Mostafa Mohamed El Sayed Abd El Aleemresearch.asu.edu.eg/bitstream/12345678/19184/1/V1242.pdf ·...

FACULTY OF ENGINEERING, CAIRO UNIVERSITY

GIZA, EGYPT

2017

EFFECT OF FRICTION STIR WELDING PARAMTERS ON THE

PEAK TEMPERATURE AND THE MECHANICAL PROPERTIES

OF AA5083-O

By

Mostafa Mohamed El_Sayed Abd El_Aleem

A Thesis Submitted to the Faculty of Engineering at Cairo University in

Partial Fulfillment of the Requirements for the Degree of

MASTER OF SCIENCE

In Mechanical Design and Production Engineering


GIZA, EGYPT

2017



OF AA5083-O

By




MASTER OF SCIENCE


Under the Supervision of

Dr. Mahmoud Mohamed Abd-Rabou

Dr. Ahmed Yehia Shash

Professor, Mechanical Design and

Production Engineering Department

Faculty of Engineering, Cairo University

Assistant Professor, Mechanical Design and

Production Engineering Department

Faculty of Engineering, Cairo University


GIZA, EGYPT

2017



OF AA5083-O

By




MASTER OF SCIENCE


Approved by the Examining Committee

ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Prof. Dr. Mahmoud Mohamed Abd-Rabou (Thesis Main Advisor)

Professor, Mechanical Design and Production Engineering Department, Faculty of

Engineering, Cairo University


Prof. Dr. Tarek Mahmoud El-Hossainy (Internal Examiner)

Professor of Mechanical Design and Production Engineering Department, Faculty of

Engineering, Cairo University


Prof. Dr. Tamer Samir Mahmoud (External Examiner)

Professor of Mechanical Design and Production Engineering Department, Faculty of

Engineering at Shoubra, Benha University

Engineer’s Name: Mostafa Mohamed El_Sayed Abd El_Aleem

Date of Birth: 6/ 11 /1987

Nationality: Egyptian

E-mail: [email protected]

Phone: 01112429062

Address: 24Suobhi Ewis st, Shoubra ElKhiema, Kalubia

Registration Date: 1/10/2012

Awarding Date: 2017

Degree: Master of Science

Department: Mechanical Design and Production Engineering

Supervisors:

Prof. Dr. Mahmoud Mohamed Abd-Rabou

Dr. Ahmed Yehia Shash

Examiners:

Prof. Dr. Mahmoud Abd-Rabou (Thesis Main Advisor)

Prof. Dr. Tarek El_Hossainy (Internal Examiner)

Prof. Dr. Tamer Samir (External Examiner)

Title of Thesis:



OF AA5083-O

Keywords:

Friction stir welding; Finite element Method; Modeling and simulation; Mechanical

properties; Tool pin profile

Summary:

This research aims to investigate the temperature distribution during FSW process of

AA5083-O numerically and experimentally. Moreover, the residual thermal stresses are

predicted by using Abaqus Finite Element Analysis program. AA5083-O plates were

friction stir welded at different conditions by variation of tool pin profile, rotational and

welding speeds. Furthermore, macrostructure, microstructure evolutions, hardness and

tensile strength examinations were performed on each friction stir welded joint.

i

Acknowledgments

Firstly, I would like to express my sincere gratitude to my advisors Prof. Dr. Mahmoud

Abd-Rabou and Dr. Ahmed Shash for the continuous support of my master study and

related research, their patience, motivation, and immense knowledge. The author is also

acknowledging Dr. Mohamed Zaki, Metallurgical and Materials Engineering

Department, Faculty of Petroleum and Mining Engineering, Suez University. The

author would like to extend his thanks to everybody in Arab Organization for

Industrialization and Arab Contractors for their support in implementing the practical

work and tests.

