influence of steel composition on the mechanical...
TRANSCRIPT
INFLUENCE OF STEEL COMPOSITION ON THE MECHANICAL
PROPERTIES AND Zn-Mg-Al COATING LAYER ON THE CORROSION
RESISTANCE OF STEEL WIRE ROPES FOR OFFSHORE APPLICATIONS
MYUNG HYUN CHO
A thesis submitted in fulfilment of the
requirements for the award of the degree of
Doctor of Philosophy (Mechanical Engineering)
Faculty of Mechanical Engineering
Universiti Teknologi Malaysia
JUNE 2016
v
DDDDedicateedicateedicateedicatedddd to
My chairman, My family, My Supervisor
&
Kiswire Top Management
vi
ACKNOWLEDGEMENT
How fast time flies! Five years have been almost passed. I am coming to the
end of a road. I felt that I am not alone on this road, many people have been together
with me along this journey and I acknowledge their help.
I would like to express my deepest sense of obligation and gratitude to my
chairman, Mr. Hong Young Chul for giving me the opportunity to do this study and
all the moral support and expenses.
I would like to express my sincere appreciation to my thesis supervisor, Prof.
Dr. Esah bt Hamzah for her continous support, valuable advice and motivation
throughout the completion of this work . My gratitude also extended to my former
supervisor, Prof. Dr. Ali Ourdjini, OTTAWA University, Canada, for his
supporting , guidance and assitance in the Mg alloy zinc coating experiment aspects
of my research.
I extend my heartfelt thanks to CEO, Charles Lee, Scott Hong and Korean
staffs of KISWIRE SEA HQ for their constant encouragement, they have been my
finest balm during this journey.
My sincere appreciation also extends to my R&D Researchers, Mr. Faiq and
others who have provided assistance at various testings. I shall never forget the
endless encouragement and assistance they had provided.
Finally, I am very grateful to my wife and sons for their endless affection,
patience, interest and constant encouragement. There are still many people that I am
very grateful for their help and support thoughout this journey which I do not specify
here.
vi
ABSTRACT
Steel rope is generally used for mooring application. Recently, higher
strength and corrosion resistance are required to avoid the weight penalty with
increase of the sea-water depth in offshore oil production. This can be achieved by
increasing the carbon content and adding alloy elements in zinc coating. Three
objectives of the research were conducted as follows; to investigate the effect of
composition on strength and corrosion resistance of galvanized wire, to investigate
the degradation mechanism of high tensile strength (2,150 ~2,250MPa) galvanized
steel rope in sea-water and to develop a Zn-Al-Mg ternary alloy coating to enhance
the corrosion resistance of steel ropes. Microstructural characterisation on coated
steel wires was carried out using optical microscope, field emission scanning
electron microscope (FESEM) equipped with energy dispersive spectrometer (EDS)
and X-ray diffractometer (XRD). Both Tafel polarization and salt spray tests were
conducted to investigate the corrosion resistance of Zn-Mg-Al alloy coatings.
Torsion, fatigue and tensile tests were conducted. The best fatigue property was
obtained at 2,167MPa tensile strength. Tensile strength above 2,167MPa, fatigue and
torsion properties were reduced and the susceptibility to surface defect also was
increased during fatigue testing, by which cracks can be easily created and grown at
different planes at the same time. It is the main cause of fatigue degradation.
Degradation of mooring rope is caused by combination of fretting and corrosion
which normally occurs in wire rope assembly type known as Independent Wire Rope
Core (IWRC). Excellent corrosion resistance over 3,000 hours based on salt spray
test was obtained by addition of magnesium and aluminium elements in the range of
1.0~3.0wt% but no improvement for over 3wt% Mg, which might be attributed to
coarsening of the phase grains. The multi-layer coatings in which each layer consists
of several different alloy phases has an advantage because each phase has a unique
function and they exert their synergic functions in corrosion environment. As a
conclusion, applying Zn-Mg-Al coating to mooring rope improves life span of rope
due to reduced crack in the coating and excellent corrosion resistance.
vi
ABSTRAK
Tali keluli secara umumnya digunakan untuk aplikasi menambat. Mutakhir
ini, kekuatan yang tinggi dan rintangan terhadap kakisan adalah diperlukan untuk
mengelakkan penalti berat terhadap pertambahan kedalaman air laut pada
penghasilan minyak di luar pesisir pantai. Ini dapat dicapai dengan meningkatkan
kandungan karbon dan menambah unsur aloi dalam salutan zink. Tiga objektif kajian
yang telah dilaksanakan adalah seperti berikut; mengkaji kesan komposisi terhadap
kekuatan dan rintangan kakisan dawai tergalvani, mengkaji mekanisma degradasi
kekuatan tegangan tinggi (2,150 ~ 2,250 MPa) tali keluli tergalvani di dalam air laut
dan menghasilkan salutan aloi pertigaan Zn-Al-Mg untuk meningkatkan rintangan
kakisan terhadap tali keluli. Pencirian mikrostruktur pada dawai keluli tersalut telah
dilaksanakan dengan mengunakan mikroskop optik, mikroskop medan pancaran
elektron imbasan (FESEM) yang dilengkapi dengan spektrometer serakan tenaga
(EDS) serta pembelau sinar-X (XRD). Kedua-dua polarisasi Tafel dan ujian
semburan air garam telah dijalankan untuk mengkaji sifat rintangan kakisan salutan
aloi Zn-Mg-Al. Ujian kilasan dan tegangan telah dijalankan. Sifat kelesuan yang
paling tinggi dicatat pada 2,167 MPa. Kekuatan tegangan melebihi 2,167 MPa, sifat
kilasan dan lesu berkurang dan kerentanan terhadap kecacatan permukaan meningkat
apabila ujian kelesuan, di mana retak mudah terbentuk dan pada masa yang sama
merebak pada satah yang berbeza. Ini adalah faktor utama degradasi kelesuan.
