition of Silicon compared to AA5052-H32 and ER5356. The composition of
both aluminums also must be considered to make sure that the continuity can be success
in the weld materials.
11
Table 2.4: Composition of AA5052-H32 and AA6061-T6
Alloys Elements and weight percentage (wt%)Al Cr Cu Fe Mg Mn Si Ti Zn Be Other
AA5052-H32
95.7 -97.7
0.15 -0.35
Max 0.1
Max 0.4
2.2-2.8
Max 0.1
Max 0.25
- Max 0.1
- Max 0.15
AA6061-T6
95.8-98.6
0.04-0.35
0.15-0.4
Max 0.7
0.8-1.2
Max 0.15
0.4-0.8
Max 0.15
Max 0.25
- Max 0.15
ER 5356 92.9 -95.3
0.05 -0.2
0.1 0.4 4.5-5.5
0.05- 0.2
Max0.25
0.06-0.2
Max 0.1
Max 0.000
8
Max 0.15
Source: Metal Handbook 10th (1990)
The ultimate tensile strength (UTS) of AA6061-T6 is higher than AA5052-H32.
This can be seen in the Table 2.5. The table shows the other mechanical properties like
hardness, fatigue strength of AA5052-H32, AA6061-T6 and also the filler used in this
welding.
Table 2.5: Mechanical Properties of AA5052-H32 and AA6061-T6
Mechanical Properties AA6061-T6 AA5052-H32
Filler 5356
Hardness, Brinell 95 60 -Hardness, Vickers 107 83 -Tensile Strength, Ultimate (MPa) 310 228 -Tensile Strength, Yield (MPa) 276 193 -Modulus of Elasticity (GPa) 68.9 70.3 70Poissons Ratio 0.330 0.330 0.330Fatigue Strength (MPa) 96.5 117 -Machinability 50% 30% -Shear Modulus (GPa) 26.0 25.9 26Shear Strength (MPa) 207 138 -
Source: Metal Handbook 10th (1990)
The other important mechanical property that must be considered is melting
point because it will cause the problem to the weld dilution if the both weld has the big
difference in boiling point. It seems like there is no big difference between AA5052-
H32 and AA6061-T6 in boiling point as shown in the Table 2.6. This means that the
12
joining process of these two different welds can be successful because they will melt at
the almost same temperature. The CTE values are also not very different in both
materials as shown in the table. The thermal stress will not be the problem to welding
process in this study.
Table 2.6: Thermal Properties of AA5052-H32 and AA6061-T6
Thermal Properties AA6061-T6 AA5052-H32 ER 5356
CTE, linear (µm/m-°C) 23.6 @Temperature 20.0 - 100 °C
23.8 µm/m-°C@Temperature 20.0 - 100 °C
24.1 µm/m-°C@Temperature 20.0 - 100 °C
Specific Heat Capacity (J/g-°C)
0.896 0.880 0.904
Thermal Conductivity (W/m-K)
167 138 116
Melting Point (°C) 582 - 651.7 607.2-649 571-635Solidus (°C) 582 607.2 571Liquidus (°C) 651.7 649 635
Source: Metal Handbook 10th (1990)
2.2.3.2 Phase diagram of AA5052-H32 and AA6061-T6
Figure 2.4 shows the phase diagram of aluminum 5xxx series and the eutectic
particles α, β and (α + β) in the aluminum 5xxx series. Figure 2.5 shows the eutectic
region in the aluminum 6xxx series and the eutectic particles α, β and (α + β) in the
aluminum 6xxx series.