study on equal channel angular extrusion of circular cross section components and its application

180 Pages·2016·3.36 MB·English

STUDY ON EQUAL CHANNEL ANGULAR
EXTRUSION OF CIRCULAR CROSS SECTION
COMPONENTS AND ITS APPLICATION FOR

JOINING DISSIMILAR METALS

DAVOUD MASHHADI JAFARLOU

FACULTY OF ENGINEERING
UNIVERSITY OF MALAYA
KUALA LUMPUR

2016
STUDY ON EQUAL CHANNEL ANGULAR EXTRUSION OF
CIRCULAR CROSS SECTION COMPONENTS AND ITS
APPLICATION FOR JOINING DISSIMILAR METALS

DAVOUD MASHHADI JAFARLOU

THESIS SUBMITTED IN FULFILMENTOF THE
REQUIREMENTS FOR THE DEGREE OF DOCTOR OF
PHILOSOPHY

FACULTY OF ENGINEERING
UNIVERSITY OF MALAYA
KUALA LUMPUR

2016
UNIVERSITY OF MALAYA
ORIGINAL LITERARY WORK DECLARATION

Name of Candidate: Davoud Mashhadi Jafarlou (I.C/Passport No: H95659360)
Matric No: KHA130066
Name of Degree: Doctor of Philosophy (PhD)
Title of Thesis: Study on equal channel angular extrusion of circular cross
section components and its application for joining dissimilar metals

Field of Study: Engineering Design

I do solemnly and sincerely declare that:
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dealing and for permitted purposes and any excerpt or extract from, or
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expressly and sufficiently and the title of the Work and its authorship have
been acknowledged in this Work;
(4) I do not have any actual knowledge nor do I ought reasonably to know that
the making of this work constitutes an infringement of any copyright work;
(5) I hereby assign all and every rights in the copyright to this Work to the
University of Malaya (“UM”), who henceforth shall be owner of the
copyright in this Work and that any reproduction or use in any form or by any
means whatsoever is prohibited without the written consent of UM having
been first had and obtained;
(6) I am fully aware that if in the course of making this Work I have infringed
any copyright whether intentionally or otherwise, I may be subject to legal
action or any other action as may be determined by UM.

Candidate’s Signature Date:

Subscribed and solemnly declared before,

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Name:
Designation:
ABSTRACT
In the last two decades, significant focus has been directed toward severe plastic
deformation (SPD) as a direct method to produce bulk metals with superior mechanical
properties. Numerous researches have been conducted in order to develop SPD methods
for grain refinement of metallic structure with various geometrical shapes and chemical
compositions. Among these methods, equal channel angular extrusion (ECAE) is the
most developed SPD technique due to its capability of processing structural components.
The mechanical properties of wide range of pure metals and alloys have been
investigated in different research works; however there is a lack of study on mechanical
properties of AA 6063 processed by ECAE. Moreover the ECAE technique is used
mostly for grain refinement of components with circular (rod) or rectangular (beam)
cross sections and there is no robust study on developing this technique for the
processing of tubular components. Therefore, the current study focused on developing
ECAE for processing tubular components. Additionally, in this research a developed
method for solid state joining of dissimilar metals was proposed.
In the first phase of this study, the mechanical properties of ECAE treated AA 6063
were investigated. Following the ECAE process, samples were subjected to heat
treatment (HT), hard anodizing (HA), and a combination of HT and HA. From the
experimental fatigue and fretting fatigue tests, it was apparent that the ECAE treatment
improves fatigue and fretting fatigue lives of the samples at low and high-cyclic loads
and post ECAE heat treatment (ECAE+HT) more effectively improves the fatigue
endurance. HA of AA6063 increased the fatigue and fretting fatigue lives of ECAE +
HT-processed samples at low cycle; however, at high cycle, HA had reverse effects,
whereby the fatigue and fretting fatigue lives of ECAE + HT-processed samples
reduced.
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In the second part of this research ECAE was utilized to produce metal tubes with
ultrafine grain (UFG) structures. To mitigate plastic instability effects such as tube
buckling and fracture during processing, hydraulic oil was used to fill the tube cavity.
Finite element analysis (FEA) was carried out to examine the feasibility of the proposed
method and deformation mechanism during ECAE. Experimental test results indicated
that the resultant 60% reduction in grain size led to significant mechanical properties
improvements including yield shear strength, ultimate shear strength, and
microhardness.
In the third phase ECAE was applied for the solid state joining of tubular AA 6061
components and SAE 1018 steel rods. The influence of using a 0.1 mm thick 60Ag-
30Cu-10Sn interlayer in addition to annealing at 220, 320, 420 and 520 °C for 60 min
was investigated as well. FEA was performed in order to evaluate the deformation
behavior of the workpieces during the ECAE joining process. The FEA outcome
showed remarkable accumulation of equivalent plastic strain with relatively low strain
inhomogeneity. Experimental results revealed that by increasing annealing temperature
and using interlayer, the joint strength was improved. According to the results, shear
strength of up to 32 MPa is feasible by having an interlayer and with subsequent
annealing at 520 °C.