ii

Dedication

To my parents, my wife and my daughters

iii

Table of Contents

ACKNOWLEDGMENTS I

DEDICATION II

TABLE OF CONTENTS III

LIST OF TABLES VI

LIST OF FIGURES VII

NOMENCLATURE XI

ABSTRACT XII

CHAPTER 1 : INTRODUCTION 1

CHAPTER 2 : LITERATURE REVIEW 3

2.1 FRICTION STIR WELDING PROCESS (FSW) 3

2.1.1 OPERATION PRINCIPAL OF FSW PROCESS

3

2 .1.2 ADVANTAGES AND DISADVANTAGES OF FSW FOR ALUMINUM

JOINING

4

2.1.3 FSW APPLICATIONS 5

2.1.4 FRICTION STIR WELDING PROCESS PARAMETERS 6

2.1.5 MICROSTRUCTURE OF FRICTION STIR WELDED ALUMINUM JOINTS 10

2.1.6 MECHANICAL PROPERTIES OF FRICTION STIR WELDED ALUMINUM

JOINTS

14

2.1.7 HEAT GENERATION DURING FRICTION STIR WELDING PROCESS 22

iv

2.1.8 FINITE ELEMENT MODELING OF FRICTION STIR WELDING 23

2.2 SUMMARY

26

CHAPTER: 3 FINITE ELEMENT MODELING AND EXPERIMENTAL

INVESTIGATION

27

3.1 SCOPE OF RESEARCH 27

3.2 FINITE ELEMENT MODELING

29

3.2.1 IDEALIZATION

29

3.3 EXPERIMENTAL INVESTIGATION

35

3.3.1 TOOL DESIGN

35

3.3.2 WORK PIECE DESIGN 36

3.3.3 MACHINE SET UP AND OPERATION CONDITIONS 37

3.4 TESTING

39

3.4.1 MATERIAL CHARACTERIZATION

39

3.4.2 MECHANICAL PROPERTIES 39

CHAPTER 4: RESULTS AND DISCUSSION 42

4.1 FINITE ELEMENT MODELING 42

4.1.1 TEMPERATURE DISTRIBUTION SIMULATED FROM THE HEAT

TRANSFER MODEL

42

4.1.2 RESIDUAL THERMAL STRESSES OBTAINED FROM THE THERMO-

MECHANICAL MODEL

46

4.2 EXPERIMENTAL INVESTIGATION 52

v

4.2.1 EFFECT OF FRICTION STIR WELDING PARAMETERS ON THE PEAK

TEMPERATURE DURING THE WELDING PROCESS

52

4.2.2 COMPARISON BETWEEN THE SIMULATED AND THE MEASURED

TEMPERATURES

52

4.2.3 SURFACE MORPHOLOGY

55

4.2.4 MACROSTRUCTURE OF FRICTION STIR WELDED JOINTS AT DIFFERENT

OPERATION CONDITIONS

56

4.2.5 EFFECT OF FSW PARAMTERES ON THE MICROSTRUCTURE

EVOLUTIONS OF THE WELDED JOINTS

57

4.2.6 EFFECT OF FSW PARAMETERS ON THE MICROHARDNESS OF THE

WELDED JOINTS

70

4.2.7 EFFECT OF FSW PARAMETERS ON THE TENSILE STRENGTH VALUES

OF THE WELDED JOINTS

75

CONCLUSIONS

79

FUTURE WORK 80

REFERENCES 81

vi

List of Tables

Table 2.1 The effect of FSW parameters 6

Table 2.2 The relationship between the different contact conditions 23

Table 3.1 Temperature dependent thermal properties of AA5083 30

Table 3.2 Temperature dependent mechanical properties of AA5083 31

Table 3.3 The chemical composition of K720 36

Table 3.4 The chemical composition of AA5083-O 37

Table 3.5 The mechanical properties of AA5083-O 37

Table 3.6 FSW operation conditions 38

Table 4.1 The peak temperature variation due to variation of FSW parameters 55

Table 4.2 Average hardness values in the welding zone at various FSW conditions 75

