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EFFECT OF EQUAL CHANNEL ANGULAR PRESSING ON
MICROSTRUCTURE AND MECHANICAL PROPERTIES ON NON
DENDRITIC LM25 ALUMINIUM ALLOY
This report is submitted in accordance with requirement of the University Teknikal
Malaysia Melaka (UTeM) for Bachelor Degree of Manufacturing Engineering
(Engineering Process) (Hons.)
by
NURHASYINAZ BT MOKHTAR
B051310232
940618-02-5542
FACULTY OF MANUFACTURING ENGINEERING
2017
Disahkan oleh:
_____________________________ ______________________________
Alamat Tetap: Cop Rasmi: Kg. Teluk. Mukim Binjal,_______ 06000 Jitra.___________________ Kedah._______________________
Tarikh: _______________________ Tarikh: _______________________ *Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai SULIT atau TERHAD.
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
Tajuk: EFFECT OF EQUAL CHANNEL ANGULAR PRESSING ON MICROSTRUCTURE AND MECHANICAL PROPERTIES ON NON DENDRITIC LM25 ALUMINIUM ALLOY Sesi Pengajian: 2016/2017 Semester 2 Saya NURHASYINAZ BINTI MOKHTAR (940618-02-5542) mengaku membenarkan Laporan Projek Sarjana Muda (PSM) ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut: 1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis. 3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan
pertukaran antara institusi pengajian tinggi. 4. *Sila tandakan (√)
(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysiasebagaimana yang termaktub dalam AKTA RAHSIA RASMI 1972)
(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/ badan di mana penyelidikan dijalankan)
SULIT
TERHAD
TIDAK TERHAD
DECLARATION
I hereby, declared this report entitled “Effect of Equal Channel Angular Pressing on
Microstructure and Mechanical Properties on Non Dendritic LM25 Aluminium Alloy” is the
results of my own research except as cited in references.
Signature :…………………………………………..
Author’s Name :NURHASYINAZ BINTI MOKHTAR
Date :22 June 2017
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of Universiti
Teknikal Malaysia Melaka as a partial fulfillment of the requirements for the degree of
Bachelor of Manufacturing Engineering (Manufacturing Process)(Hons.). The member of the
supervisory is as follow:
…………………..........
(Dr. Mohd Shukor bin Salleh)
i
ABSTRAK
Kajian ini adalah mengenai pemprosesan logam separa pepejal aloi aluminium
LM25 menggunakan penyejukan pemutus cerun diikuti oleh saluran sama sudut menekan.
Dalam kajian eksperimen ini, parameter yang paling berpengaruh di antara suhu tuangan dan
panjang penyejukan cerun yang memberi kesan globalisasi aloi LM25 semasa penyejukan
pemutus cerun telah dikaji. Selain itu, kekerasan, kekuatan tegangan dan tingkah laku patah
penyejukan pemutus cerun dan sampel pemutus konvensional telah disiasat. Semua kerja-kerja
eksperimen telah dilakukan dengan menggunakan sama aloi aluminium LM25. Aluminium
LM25 bilet aloi bahan mentah telah disediakan melalui teknik cerun penyejukan dan pemutus
konvensional yang telah dibuang terus ke dalam acuan. Beberapa sampel kemudiannya dirawat
dengan rawatan haba T6 iaitu rawatan penyelesaian 520 ° C selama 8 jam, penyejukan dalam
air, diikuti oleh penuaan pada 154 ° C selama 4 jam. Semua sampel kemudiannya diperhatikan
dengan menggunakan mikroskop optik (OM), Mikroskop Imbasan Elektron (SEM), kekerasan
dan ujian tegangan serta sifat-sifat patah. Keputusan mendedahkan bahawa pada mencurah
suhu 650 ° C dan 400 mm penyejukan panjang cerun, aloi LM25 yang mempamerkan ciri
mikrostruktur sfera kerana semua struktur dendrit telah diubah ke dalam ɑ-Al globul dan roset.
