v
LIST OF FIGURES
2.1
Steps of ductile material failure, extensive plastic deformation takes place before fracture
20
2.2 Fractograph of Ductile Material
21
2.3
Fractograph of Brittle Material 21
2.4 Fracture Of an Aluminum Crank brittle
21
2.5 Ductile Failure Of A Specimen Strained
22
2.6
Applying A Force to Enable a Crack propagate 23
2.7 Specimen for Fracture Toughness Test
24
2.8 Reaction and Fracture Direction during Fracture Toughness Test
24
2.9
Reaction between water, rust, and oxygen create pitting corrosion 25
2.10 Corrosion rate influence the aggressive environment and temperature
27
3.1 Flow Chart of Research Design
31
3.2
Dimension of Specimen for heat treatment and corrosion process. 33
3.3 Flow Chart Process for Heat Treatment
34
3.4 Immersion Sample in Chemical Solution
37
3.5
Surface of Sample after Corrosion Process. 38
3.6 Sample for Fracture Toughness Test
39
3.7 Dimension of Specimen for Toughness Test
40
3.8
Principal Types of Load Displacement for Toughness Test 41
3.9 Direction of Specimen During Testing
42
3.10 Universal Testing Machine UTM 42
vi
LIST OF FIGURES
3.11 Direction of Gage During The Measurement 43
3.12 Vickers Hardness Testing Machine for Measuring Hardness 44
3.13 Optical Microscope
45
4.1 Graph Of Fracture Toughness of AA7075
49
4.2 Comparison Graph of Hardness Value between Samples in Different
Temperature of Heat Treatment 51
4.3 Comparison Graph of Hardness Value of Across Material between
Samples in Different Temperature of Heat Treatment 52
4.4
Comparison Graph of Hardness Value of Surface Material between Samples in Different Temperature of Heat Treatment
53
4.5 Microstructure of A1 Sample, As a Received Material of AA7075
55
4.6
Microstructure of A3 Sample, As a T6 Sample of AA7075 56
4.7
Microstructure of A5 Sample, As a RRA Sample of AA7075 57
vii
LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED NOMENCLATURE
UTeM -
University Technical Malaysia Malacca AA7075
- Aluminum Alloy 7075
RRA -
Retrogression and Re-Aging Treatments SCC
- Stress- Corrosion Cracking
Al -
Aluminum Zn
- Zinc
Mg -
Magnesium Cu
- Copper
FCC -
Face Centered Cubic SSSS
- Supersaturated Solid Solution
GP -
Guinier-Preston CT
- Compact Test
SENB -
Single Edge Notch Bend Cl
- Chloride
SEM -
Scanning Electron Microscope UTM
- Universal Tester Machine
ASTM -
American Society for Testing and Materials LEFM
- Linear-Elastic Fracture Mechanics
EPFM -
Elastic-Plastic Fracture Mechanics K
Ic
- Toughness
K -
Stress Intensity MPa
- Mega Pascal
m -
meter nm
- nanometer
ºC -
degree Celsius
viii
LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED NOMENCLATURE
EXCO -
exfoliation corrosion NaCl
- sodium chloride
KNO3 -
potassium nitrate HNO3
- nitric acid
ix
TABLE OF CONTENTS
Abstract i
Acknowledgement ii
List of Tables iii
List of Figures iv
List Of Abbreviations, Symbols, Specialized Nomenclature vi
Table Of Contents vii
CHAPTER 1 : INTRODUCTION
1.1 Introduction 1
1.2 Problem Statement 2
1.3 Objectives 3
1.4 Scope 3
CHAPTER 2 : LITERATURE REVIEW
2.1 Introduction of Aluminum 4
2.1.1 Aluminum Alloys 5
2.1.2 Aluminum Alloys 7075 7
2.2 Heat Treatment 10
2.2.1 Temper Designation System 11
2.2.2 System For Heat Treatable Aluminum Alloys 12
2.2.2.1 Solution Heat Treatment 13
2.2.2.2 Quenching 14
2.2.2.3 Age Hardening 15
2.2.2.4 Retrogression and re-ageing RRA
17
x
2.3 Fracture Mechanics
18 2.3.1 Linear-elastic fracture mechanics LEFM
19 2.3.2 Fractography
20 2.3.2.1 Fracture Toughness
22 2.4 Corrosion
25 2.4.1 Corrosion in Aluminum Alloy 7075
26 2.4.2 Stress Corrosion Cracking of Aluminum Alloys
28
CHAPTER 3 :
METHODOLOGY 3.1 Introduction
30 3.2 Research Design
31 3.3 Material Selection
32 3.4 Sample preparation
33 3.5 Heat Treatment
34 3.5.1 T6 temper
35 3.5.2 RRA Treatment
35 3.5.3 List of Specimen
36 3.6 Corrosion
37 3.7 Notch Preparation
39 3.8 Testing And Analysis
40 3.8.1 Fracture toughness
40 3.8.2 Hardness
44 3.8.3 Microscope Observation
45 3.8.3.1 Optical Microscope
45
xi
CHAPTER 4 : RESULT AND DISCUSSION 4.1
Fracture toughness properties of heat treated AA7075 46
4.1.1 Tensile Strength properties of AA7075
47 4.1.2
Fracture toughness data 48
4.2 Hardness properties of AA 7075
50 4.2.1
Hardness properties of heat treated and corroded AA 7075 51
4.3 Microstructure of Aluminum Alloy 7075
54 4.3.1
Microstructure of heat treated Aluminum Alloy 7075 55
CHAPTER 5 : CONCLUSION AND RECOMMENDATIONS 5.1 Conclusions:
58 5.2 Recommendations
61
REFERENCES 63
APPENDICES A: Gantt Chart
69 B: Drawing of fracture toughness sample
72
1
CHAPTER 1
INTRODUCTION
In this chapter, it will present briefly about heat treated Aluminum Alloy 7075, and problem that influence on AA7075 in aircraft application. We also briefly explain about
the objectives and scope of this research.
1.1 Introduction