Degradasi tali penambat adalah disebabkan kombinasi diantara perlagaan antara
dawai dan kakisan yang lazim berlaku pada jenis perhimpunan tali dawai dikenali
sebagai Independent Wire Rope Core (IWRC). Rintangan kakisan yang terbaik dapat
diperolehi pada jangka masa melebihi 3,000 jam berdasarkan kepada ujian semburan
garam dengan penambahan unsur magnesium dan aluminium dalam lingkungan
1.0~3.0% berat namun tiada penambahbaikan selepas melebihi 3% berat Mg,
mungkin disebabkan oleh pembesaran fasa bijian. Salutan pelbagai-lapisan yang
mana setiap lapisan mengandungi beberapa fasa aloi berbeza mempunyai kelebihan
kerana setiap fasa memiliki fungsi unik dan memberi fungsi sinergi di dalam
persekitaran kakisan. Kesimpulannya, mengaplikasikan salutan Zn-Mg-Al kepada
tali penambat dapat menambah baik jangka hayat tali disebabkan salutan mempunyai
keretakan yang lebih rendah dan rintangan kakisan yang lebih tinggi.
vii
TABLE OF CONTENTS
CHAPTER TITLE PAGE
TITLE i
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xii
LIST OF FIGURES xiii
LIST OF ABBREVATIONS xxiii
1 INTRODUCTION 1
1.1 Background of the Research 1
1.2 Problem Statement 3
1.3 Objectives of the Research 4
1.4 Scope of Work 5
viii
2 LITERATURE REVIEW 6
2.1 Introduction 6
2.1.1 Steel Rope Manufacturing 6
2.1.2 Mooring System 8
2.2 Strengthening of Steel Wires 9
2.2.1 Influence of Alloying Elements on
Strengthening of High Carbon Steel
10
2.2.2 Influence of Microstructure on Strengthening
of High Carbon Steel
13
2.3 Fatigue Characteristic Behavior of Hyper-eutectic
Pearlitic Drawn Wires
14
2.3.1 Parameters Influencing Fatigue Property of
Drawn Wire
15
2.4 Mooring Steel Wire Rope Degradation Factors 22
2.4.1 Wire Rope Endurance in Sea Water 24
2.4.2 Parameters Influencing Fretting Wear 28
2.5 Improvement of Corrosion Resistance by Magnesium
Alloy Zinc Coating
30
2.5.1 Technology Trend 30
2.5.2 Morphology and Corrosion Behavior of Zn-
Mg-Al Coating According to Its Chemical
Composition
32
2.5.3 Effect of the Alloying Elements 40
2.6 Summary 41
3 METHODOLOGY 43
3.1 Introduction 43
3.2 The Effect of Chemical Composition on Strength and
Corrosion Resistance of Galvanized High Strength
Steel
47
3.2.1 Materials and Samples for Investigating The 48
ix
Effect of Chemical Composition on
Delamination and Zn-Fe Alloy Formation of
Galvanized Wire
3.2.2 Materials and Sample Preparation for
Investigating The Effect of Tensile Strengthon
Fatigue Life of Strand After Stranding Process
49
3.2.3 Materials and Samples for Investigating The
Effect of Zn-Fe Alloy layer on Corrosion
52
3.3 Degradation of Rope in Sea Water 53
3.4 Investigation on The Corrosion Resistance of Steel
Wire in Sea Water by Adding Alloying Elements
into Molten Zinc Bath
56
3.4.1 Materials and Samples Preparation 56
3.4.2 Melting Pot Temperature Control 58
3.5 Characterization Techniques 59
3.5.1 Microstructure and EDX Chemical Analysis 59
3.5.2 Inductively Coupled Plasma Mass
Spectrometry (ICP-MS) and Inductively
Coupled Plasma Emission Spectrometry
(ICP-OES) Chemical Analysis
61
3.5.3 Determination of Mechanical Properties 62
3.5.3.1 Torsion and Tensile Test 62
3.5.3.2 Fatigue Test 64
3.5.4 Corrosion Test 66
3.5.4.1 Corrosion of Rope in Sea-Water 66
3.5.4.2 Salt Spray Corrosion Test 69
3.5.4.3 Electrochemical Test
(Polarization/Tafel Curve)
71
4 RESULTS AND DISCUSSION 74
4.1 Introduction 74
4.2 The Effect of Chemical Composition of Steel on 75
x
Strength and Corrosion Resistance of Galvanized
Steel
4.2.1 The Effect of Chemical Composition on
Delamination and Zn-Fe Alloy Formation of
Galvanized Steel Wire
75
4.2.2 The Effect of Tensile Strength on the fatigue
Life of Strand After Stranding Process
85
4.2.2.1 Fatigue Effect 85
4.2.2.2 Fracture Morphology Behaviour 88
4.2.3 The Effect of Zn-Fe Alloy Layer Thickness on
The Corrosion Resistance of Galvanized Wire
104
4.3.4 Summary 113
4.3 Degradation of Steel Rope in Seawater 115
4.3.1 Appearance of Steel Rope Used for 3.5 Years
in Deep Sea Mooring Applications
115
4.3.2 Corrosion Rate of Wires According to Wire
Position
119
4.3.3 Corrosion Morphology of Wires as Function
of the Wire Position
121
4.3.4 Summary 136
4.4 Effect of Alloy Coating Composition on the
Corrosion Resistance of Zn-Mg-Al Coatings
138
4.4.1 Morphology Behavior of Alloy Coating
According to Their Chemical Compositions
139
4.4.1.1 Zn – 0.5wt % Mg – 0.5wt% Al Alloy
Coating
139
4.4.1.2 Zn – 1.0wt % Mg – 1.0wt% Al Alloy
Coating
146
4.4.1.3 Zn – 2.0wt % Mg – 2.0wt% Al Alloy
Coating
150
4.4.1.4 Zn – 3.0wt % Mg – 2.0wt% Al Alloy
Coating
155
4.4.1.5 Z Zn – 3.0wt % Mg – 6.0wt% Al Alloy 160
xi
Coating
4.4.1.6 Zn – 5.0wt % Mg – 5.0wt% Al Alloy
Coating
166