nilai kekerasan Vicker yang digambarkan bahawa sampel ECAP diproses dipertingkatkan
kekerasan tertinggi daripada pemutus konvensional dan penyejukan pemutus cerun. Di samping
itu, ia telah diperhatikan bahawa untuk kekuatan tegangan muktamad, sampel ECAP dengan
satu laluan sahaja yang 188,98 MPa mempunyai nilai tertinggi berbanding syarat lain dan
sampel as-tuang. Dalam semua penyiasatan dan ujian mekanikal, pemutus cerun penyejukan
yang menjalani T6 rawatan haba mendedahkan hasil yang jelas yang menjadi sifat-sifat yang
paling dominan dalam pengagihan mikrostruktur, kekerasan dan tegangan hartanah, berbeza
dengansampelbukanhabadirawat
ii
ABSTRACT
This study is about the semisolid metal processing of aluminium LM25 alloy using
cooling slope casting followed by equal channel angular pressing. In this experimental
study, the most influential parameters between the pouring temperature and the length of
cooling slope that affect the globalization of LM25 alloy during cooling slope casting were
studied. Besides, the hardness, tensile strength and fracture behavior of cooling slope
casting and conventional casting samples were investigated. All the experimental works
were accomplished by using same LM25 aluminium alloy. The aluminium LM25 alloy
feedstock billets were prepared through the cooling slope technique and conventional
casting that were cast directly into mould. Several of samples were then treated with a T6
heat treatment that is solution treatment 520°C for 8 hours, quenching in water,
followed by aging at 154°C for 4 hours. All of the samples were then observed by
u s i n g optical microscopy (OM), Scanning Electron Microscope (SEM), hardness and
tensile tests as well as fracture properties. The results revealed that at pouring temperature
of 650°C and 400 mm cooling slope length, the LM25 alloy exhibits the spherical
microstructural feature due to all dendritic structures were altered into ɑ-Al globule and
rosette. The Vicker’s hardness value depicted that ECAP processed sample enhanced the
highest hardness than conventional casting and cooling slope casting. In addition, it was
observed that for ultimate tensile strength, the sample of ECAP with one pass only which is
188.98 MPa has the highest value compared to other conditions and as-cast sample. In all
investigations and mechanical testing, the cooling slope casting that underwent T6 heat
treatment revealed the obvious results which became the most dominant properties in
microstructure distribution, hardness and tensile properties, in contrast with non-heat treated
sample.
iii
DEDICATION
I am dedicating this work to my beloved parents, Mokhtar bin Malid and Sopiah bt
Md. Isa, who always support and inspire me with their boundless love in achieving a
success in everything I do.
To my supervisor, Dr. Mohd Shukor bin Salleh, family and all my friends, without
them none of my success would be possible.
iv
ACKNOWLEDGEMENT
Alhamdulillah, all praise to Allah for His Grace and Blessings. First and foremost I
would like to express my gratitude to Allah S.W.T because of His love and strength that He
has given to me to complete my final year project. I do thank for His blessings to my daily
life, good health, healthy mind and good ideas especially during 10 months of the
completion of this project.
I would like to take this opportunity to extend my deepest gratitude to my supervisor,
Dr. Mohd Shukor bin Salleh for his excellent cooperation and supervised me in spite of
being extraordinarily busy with his daily duty. Thank you for all guidance, advices,
supports and the opportunity given for me to learn and endure the experience while
working on this project. Without his guidance and persistent help, this project would not be
possible.
In addition, I would like to give this appreciation to all assistant engineers and
lecturers in Faculty of Manufacturing Engineering (FKP) and Faculty of Engineering
Technology (FTK), UTeM for their sincere assistance and knowledge sharing regarding
this project.
Last but not least, I would like to thank to my beloved parents, family and all friends
for all of their moral support, prayers and encouragement that they gave to me during this
study.