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ABSTRAK
Dalam tempoh dua dekad yang lalu, tumpuan ketara telah diarahkan ke arah ubah
bentuk plastik yang teruk (SPD) sebagai kaedah langsung untuk menghasilkan logam
pukal dengan sifat-sifat mekanik yang unggul. Banyak kajian telah dijalankan untuk
membangunkan kaedah SPD untuk penghalusan bijian struktur logam dengan pelbagai
bentuk geometri dan komposisi kimia. Di antara kaedah-kaedah ini, penyemperitan
sudut saluran yang sama (ECAE) adalah teknik SPD yang paling maju disebabkan oleh
keupayaan pemprosesan komponen struktur. Sifat-sifat mekanik Pelbagai logam tulen
dan aloi telah disiasat kerja penyelidikan yang berbeza; namun ada kekurangan kajian
mengenai sifat-sifat mekanik AA 6063 diproses oleh ECAE. Lebih-lebih lagi teknik
ECAE digunakan kebanyakannya untuk penghalusan bijian komponen dengan bulat
(rod) atau segi empat tepat (rasuk) keratan rentas dan tidak ada kajian yang kukuh
kepada pembangunan teknik ini untuk memproses komponen tiub. Oleh itu, kajian
semasa memberi tumpuan kepada membangunkan ECAE untuk memproses komponen
tiub. Selain itu dalam kajian ini satu kaedah yang dibangunkan untuk keadaan pepejal
penyambungan logam yang berbeza telah dicadangkan.
Dalam fasa pertama kajian ini, sifat-sifat mekanik ECAE dirawat AA 6063 telah
disiasat. Berikutan proses ECAE, sampel juga telah tertakluk kepada rawatan haba (HT),
fosforik keras (HA), dan gabungan HT dan HA. Keletihan eksperimen dan ujian
keletihan retak, ia adalah jelas bahawa rawatan ECAE bertambah baik keletihan dan
retak kehidupan keletihan sampel pada beban rendah dan tinggi berkitar dan rawatan
haba selepas ECAE (ECAE + HT) lebih berkesan meningkatkan ketahanan lesu. HA
daripada AA6063 meningkat keletihan dan keletihan retak kehidupan sampel ECAE +
HT-diproses pada kitaran yang rendah; Walau bagaimanapun, pada kitaran yang tinggi,
HA mempunyai kesan terbalik, di mana keletihan dan retak kehidupan keletihan sampel
ECAE + HT-diproses dikurangkan.
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Dalam bahagian kedua kajian ini ECAE telah digunakan untuk menghasilkan tiub
logam dengan ultrafine bijirin (UFG) struktur. Bagi mengurangkan kesan
ketidakstabilan plastik seperti tiub lengkokan dan patah semasa pemprosesan, minyak
hidraulik telah digunakan untuk mengisi rongga tiub. Analisis unsur terhingga (FEA)
telah dijalankan untuk mengkaji kemungkinan mekanisme kaedah dan ubah bentuk
yang dicadangkan semasa ECAE. Keputusan ujian eksperimen menunjukkan bahawa
pengurangan 60% yang dihasilkan dalam saiz butiran membawa kepada peningkatan
mekanikal harta ketara termasuk kekuatan alah ricih, kekuatan ricih muktamad, dan
microhardness.
Dalam fasa ketiga ECAE dipohon keadaan pepejal penggabungan tiub AA 6061
komponen dan SAE 1018 rod keluli. Pengaruh menggunakan 0.1 mm tebal 60Ag-30Cu-
10Sn interlayer di samping penyepuhlindapan pada 220, 320, 420 dan 520 °C selama 60
minit telah disiasat juga. FEA telah dilakukan untuk menilai tingkah laku ubah bentuk
bahan kerja semasa proses menyertai ECAE. Hasil FEA menunjukkan pengumpulan
luar biasa terikan plastik bersamaan dengan ketakhomogenan tekanan rendah.
Keputusan eksperimen menunjukkan bahawa dengan meningkatkan suhu
penyepuhlindapan dan menggunakan interlayer, kekuatan bersama telah bertambah baik.
Menurut hasil, kekuatan ricih sehingga 32 MPa boleh dilaksanakan dengan mempunyai
interlayer dan dengan penyepuhlindapan berikutnya pada 520 °C.