4.4.1.7 Morphology of Alloy Melting Pot
Ingot
170
4.4.1.8 Summary of Morphology of Alloy
Coatings
175
4.4.2 Corrosion Behaviour of Alloy Coating
According to Their Coating Chemical
Composition
176
4.4.2.1 Corrosion Test (Polarization/Tafel) and
Salt Spray Test
176
4.4.2.2 Morphology of the Corrosion Product 177
4.4.2.3 Morphology of Coated Steel Cross
Sections after Salt Spray Test
184
4.4.2.4 Morphology of Coating of steel wire
drawn after coating
192
4.4.3 Summary 194
5 CONCLUSION 197
5.1 Conclusion 197
5.2 Recommendation for the Future Work 199
REFERENCES 200
xii
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Properties of inter-metallic alloy phases in hot-dip
galvanizing
18
2.2 The rate of Zinc dissolution in tropical seas, in most of
South East Asian countries
23
2.3 Suggestions provided by API and DNV for service life in
years, based on various rope constructions
23
2.4 Fretting-corrosion wear volume measurements for
galvanized and bright wires in air sea water
29
2.5 Fretting corrosion wear volume measurement for bright
wires in air and sea water, with applied potential
29
2.6 Electro polarization test results of coatings having different
alloy contents. Testing condition: 3.5% NaCl solution of pH
7.5, Icorr and Ecorr values by Tafel plot and the corrosion rate
(mpy)
39
3.1 Chemical compositions of steels used to investigate the
effect of steel composition on mechanical properties of
galvanized drawn wires
49
3.2 Materials and loading conditions for fatigue test of strands
according to tensile strength grades
50
3.3 Materials with different Zn-Fe alloy thickness 52
3.4 Tensile strength and diameter of the wires inside rope 55
3.5 Composition of Zn-Mg-Al alloy coating samples 57
4.1 Work hardening and lamellar spacing versus chemical
composition of steels
78
xiii
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 Schematic showing how ropes are constructed: (a)
Sheathed spiral strand and (b) 6 strand rope
7
2.2 Illustration of a turret anchored Floating Production,
Storage and Offloading (FPSO). Courtesy of APL/Axis
9
2.3 Effect of Si content on tensile strength of lead patented
wires and Stelmor-cooled wire rods
11
2.4 Torsion fracture types and their evaluation grades 16
2.5 Delamination of torsion testing 16
2.6 Alloy phases of hot-dip galvanizing coating 18
2.7 A schematic drawing of Fe-Zn alloy phase formation in
pure molten Zn bath
19
2.8 Effect of immersion time on Iron loss as a function of
percentage Si content
21
2.9 The rates of relative dissolution of galvanized coating from
steel wire continuously wetted with water, normalized to 1
at 5° C
22
2.10 Histogram showing the amount of remaining zinc coating
in the individual wires of a 70 mm diameter six strand rope
(6x37+IWRC) after 12 years of marine exposure in the
splash zone (unloaded)
25
2.11 Histogram showing the amount of remaining zinc coating
on the 19 individual wires of a 89 mm diameter six strand
rope (6x49+IWRC) after 10 years of marine exposure as a
catenary (loaded)
26
xiv
2.12 Summary of single wire tensile fatigue tests from AERE
study
27
2.13 Cross sectional SEM and EDX images of coating layer in
Zn-Al-Mg alloy coating (11wt%Al,3wt%Mg,0.2wt%Si ): a)
SEM image, b) Al, c) Mg, d) Zn
33
2.14 Scanning electron microscope images of Zn-5wt%Al-
0.5wt%Mg -0.08wt%Si coating and EDX analysis
34
2.15 SEM cross-sectional micrographs of Zn-2wt%Al-2wt%Mg
coated steel sheet produced by hot-dipping
35
2.16 Surface morphology of coating and EDX analysis (wt. %):
(a) Zn-2.5 Mg, (b) Zn-0.5Mg, (c) Zn-0.5Mg-0.25Al
37
2.17 SEM microstructures and EDX analyses for three coating
samples produced by dipping for 10 seconds in molten bath
at 420 °C
38
2.18 SEM microstructures of ZnAlMgSi coating after 28 days of
exposure to humid air
40
3.1 Flow chart of research methodology : (a) Phase 1, (b) Phase
2, (c) Phase 3
46
3.2 (a) Drawing machine. (b) Stranding machine – Tubular-
Type
51
3.3 Cross-sectional view of the rope 54
3.4 Whole process of first and second hot-dip galvanizing 57
3.5 Melting furnace 58
3.6 Torsion test: (a) setup specimen in torsion tester, (b)
delamination measuring device
63
3.7 Set up strand specimen in Instron tension-tension fatigue
testing machine
65
3.8 Socketing of sample for tension-tension fatigue testing 65
3.9 Appearance of rope after being used for 3.5 years for the
mooring application
68
3.10 Wires after rope was dismantled 68
3.11 Salt spray testing; (a) salt spray test machine, (b) specimen
position in the chamber
70
xv
3.12 Specimen for electrochemical polarization test and
impedance spectra test: (a) schematic drawing (b) actual
specimen
72
3.13 The complete electrochemical corrosion test: (a) three