v
TABLE OF CONTENT
Abstrak Abstract
i ii
Dedication
Acknowledgement
Table of Content
List of Tables
iii
iv v vi ix
List of Figures
List of Abbreviations
List of Symbols
x
xiii
xiv
CHAPTER 1: INTRODUCTION
1
1.1 Background of study 1
1.2 Problem statement 3
1.3 Objectives 4
1.4 Scope of study 4
1.5 Chapter overview 4
CHAPTER 2: LITERATURE REVIEW
6
2.1 Alloy (Aluminium) 6
2.1.1 Aluminium alloy 6
2.2 Semisolid Metal Processing (SSM) 9
2.2.1 Semisolid casting of aluminium alloy 2.2.2 Microstructure of Semisolid casting materials
9 11
2.3 Grain refinement 13
2.3.1 Grain refinement of Aluminium LM25 13
2.4 Cooling Slope Casting (CS) 15
2.5 Parameters of Cooling Slope Technique 17
vi
2.5.1 Angle of cooling Slope 2.5.2 Pouring temperature of molten metal 2.5.3 Cooling Slope length
17 18
19
vii
2.6 Equal Channel Angular Pressing 19 2.6.2 Grain refinement by ECAP 21 2.7 Parameters of Equal channel angular pressing 21 2.7.1 Number of passes 21 2.7.2 Type of routes 24 2.8 Tensile Testing 26
CHAPTER 3: METHODOLOGY 27
3.1 Gantt Chart of the Project 27
3.2 Flowchart of the Cooling Slope Casting and ECAP 29
3.3 Selection of Process Parameter 29
3.4 Experimental Procedures 30
3.4.1 Sample preparation 30
3.4.2 Feedstock production Using Cooling Slope Casting and Conventional
Casting Process 31
3.4.3 T6 Heat Treatment 33
3.5 Microstructure Investigation 34
3.5.1 Preparation of Samples for Morphology Investigation 34
3.5.2 Image Analysis 34
3.6 Hardness Testing 35
3.7 Tensile Testing 36
3.7.1 Preparation of tensile test samples 36
CHAPTER 4: RESULT AND DISCUSSION 38
4.1 Microstructure investigation 38
4.1.1 Cooling slope casting and conventional casting 38
4.1.2 Cooling slope casting and ECAP 39
4.1.3 T6 heat treatment 40
4.1.4 Shape factor and Globule size 42
4.2 Hardness testing 46
4.3 Tensile testing 48
4.4 Fracture Testing 51
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 54
5.1 Conclusion 54
viii
5.2 Recommendations 55
5.3 Sustainability Development 55
REFERENCES 57
APPENDICES
A Gantt Chart of FYP I 60
B Gantt Chart of FYP II 61
C Graph of Tensile Result for LM25 Aluminium Alloy 62
ix
LIST OF TABLES
2.1 Alloy chemical composition data of LM25 8
2.2 Thermophysical properties of LM25 aluminium alloy 9
2.3 Solid fraction of different slope angle 18
3.1 Gantt Chart for PSM 1 28
3.2 Parameters of cooling slope process for LM25 alloy 30
3.3 Composition of LM25 alloy specimen 31
4.1 The value of Vickers Hardness in as-cast, cooling slope and ECAP 46
samples
x
LIST OF FIGURES
2.1 Typical microstructure in semisolid metal 10
2.3a
2.3b
2.3c
Low magnification,
High magnification of dendritic microstructure by conventional casting
Globular microstructure by semisolid metal casting
12
2.4 Schematic illustration of cooling slope casting 16
2.5 Microstructure of Aluminium alloy processed by cooling slope 17
2.6 Hardness value versus passes of ECAP 22
2.7 Stress-strain curves of different number of ECAP passes 23
2.8 YS and UTS against number of passes 23
2.9
Schematic diagram for four fundamental type of routes
24
3.0 Values of Vickers hardness using route BC and C 25
3.1 Yield strength against number of ECAP passes 25
3.2 Example of tensile sample 26
3.3 Flowchart of cooling slope and ECAP process 29
3.4 Band saw machine 31
3.7 Set up apparatus for cooling slope 32
3.8 ECAP split die 33
3.9 T6 Heat Treatment 33
3.10 Sample preparation for microstructure investigation 34
xi
3.11 Rockwell hardness machine 36 4.0 Microstructure of LM25 aluminium alloy (a) as-cast at 650°C and 39
(b) cooling slope casting at 650°C and 400 mm length of slope
4.1 Microstructure of (a) cooling slope casting (b) equal channel angular
pressing of LM25 aluminium alloy 39
4.2 Microstructure investigation under OM (a) non-heat treated CS casting (b) heat
treated CS casting (c) non-heat treated ECAP (d) heat treated ECAP 41
4.3 SEM micrograph of CS casting which undergo (a) heat treatment process
and (b) non-heat treatment process 42
4.4 Variation of Shape factor for three different processes sample 43
xii
4.5 Comparison in the grain size (μm) of three sample types in different processes and non heat treated in cooling slope casting 44
4.6 Comparison of Non-heat treated and T6 heat treated sample in Cooling Slope casting and ECAP process 45
4.7 Comparison between non-heat treated and T6 heat treated fo CS casting and ECAP
45
4.8 The value of Vickers Hardness for Conventional casting and Cooling slope
casting 47
4.9 Variations of Vickers Hardness value for LM25 aluminium alloy of non-heat
treated and T6 heat treated for CS and ECAP samples
5.0 Sample that performed tensile test 49
5.1 Variation of Comparison of Ultimate Tensile Strength of As-cast, non-heat
treated CS, T6 heat treated CS, non-heat treated ECAP and T6 heat treated ECAP 49
5.2 The elongation to fracture of each type of LM25 alloy sample 50