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ACKNOWLEDGMENT

Though only my name appears on the cover of this dissertation, a great many people
have contributed to its production. I owe my gratitude to all those people who have
made this dissertation possible and because of whom my graduate experience has been
one that I will cherish forever.
I would like to thank my supervisors Professor Mohsen Abdel Naeim Hassan
Mohammad and Dr. Noor Azizi Bin Mardi for their invaluable assistance in planning
and executing this work, and for their patient advice and support through all my
research.
I wish to thank my parents, without whom I would never have been able to acquire this
degree. Their support and inspiration during my educations provided the foundation for
this work. Finally, my heartfelt thanks go to my brothers for their encouragement during
the last few years.

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TABLE OF CONTENTS

Abstract ............................................................................................................................ iii
Abstrak .............................................................................................................................. v
Acknowledgment ............................................................................................................ vii
Table of contents ............................................................................................................ viii
List of figures ................................................................................................................... xi
List of tables .................................................................................................................. xvii
List of symbols and abbreviation ................................................................................. xviii
CHAPTER 1: INTRODUCTION .................................................................................. 1
1.1. Background ........................................................................................................ 1
1.2. Problem statement .............................................................................................. 3
1.3. Objectives ........................................................................................................... 5
1.4. Scope of the thesis .............................................................................................. 6
1.5. Thesis outline ..................................................................................................... 6
CHAPTER 2: LITERATURE REVIEW ...................................................................... 8
2.1. Introduction ........................................................................................................ 8
2.2. Metals strengthening mechanisms ...................................................................... 8
2.3. Severe plastic deformation methods ................................................................. 13
2.3.1. High pressure torsion ................................................................................ 14
2.3.2. Accumulative roll bonding ........................................................................ 15
2.4. Equal channel angular extrusion ...................................................................... 16
2.4.1. Equal channel angular extrusion derivative methods and applications .... 20
2.4.2. Application of ECAE for possessing tubular components ........................ 22
2.4.3. Application of ECAE for joining dissimilar materials .............................. 24
2.5. Process parameters ........................................................................................... 26
2.5.1. Effect of die geometry ............................................................................... 26
2.5.2. Extrusion pressure ..................................................................................... 31
2.5.3. Effect of friction ........................................................................................ 32
2.5.4. Effect of pressing speed and temperature rise effect ................................ 36
2.6. Numerical simulation of ECAE process .......................................................... 39
2.7. Mechanical properties of ECAE-treated metals ............................................... 42
2.8. Research gap and aim of the present work ....................................................... 49
CHAPTER 3: RESEARCH METHODOLOGY ....................................................... 51
3.1. Introduction ..................................................................................................... 51
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3.2. Evaluation of the mechanical properties of ECAE-treated AA 6063-O .......... 52
3.2.1. Base material and Experimental details .................................................... 53
3.2.2. The ECAE processing and heat treatment ................................................ 54
3.2.3. Sample preparation for plain and fretting fatigue testing.......................... 56
3.2.4. Hard anodizing procedure ......................................................................... 57
3.2.5. Fretting fatigue test ................................................................................... 58
3.3. ECAE treatment of tubular components .......................................................... 60
3.3.1. The principle of tube-ECAE ..................................................................... 61
3.3.2. Base materials ........................................................................................... 62
3.3.3. Tube-ECAE processing and heat treatment .............................................. 63
3.4. The application of ECAE to join dissimilar metals .......................................... 65
3.4.1. The principle of ECAE joining ................................................................. 65
3.4.2. ECAE joining process and heat treatment ................................................ 66
3.4.3. Base materials ........................................................................................... 67
3.4.4. Interlayer selection and joinability ............................................................ 68
3.5. Sample preparation for mechanical and metallurgical analyses....................... 69
3.6. ECAE performance criteria .............................................................................. 72
CHAPTER 4: FINITE ELEMENT ANALYSIS ........................................................ 74
4.1. Introduction ...................................................................................................... 74
4.2. Finite element modelling of ECAE .................................................................. 75
4.3. Finite element modelling of tube-ECAE .......................................................... 77
4.4. Finite element modelling of dissimilar joining using ECAE ........................... 78
4.5. Models verification and validation ................................................................... 80
CHAPTER 5: RESULTS AND DISCUSSION ....................................................... 85
5.1. Introduction ...................................................................................................... 85
5.2. Evaluation of the mechanical properties of ECAE-treated AA 6063-O .......... 85
5.2.1. FE-simulation ............................................................................................ 85
5.2.2. Mechanical properties ............................................................................... 87
5.2.3. Fretting fatigue life .................................................................................... 91
5.3. ECAE treatment of tubular components ........................................................ 101
5.3.1. FE-simulation results .............................................................................. 101
5.3.1.1. Evolution of equivalent plastic strain .............................................. 101
5.3.1.2. Hydrostatic stress and thickness distribution analysis ..................... 103
5.3.1.3. Plastic instability .............................................................................. 107
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