electrode electrochemical test cell (b) complete set-up
72
3.14 Typical polarization/Tafel curve 73
4.1 True stress-true strain plot showing work hardening rates for
steels with different carbon content
77
4.2 FESEM microstructures of (a) 97B DLP (0.043 µm) and (b)
98B LP (0.061 µm) with different lamellar spacing
77
4.3 Torsion values versus strain for four steels: 87B DLP
13mm, 92BLP 12mm, 97B DLP 11.5mm, 98B LP 12mm
79
4.4 Delamination of drawn wire 4.30mm for 97B DLP 11.5mm:
(a) whole fracture appearance, (b) cross-section surface of
fracture, (c) enlargement of (b)
80
4.5 Torque as a function of elapsed time 81
4.6 Micro-crack formations due to gamma layer of cold drawn
wire in 92B LP steel, (a) micro-crack in the surface of steel,
(b) enlargement of (a)
82
4.7 Crack propagation morphology of delamination during
drawing of 98B-0.60% Si: (a) whole appearance of torsion
fracture, (b) opposite part of (a), (c) enlargement of (b)
indicated by arrow
83
4.8 Alloy layer thickness as function of Si% in: (a) 97B-0.2% Si
and (c) 92B-1.3% Si, (b) EDX line scan analysis of (a), (d)
EDX line scan analysis of (c)
84
4.9 Tension-tension fatigue and torsion value according to
tensile strength
86
4.10 The effect of surface defect on tension-tension fatigue
according to tensile strength
87
4.11 Fractography of failed inner wire during tension-tension
fatigue testing of strand with 2,108 MPa (Longer fatigue:
558,432 cycles): (a) whole fracture surface, (b) whole
89
xvi
fracture surface at different angle, (c) enlargement of area,
B of (a), and (d) enlargement of area, A of (a)
4.12 Fracture surfaces of failed outer wire during tension-tension
fatigue testing of strand with 2,108 MPa (Longer fatigue:
558,432 cycles) : (a) fracture mode, (b) fracture mode of
matching part of broken wire, (c) enlargement of fatigue
fracture propagation in zone, A of (a), and (d) enlargement
of fatigue fracture propagation in zone, B of (a)
91
4.13 Fractography of outer wire fractured during tension-tension
fatigue testing of strand with 2,108MPa (Longer fatigue:
446,760 cycles) : (a) Whole fracture surface, (b) micro
crack on the longitudinal surface of the crack initiation site,
(c) enlargement of the fatigue fracture propagation in the
fracture initial part (e), (d) enlargement of surface crack (e),
and (e) fracture initial part in the micro-crack area
93
4.14 Fracture surfaces of inner wire fractured during tension-
tension fatigue testing of strand with 2,167 MPa (Longer
fatigue: 599,144 cycles): (a) whole fracture surface, (b)
enlargement of window area in a, and (c) enlargement of
window area in b
95
4.15 Fracture surfaces of outer wire fractured during T-T fatigue
testing of strand with 2,167 MPa (Longer fatigue: 599,144
cycles): (a) whole fracture surface, (b) whole fracture
surface of other part, (c) enlargement of red window area in
A, and (d) enlargement of yellow window area in B
96
4.16 Fracture of outer wire fractured during T-T fatigue testing
of strand with 2,167 MPa (shorter fatigue: 164,540 cycles):
(a) shear fracture of the broken wire, (b) enlargement of (a),
(c) shear fracture of another broken wire, and (d)
enlargement of the red circle of (c)
97
4.17 Fracture surfaces of outer wire fractured during T-T fatigue
testing of strand sample I with 2,236 MPa (shorter fatigue:
221,043 cycles): (a) enlargement of zone, A of (b), (b)
99
xvii
whole fracture surface, (c) enlargement of zone, B of (b),
(d) whole fracture surface in another direction, (e)
enlargement of circle of (f), and (f) enlargement of circle of
(d)
4.18 Fracture surfaces of outer wire fractured during T-T fatigue
testing of strand with 2,236 MPa: shorter fatigue: 221,043
cycles: (a) fatigue crack - enlargement of zone, A of (b), (b)
whole fracture surface, (c) surface crack - enlargement of
zone, B of (b), (d) propagation of crack from Zn alloy to
steel matrix - enlargement of yellow circle of (d), (e)whole
fracture surface in another direction, and (f) fatigue crack -
enlargement of red circle of (f)
101
4.19 Fracture morphology behaviors of outer wires according to
tensile strength during T-T fatigue testing of strand: (a)
2,108 MPa, (b) 2,167 MPa, (c) 2,236 MPa: multi-place
fatigue cracks, and (d) 2,236 MPa: different level cracks
103
4.20 Salt spray hours vs. alloy layer thickness ratio (%) 105
4.21 Cross-section of the Zn coating of the sample without
cracks after 310 hours exposure to the salt spray test
106
4.22 Behavior of corrosion progress of a sample with a crack
within the coating layer after 310 hours exposure to the salt
spray test
106
4.23 Crack propagation behavior of Zn coating from galvanized