5.3 SEM image for fracture testing in as-cast sample 51
5.4 SEM image for fracture testing in non-heat treated CS sample 51
5.5 SEM image for fracture testing in heat treated CS sample 52
5.6 SEM image for fracture testing in non-heat treated ECAP sample 52
5.7 SEM image for fracture testing in T6 heat treated ECAP sample
5.8 The metal scrap that is not used at cooling slope casting area 56
xiii
LIST OF ABBREVIATIONS
CNC - Computer Numerical Method
CS - Computer Slope
ECAP - Equal Channel Angular Pressing
EDM - Electrical Discharge Machine
FKP - Fakulti Kejuruteraan Pembuatan
FTK - Fakulti Teknologi Kejuruteraan
OM - Optical Microscopy
SEM - Scanning Electrone Microscope
SSM - Semisolid Metal
1
CHAPTER 1
INTRODUCTION
In introduction of Chapter 1, it will discuss and explain briefly about the background
of conducted study. From this chapter 1, the problem statement of study, research objective,
scope of study and chapter overview will be discussed.
1.1 Background of study
Equal channel angular pressing (ECAP) is a metal forming process that is well-known
used to improve the microstructure as well as the mechanical properties. This process is one
of an interesting technique because of its simple procedure. It also gives the metals that
ultrafine grained microstructure which can lead in increasing the mechanical properties. The
materials used for equal channel angular pressing is ranging from hardened alloys, pure
metals to precipitation, intermetallic and also metal matrix composites. Back to the early age
of 1980s, the equal channel angular pressing techniques was introduced by Segal. From the
method, the materials produced will be high-strength and also gives a very high strains into
bulk using of pure iron and pure copper. The effect of using ECAP method on the mechanical
behaviour has proven increase in the strength and hardness of the material. One of the success
way to increase the strength of metals is using severe plastic deformation (SPD) technique by
accumulating very large plastic strain without changing the area of cross section in
workpiece. During the equal channel angular pressing based severe plastic deformation
process, the cross section of workpiece retain same thus it can be process repeatedly until
2
achieved the required level of deformation. When the simple shear taking place in a thin layer
equal channels crossing plane, the deformation of billet will occur. Thus, with the high strain
and more fine grains of materials the behaviour of physical along with mechanical will be
improved.
In general principle of ECAP, basically the square or round cross section of billet is
crossed through is pressed through a rigid die. Then, the flow is forced to go through an
angled channel. The factor for a successive ECAP technique is that using the same outer
dimensions of billet in order to press for several times so that a high cumulative strains can be
achieved. Recently, this method is widely used and is well established. ECAP method is
utilized to enhance the characterization of metallic materials. The ultra-fine grained structure
of ECAP process have make them the most applied technique to obtain the high
performances level of some materials. In this regard, aluminium and its alloy are commonly
used in various application in industry such as in automotive and aircraft. Besides that,
aluminium alloy is also a light weight material. Over the last two decades Abd El Aal &
Sadawy (2015), materials with nanostructured and sub-microstructure have shown that an
improvement in their mechanical properties affected by ECAP method.
In order to produce products that having similarly or near net-shaped products,
specifically in automotive applications, semisolid metal (SSM) processing is the most
effective method for that reason. Semisolid metal process is chosen because of its advantages
over the conventional casting. Back to the few years before, the development of new alloys
and modified commercial alloys have turn to broad enthusiastically. Nowadays, this method
is used widely in manufacturing technology as an important role for producing engineering
stuffs. Semisolid processing is said to be capable in long-life die due to the reduced thermal
shock as well as reduce the macrosegregation.
Among all of the methods to produce semi-solid slurries including mechanical
vibration, mechanical stirring, new rheocasting process (NRP), twin screw reo-molding
process, narrow melt stream (NMS) and strain induced melt activation (SIMA), cooling slope
casting is the most preferable method. Cooling slope casting is one of the technique that is
3
simple and yet cost effective manner. In addition, a non-dendritic and globular microstructure
can be obtained through this cooling slope technique when it is heated at the range of semi-
solid.