Table 4.3 Tensile strength values at various FSW conditions 77

vii

List of Figures

Figure 2.1 FSW process set up 3

Figure 2.2 Schematic illustration of stages of FSW process 4

Figure 2.3 Schematic drawing of FSW tool 7

Figure 2.4 The commonly used tool pin profiles in FSW 7

Figure 2.5 The Whorl™ type probes 7

Figure 2.6 The Flared-Triflute™ type probes 8

Figure 2.7 Schematic drawing of tool tilting 9

Figure 2.8 The acting forces on the FSW tool 10

Figure 2.9 Schematic cross section showing zones of Al friction stir welded

joint

10

Figure2.10 Typical macrograph showing microstructure zones of AA2024 10

Figure2.11 Optical microstructures (SEM images) of FSW joint of 6013 T6 11

Figure 2.12 Optical microstructures of SZ at different rpms 12

Figure 2.13 Relationship between rotational speed and grain size of SZ of 2024-

T3

13

Figure 2.14 The effect of welding parameters on microstructures of DXZ of

AA2060 FSWed

13

Figure 2.15 Effect of welding and rotational speeds on the grain sizes in DXZ of

AA2060 FSWed

14

Figure 2.16 Hardness traces of AA5083-O and AA5083-H321 FSWed 15

Figure 2.17 Microhardness profiles and fracture locations of AA6061-T6 FSWed

at different welding conditions

16

Figure 2.18 Vickers Hardness profiles of FSWed joint cross section of AA5083

H-111

17

Figure 2.19 The effect of rotational speed on tensile properties of AA2024-T3

FSWed

18

Figure 2.20 Tensile strength variation of AA 5083-H111FSWed 19

Figure 2.21 The effect of rotational speed and tool pin profile on UTS of

AA5083-H111 FSWed

19

viii

Figure 2.22 Effect of welding speed on tensile properties of AA6061-T651

FSWed at 1600 rpm

20

Figure 2.23 Effect of rotational speed on tensile properties of AA6061-T651

FSWed at 0.2 mpm

20

Figure 2.24 Longitudinal residual stresses produced due to FSW of AA2024-

T351

21

Figure 2.25 Simulation of peak temperatures of AA6061-T6 at different

rotational and welding speeds

24

Figure 2.26 Numerical and experimental longitudinal residual stresses in cross

section of AA7075-T6 FSWed

25

Figure 2.27 The measured transverse residual stresses along and parallel to the

welding line of AA7075-T6 FSWed

25

Figure 3.1 Block diagram of the research plan 28

Figure 3.2 Block diagram of the finite element modeling 29

Figure 3.3 Part geometry 30

Figure 3.4 Boundary conditions subjected to the model 34

Figure 3.5 Thermal load subjected to the part 34

Figure 3.6 Part meshing 35

Figure 3.7 Schematic drawing of FSW tools 36

Figure 3.8 Machine set up 37

Figure 3.9 Schematic drawing of FSW process 38

Figure 3.10 Fluke IR thermal image camera 38

Figure 3.11 The measured temperature by using IR camera 38

Figure 3.12 OLYMPUS optical microscope 39

Figure 3.13 ZWICK/ROELL hardness testing machine 40

Figure 3.14 Schematic drawing of tension test sample cutting position 41

Figure 3.15 Schematic drawing of tension test specimen 41

Figure 3.16 Tension testing machine 41

Figure 4.1 Simulated temperature contour at different rotational speed values 42

Figure 4.2 Simulated temperature distribution plot perpendicular to the welding

line at different rotational speed values

43

Figure 4.3 Simulated temperature distribution plot along the welding line at

different rotational speed values

44

ix

Figure 4.4 Simulated temperature distribution plot along the model thickness at

different rotational speed values

45

Figure 4.5 Temperature history after 30 min. cooling for both rotational speeds 47

Figure 4.6 The longitudinal residual stresses contour at different rotational

speeds

48

Figure 4.7 The transverse residual stresses contour at different rotational speeds 48

Figure 4.8 The longitudinal residual stress plot at several paths perpendicular to

the welding line

49

Figure 4.9 The transverse residual stress plot at several paths along and parallel

to the welding line

50

Figure 4.10 The measured longitudinal residual stress obtained by Peel et al. 51

Figure 4.11 The measured transverse residual stresses along and parallel to the

welding line obtained by Buffa et al.

51

Figure 4.12 Variation of peak temperature due to variation of FSW parameters 53

Figure 4.13 Comparison between measured and simulated temperature

distributions at different rotational speed values

54

Figure 4.14 Surface morphologies of the welded joints by threaded tool pin

profile at different rotational and welding speeds

55

Figure 4.15 Surface morphologies of the welded joints by tapered tool pin profile

at different rotational and welding speeds

56

Figure 4.16 Macrostructure of the traverse cross section of the welded joints by

threaded pin at different rotational and welding speed values

57

Figure 4.17 Macrostructure of the traverse cross section of the welded joints by

tapered pin at different rotational and welding speed values

57

Figure 4.18 Microstructure of the welded joint by threaded pin at 400 rpm&50

mm/min

58


mm/min

59


mm/min

60


mm/min

61

x


mm/min

62


mm/min

63

Figure 4.24 Microstructure of the welded joint by tapered pin at 400 rpm & 50

mm/min

64

Figure 4.25 Microstructure of the welded joint by tapered pin at 400 rpm &100

mm/min

65

Figure 4.26 Microstructure of the welded joint by tapered pin at 400 rpm&160

mm/min

66


mm/min

67


mm/min

68


mm/min

69

Figure 4.30 Microhardness profile of the joints by the threaded pin profile at 400

rpm and different welding speeds

71

Figure 4.31 Microhardness profile of the joints by the threaded pin profile at 630


72

Figure 4.32 Microhardness profile of the joints by the tapered pin profile at 400


73

Figure 4.33 Microhardness profile of the joints by the tapered pin profile at 630

rpm and different welding speed

74

Figure 4.34 Effect of FSW parameters on the tensile strength values of the

welded joints

76

Figure 4.35 Fracture positions of the welded joints by threaded tool pin profile 77

Figure 4.36 Fracture positions of the welded joints by tapered tool pin profile 78

xi

Nomenclature

The contact shear stress

The friction coefficient

The contact pressure

The frictional heat generation

The slip rate

The contact state variable

The velocity of the tool

The velocity of the work piece

The rate of heat generation due to plastic energy dissipation

The factor of conversion of mechanical to thermal energy

The plastic strain rate

ρ The density

cp The specific heat

k The thermal conductivity

T The temperature

t The time

Q The heat flux

q The heat input

The angular velocity

n The rotational speed

F The axial force

R The shoulder radius

r The pin radius

ij The total strain

ijM

The strain contributed by the mechanical forces

ijT The stain from thermal loads

ijE The elastic strain

ij The Kronecker delta function

E The Young‟s modulus,

ν The Poisson‟s ratio,

α: The thermal expansion coefficient

The temperature difference of two different material points

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