rod to drawing: (a) galvanized rod 11.5mm, (b) enlargement
of alloy layer of (a), (c) 5.14mm drawn wire (Reduction:
80%), (d) 4.71m drawn wire (Reduction: 83%), and (e)
4.31mm drawn wire (Reduction: 86%)
108
4.24 Corrosion behavior versus crack size of Zn coating after 310
hours salt spray test for samples: K, L, M, N, O, and P
110
4.25 Effect of heat treatment on corrosion behavior versus crack
size of Zn coating after 310 hours salt spray test
112
4.26 EDX spectrum peaks of crack surface of sample N 113
4.27 Appearance of steel rope after being used for 3.5 years: (a) 117
xviii
construction of rope, (b) whole appearance of rope, (c)
appearance of IWRC, and (d) appearance of SC and RC
after dismantling
4.28 Appearance of the wire of steel rope strand after being used
for 3.5 years; (a) appearance of wires of S1 and S2, (b)
appearance of wires of S3, (c) appearance of wires of S4,
(d) appearance of wires of S5, and (e) appearance of wires
of S6
118
4.29 Corrosion rate of steel rope as a function of wire position
after being used for 3.5 years
120
4.30 Chloride content of wire surface according to wire position
after being used for 3.5 years
120
4.31 Cross-sections of wires in SC and RC strands after service
for 3.5 years
123
4.32 Cross-sections of R1 wire of IWRC after service for 3.5
years: (a) corrosion progressed along the interface between
the Zn-Fe alloy layer and substrate steel base, (b) corrosion
propagated inside the steel matrix resulting in corrosion pits,
(c) all Zn coatings were removed due to corrosion, and (d)
some surface areas still had Zn coating on the surface
125
4.33 Contact part of corrosion of R1 wire of IWRC after service
for 3.5 years
126
4.34 Cross-sections of S4 wires of IWRC after service for 3.5
years
127
4.35 FESEM image of contact part of corrosion of S4 wire of
IWRC after service for 3.5 years: (a) crevice corrosion and
pitting, (b) crevice corrosion and pitting, and (c) severe
pitting
128
4.36 Cross-section of wires of the rope strand after service for
3.5 years
129
4.37 FESEM images of corrosion morphology of wire rope
strands after service for 3.5 years
130
4.38 FESEM image of the cross-section of fretting of R1 of 131
xix
IWRC RC
4.39 FESEM image of cross-section of–0.5wt%Mg–0.5wt%Al
alloy coating sample
140
4.40 FESEM micrograph and EDX results of the first layer of Zn
– 0.5wt%Mg – 0.5wt% Al alloy coating
141
4.41 FESEM micrograph and EDX results of the second layer of
Zn – 0.5wt%Mg – 0.5wt% Al alloy coating
142
4.42 FESEM micrograph of Zn-0.5wt% Mg-0.5wt% Al alloy
coating after reducing the alloy thickness of the first pure
galvanizing process
143
4.43 FESEM micrograph and EDX results of third layer of Zn-
0.5wt% Mg-0.5%wt Al alloy coating
144
4.44 FESEM image and EDX analysis of surface of Zn-0.5wt%
Mg-0.5wt% Al alloy coating
145
4.45 FESEM image of surface of Zn-1.0wt% Mg-1.0wt% Al
alloy coating
146
4.46 FESEM micrograph and EDX results of first layer of Zn-
1.0wt% Mg-1.0wt% Al alloy coating
147
4.47 FESEM image and EDX results of second layer of Zn-
1.0wt% Mg-1.0wt% Al alloy coating
148
4.48 FESEM image and EDX results of third layer of Zn-1.0wt%
Mg-1.0wt% Al alloy coating
149
4.49 FESEM image and EDX results of surface of Zn-1.0wt%
Mg-1.0wt% Al alloy coating
150
4.50 FESEM micrograph of Zn-2.0wt% Mg-2.0wt% Al alloy
coating
151
4.51 FESEM of the first layer of Zn-2.0wt% Mg-2.0wt% Al
alloy coating and EDX results
151
4.52 FESEM image and EDX analysis of second layer of Zn-
2.0wt% Mg-2.0wt% Al alloy coating
152
4.53 FESEM image and EDX results of third layer of Zn-2.0wt%
Mg-2.0wt% Al alloy coating
153
4.54 FESEM image and EDX results of surface layer of Zn- 154
xx
2.0wt% Mg-2.0wt% Al alloy coating
4.55 FESEM image of surface layer of Zn-3.0wt% Mg-2.0wt%
Al alloy coating
155
4.56 FESEM image and EDX results of first layer of Zn-3.0wt%
Mg-2.0wt% Al alloy coating
156
4.57 FESEM image and EDX results of second layer of Zn-
3.0wt% Mg-2.0wt% Al alloy coating: (a) second layer, (b)
enlargement of second layer of (a) and EDX analysis
157
4.58 FESEM image and EDX results of the third layer of the Zn-
3.0wt% Mg-2.0wt% Al alloy coating: (a)&(b) third layer,
(c) enlargement of third layer of (a) and EDX results
159
4.59 FESEM image and EDX results of the fourth layer of the
Zn-3.0wt% Mg-2.0wt% Al alloy coating
160
4.60 FESEM image of the surface layer of Zn-3.0wt% Mg-
6.0wt% Al alloy coating
161
4.61 FESEM image and EDX results of first layer of Zn-3.0wt%
Mg-6.0wt% Al alloy coating
162
4.62 FESEM image and EDX results of second layer of Zn-
3.0wt% Mg-6.0wt% Al alloy coating
163
4.63 FESEM images and EDX results of the third layer of the