Therefore, this present study is to analyse the microstructure on non-dendritic LM25
aluminium alloy by doing experimental test using cooling slope process and equal channel
angular pressing respectively. Thus, this study will be followed up by examined the effect of
ECAP on microstructure and mechanical behaviour of the alloy.
1.2 Problem Statement
According to the past study by Abd El Aal & Sadawy (2015) to produce the ultra-fine
grained (UFG) bulk pure aluminium it has be in increasing the number of passes by equal
channel angular pressing (ECAP) method. Based on his study, the sample are said to have
high misorientation angle, high mechanical properties and resistance to corrosion. While, in
the previous study Darban et al. (2016), the effect of equal channel angular pressing of Al-
7075 alloy on the fracture toughness is experimentally investigated by processing the ECAP
technique up to four passes but with the different routes used. Furthermore, the yield strength,
ultimate strength and microhardness depicted an improvement after four passes of ECAP.
Besides, the average grain size shown in transmission electron microscope (TEM) is
obviously refined from 40μm to less than about 500nm. There is less research that has been
carried out using this technique thus lack of information regarding the parameters that affect
the morphology of the sample and also the mechanical properties. This approach may give a
refine microstructure compared to other routes due to the high plastic strain rate undergone
by the specimen. It is important to know the effect of the process on the morphology and
mechanical properties. Regarding to this shortage, this project is conducted to visualize both
of microstructure and mechanical characteristics after the ECAP process. In addition, the
LM25 aluminium alloy was cast earlier by cooling slope method to produce a non-dendritic
microstructural specimen.
1.3 Research Objectives
4
Based on the stated problem above, this present study is conducted to achieve the
following objectives:
1. To produce the feedstock or billet by using cooling slope technique.
2. To investigate the microstructure behaviour of aluminium alloy after cooling slope
combined with equal channel angular pressing (ECAP).
3. To investigate the mechanical properties of LM25 aluminium alloy after ECAP
method.
1.4 Scope
This study is practically conducted to investigate on the microstructural properties and
also the mechanical behaviour of the ECAPed specimen. The ECAPed specimen is then
examined using Vickers hardness tester. In this work, the aluminium LM25 alloy is chosen as
the workpiece. Subsequently, the reason that affects the microstructural properties on non-
dendritic LM25 aluminium alloy will be identified.
1.5 Chapter Overview
For the overview in chapter one, it contains the background of study and also the
problem statement of project. Apart from that, the research objectives, the study scope and
chapter overview are also included. The important objectives of this study is being
highlighted earlier as to produce the feedstock or billet by using cooling slope method in
order to get the globular or non-dendritic microstructure properties. The mechanical
properties is also have to be investigated just after the equal channel angular pressing method
in order to know the improvement on the specimen properties. Next, during this study there
are only two main priotities that have being construct on the test specimen which is the
5
microstructure and mechanical properties by using equal channel angular pressing machine.
In chapter two, it explain about the literature review of project. The purpose of the review is
to assist the discussion and also the methodology of study. Lots of journals and other legal
resources is searched and being studied in detail so that the information and knowledge about
the project is accurate. The apparatus and method used within this study is consist in chapter
three. While in chapter four, the result and data obtained throughout the project has been
discussed and applied. Lastly, the overall of the study has been conclude in chapter five along
with the recommendations for the future improvement.
6
CHAPTER 2
LITERATURE REVIEW
The chapter of this literature review on effect of equal channel angular pressing on
microstructure and mechanical properties on non-dendritic LM25 aluminium alloy that is
widely used in industry of manufacturing to produce smaller grain size of material.
Furthermore, this chapter will begin on the semisolid metal processing review of aluminium
alloy. Apart from that, the LM25 aluminium alloy that is preferred to use in this study is also
assisted in this chapter.
2.1 Alloy (Aluminium)
2.1.1 LM25 Aluminium Alloy
Aluminium-Magnesium-Silicon alloy or LM25 aluminium alloy is one of the
aluminium material that is widely used by industry especially automotive industry.
Nowadays, automotive industry has dominated the aluminium casting with two thirds of all
aluminium castings. Aluminium casting is said to grow continually at the expense of iron
castings because the uses of aluminium has become important in some industry. Despite of its
cost that is obviously expensive than ferrous castings, the requirement of its characteristics as