Zn-3.0wt% Mg-6.0wt% Al alloy coating: (a) third layer and
EDX analysis, and (b) magnified view of the third layer
164
4.64 FESEM image and EDX results of fourth layer of Zn-
3.0wt% Mg-6.0wt% Al alloy coating
165
4.65 FESEM image of surface layer of Zn-5.0wt% Mg-5.0wt%
Al alloy coating
166
4.66 FESEM image and EDX results of first layer of Zn-5.0wt%
Mg-5.0wt% Al alloy coating
167
4.67 FESEM image and EDX results of second layer of Zn-
5.0wt% Mg-5.0wt% Al alloy coating
168
4.68 FESEM image of the third layer of the Zn-5.0wt% Mg-
5.0wt% Al alloy coating
169
4.69 FESEM image of fourth layer of Zn-5.0wt% Mg-5.0wt% Al 170
xxi
alloy coating
4.70 FESEM micrographs of Zn-0.5wt% Mg-0.5wt% Al ingot
(a) whole phases, (b) magnified view of Eutectic binary
phase
171
4.71 FESEM microstructure of alloy ingot: (a) Zn-1.0wt% Mg-
1.0wt% Al ingot, (b) Zn-2.0wt% Mg-2.0wt% Al ingot, (c)
Zn-2.0wt% Mg-3.0wt% Al ingot
173
4.72 FESEM micrograph of Zn-5.0wt% Mg-5.0wt% Al ingot (a)
Whole phases (b) magnified view of ternary eutectic phase
174
4.73 FESEM micrograph of Zn-3.0wt% Mg-6.0wt% Al ingot 175
4.74 Corrosion rate versus magnesium and aluminum content of
alloy coating (Polarization/Tafel)
177
4.75 FESEM micrograph and EDX results of corrosion product
of pure zinc coating after 266 hours salt spray test
179
4.76 FESEM micrograph and EDX analysis of corrosion product
of Zn-Al coating after 720 hours salt spray test
180
4.77 FESEM micrograph and EDX results of Zn-0.5wt% Mg –
0.5wt% Al alloy coating before salt spray test
182
4.78 FESEM micrographs of corrosion products of Zn-0.5wt%
Mg-0.5wt% Al alloy coating after 3,144 hours exposure to
salt spray test
183
4.79 XRD analysis of corrosion product of Zn-0.5wt% Mg–
0.5wt% Al alloy coating after 3,144 hours exposure salt
spray test
184
4.80 FESEM microstructure of coating of Zn-0.5wt% Mg –
0.5wt% Al alloy coating before and after 3,144 hours salt
spray test
185
4.81 FESEM micrograph of the whole layer containing the thick
part of the Zn-0.5wt% Mg – 0.5wt% Al alloy coating after
3,144 hours exposure to salt spray testing
187
4.82 FESEM micrograph and EDX results of the top and middle
layers of the thick coating of the Zn-0.5wt% Mg–0.5wt% Al
alloy coating after 3,144 hours of salt spray +2 years
188
xxii
atmosphere exposure
4.83 FESEM micrograph and EDX analysis of first layer of thick
coating of Zn-0.5wt% Mg–0.5wt% Al alloy coating after
3144 hours exposure in salt spray +2years atmosphere
exposure
189
4.84 FESEM micrograph and EDX results of first layer of Zn-
0.5wt% Mg – 0.5wt% Al alloy coating after 3144 hours salt
spray +2years atmosphere exposure
190
4.85 FESEM microstructure of 3.83 mm wire drawn after pure
Zn coating
193
4.86 FESEM microstructure of 3.83 mm wire drawn after
the Zn-0.5wt% Mg – 0.5wt% Al alloy coating
193
xxiii
LIST OF ABBREVATIONS
CPS - Counts per second
CR - Corrosion rate
DLP - Direct in line patenting
EG - Electro galvanized
EDX - Energy Dispersive X-Ray Spectroscopy analyzer
EIS - Impedance spectra test
FESEM - Field Emission Scanning Electron Microscope
FPSO - Floating production storage and offloading
HDG - Hot dip galvanizing
HDPE - High density polyethylene
ICP-MS - Inductively Coupled Plasma Mass Spectrometry
ICP-OES - Inductively Coupled Plasma Emission Spectrometry
IWRC - Independent Wire Rope Core
LPD - Lead patenting process
mm - Millimeter
mm/y - Millimeter per year
N/mm2 - Newton per millimeter square
PVD - Physical vapour deposition
RC - Rope core (strand of IWRC)
SC - Core strand
SCE - Saturated calomel electrode
SPM - Single point moorings
T-T fatigue - Tension-tension fatigue
XRD - X-ray diffraction
α - Entrance angle
CHAPTER 1
INTRODUCTION
1.1 Background of the Research
The global offshore oil industry is expected to continue to increase in the
coming years, driven by the depleting onshore reserves and the discovery of new
large offshore reserves. Oil production in deep and ultra-deep waters has
significantly helped to advance new technologies. However, in exploring oil at
depths beyond 1500 meters, steel wire ropes experience many challenges which stem
from the sheer weight of the mooring system [1]. As water depth increases,
conventional all-steel spread mooring systems show a number of limitations, both in
operation and on the environment [2]. Such limitations include a lower restoring
efficiency, high proportion of tether strength consumed by the vertical components of
line tension, reduced pay-load of the vessel, and large mooring radius and sea-floor
footprint [2]. The weight penalty of steel wire also increases rapidly with water depth
and has become a significant cost driver for water depths beyond 2000 meters [3].
2
The obvious solution to these limitations is to avoid the weight penalty. There
are two possible ways to achieve this: (1) use lightweight materials such as fiber
ropes, or (2) increase the strength of steel rope so that it can be made thinner. There
are several problems that must be solved if fiber rope is to be used as a substitute for
steel wire rope: low axial stiffness that causes rope elongation with load, low
adhesive wear and tear resistance, low fatigue life when subjected to constant cyclic
bending due to damage occurring during heave compensation modes, internal heat
buildup, very low and variable coefficient of friction due to rope coating,
contamination and temperature. Therefore, steel wire rope is still effective for use in
mooring line components in deep water. However, further strengthening of steel wire
is required to overcome the weight penalty. Strengthening of steel wire can be
achieved by increasing carbon content, adding alloying elements and increasing cold
work [4-11]. A considerable amount of work has been carried out on micro-alloyed
steel in the past years, particularly involving chromium, manganese and
molybdenum additions [4-9]. The use of carbon contents up to 0.92% has been
shown as having potential for enhancing the strength of rods for roping applications
[10-11]. However, little work has been done towards improving the fatigue life and
corrosion resistance of steel wire ropes for offshore industry having carbon contents
higher than 0.92%. One of the fundamental problems is that there is the limit to
increase the strength of steel wire because the strength of the patented wire is
increased, but drawing amount is reduced with increasing carbon content. Another
problem is that it is difficult to meet the fatigue characteristics due to the
embrittlement that originates from cementite dissolution. Furthermore, the
mechanism of embrittlement is still not clear, since the mechanism of cementite
decomposition has been discussed without a common consensus being reached [12].
In the process of strengthening, the marine environmental factors should also
be considered because the effect of the marine environment on the fatigue life of the
ropes increases rapidly with the depth of seawater. Moreover, higher tensile strength
steels are more susceptible to the environment [13, 15]. Steel wire rope suffer
degradation by stress corrosion and fretting, particularly ropes used in mooring at sea.
Fretting can be exacerbated not only by the presence of such an aggressive
3
environment such as seawater, but also by the continuous cyclic loading through
wave movement over the length of the rope during its entire lifetime [14]. These
factors result in a significant reduction in the life of the ropes. Thus, the challenge is
to develop ropes with increased strength, and at the same time to reduce the harmful
effects of environmental factors.
In the present research, an investigation has been conducted to determine the
types of degradation that may occur when high strength steel ropes are used for
mooring lines, and to explore a new coating technology and steel strengthening
process to overcome these degradations.
1.2 Problem Statement
To fulfill the increased demand in the mooring application, new technology
development should be made in three areas: high strengthening technology, good
fatigue property in high strength steels, and excellent corrosion resistant coating
technology. However, several problems associated with these developments exist:
a) Since the effect of the marine environment on the fatigue life of ropes
increases rapidly with the depth of seawater, higher tensile strength steels have a
shorter life span, owing to their increased susceptibility to the environment. The
mechanism is still not clear and there is no method to date on how to solve such a
problem.
b) Steel wire rope is greatly affected by fretting-induced corrosion, which
becomes more severe with increasing sea water depth. However, there is a lack of
4
understanding on the effect of increasing the tensile strength on fretting-induced
corrosion and also on the methods to reduce this fretting harmful effect.
c) It is well-known that anti-corrosion products contribute to corrosion
inhibition, but in the case of severe fretting, their role is reduced because the anti-
corrosion material is easily removed. Until today, there is no research on how to
reduce this fretting harmful effect, or development of a new coating technology to
produce tough anti-corrosion products having high fretting resistance with increased
exposure to sea water.
d) It is well established that the life span of mooring ropes is primarily
dependent on the corrosion resistance of the zinc coating, but very few attempts were
made to develop a new coating capable of increasing the corrosion resistance of steel
wire ropes. This research is aimed to develop high tensile steel rope (2,150-2,250
MPa) with good corrosion resistance.
1.3 Objectives of the Research
To meet the current technology trend of offshore oil and gas production
facilities, development of ropes having lighter characteristics and longer life span is
required.
Therefore, the main objectives of this research are to develop steel ropes with
high tensile strength and excellent corrosion resistance. The specific objectives are:
1. To investigate the effect of composition on strength and corrosion
resistance of galvanized wire.
2. To investigate the degradation mechanism of high tensile strength (2,150 -
5
2,250 MPa) galvanized steel rope in sea water.
3. To develop a Zn-Al-Mg ternary alloy coating to enhance the corrosion
resistance (3,000 salt spray hours) of steel ropes.
1.4 Scope of Work
In order to increase the strength of steel wires, used in the oil and gas
industries, above 2,150 MPa and corrosion resistance over 3,000 salt spray hours, the
study concentrates mainly on the following:
1. Enhancing the fatigue property and corrosion resistance of galvanized
steel wire through control of steel chemical composition by varying the carbon
content (0.87-0.98wt%) and alloying elements of Cr (0.58-0.60wt%) and Si
(0.2~1.3wt%). This phase of research focuses on investigating:
a) Tensile strength, torsion and delamination of galvanized steel wire
b) Fatigue property and fracture behaviour of galvanized steel strand
c) Formation of Zn-Fe alloy layer during hot dip galvanizing and its effects
on the corrosion resistance of steel wire
2. Degradation mechanism of galvanized steel rope in sea water. This phase
consists of examining:
a) The effect of fretting and contact pressure among wires on the corrosion
behavior of exposed steel ropes
b) The corrosion behaviour based on wire position in the rope
3. Corrosion protection of rope in sea water by using newly developed zinc
alloy coating. This phase of research looks at:
a) The effects of Mg (0.5-5.0wt%) and Al (0.5-6.0wt%) contents on coating
microstructure
b) The effects of Mg and Al contents in the Zn alloy coating on the
corrosion behaviour and corrosion product characteristics
199
process, (c) corrosion product having good adhesion, which improves resistance
against fretting.
7. The lowest corrosion rate was obtained in the Zn-Mg-Al alloy coating
having 1.0~3.0wt% Mg and Al content. Even by addition of a small amount of Mg
and Al by 0.5wt%, the corrosion resistance, similar to the Zn-3.0wt%Mg-6.0wt%Al
alloy coating was obtained. Over that wt.%, the improvement effect of corrosion
resistance was not observed. The Zn-0.5wt% Mg-0.5wt% Al coating had an excellent
corrosion resistance (3,144 hours in salt spray), which was 12 times higher than the
pure Zn coating. It might be attributed to simonkolleite (Zn5 (OH)8Cl2 • H2O) found
on the surface as the main element of the corrosion product.
8. The Zn-Mg-Al Alloy coating produced by the two-step galvanizing
processes had very good corrosion resistance and fretting resistance due to the
following reasons: (a) multi-layers have several different alloy phases. These alloy
phases exert a synergistic effect in improving corrosion and fretting resistance, and
(b) no cracks inside the coating during the coating and drawing process.
5.2 Recommendation for Future Work
As described previously, since rope degradation was the dominating factor for
mooring, caused by fretting and corrosion, the investigation of the Zn-Al-Mg alloy
coated rope life span is required.
200
REFERENCES
1. Klaoudatos, L., Station Keeping for Deepwater Mobile Offshore Drilling
Units: An Economic and Operational Perspective. 2006: Erasmus University.
2. Del Vecchio, C., et al., Deep Water Mooring Systems Using Fiber Ropes.
Composite Materials for Offshore Operations, 1999. 2: p. 255-264.
3. Torben, S., et al., Fiber Rope Deployment System And Rope Management
Process, in The Eighteenth International Offshore and Polar Engineering
Conference. 2008, International Society of Offshore and Polar Engineers:
Vancouver, Canada.
4. Gh.Ali Nematollahi, Multiscale description of carbon-supersaturated ferrite
in severely drawn pearlitic wires. Actra Materialia, 2016. 111 : p.321-334.
5. Xiaodan Zhang, Andy Godfrey,Microstructure and strengthening mechansim
in cold-drawn pearlitic steel wire. Actra Materialia, 2011. 59: p.3422-3430.
6. Franklin, J., et al., Heat Treatment and Alloying of Drawn Wires. Wire
Industry, 1980. 47(563): p. 967-972.
7. Nishimura, T., T. Fujiwara, and Y. Tanaka, Multi-Wire Electrical Discharge
Slicing for Silicon Carbide. Wire Journal, 1980. 13(10).
8. Mikulec, Z., Drawing of Rapidly-Cooled Wire Microalloyed With Vanadium.
Hutnik(Prague), 1980. 30(5): p. 189-193.
9. Mazzucato, F., A. Mascanzoni, and A. Guerrieri, Effects of manganese,
chromium, and molybdenum on the isothermal transformation of austenite in
eutectoid steels. Wire J. International, 1982. 15(10): p. 74–79.
10. Stacey, A.G., Pearlitic Steels with Si and V Additions. Met. & Mat. Trans. A,
1987. 3: p. 706-711.
11. A, Lamontagne,V. Massardier,Evolution of carbon distribution and
mechanical properties during the static strain ageing of heavily drawn
pearlitic steel wires. Material Science & Engineering, 2016, A 667: p.
115-124
12. Takahashi, J., et al., Change in carbon state by low-temperature aging in
201
heavily drawn pearlitic steel wires. Acta Materialia, 2012. 60(1): p. 387-395.
13. K.j. Miller and R. Akid, The application of microstructural fracture
mechanics to various metal surface states. Material Science, 1997. 33(1): p.
1-19.
14. Chaplin, C., 33rd
Annual Offshore Technology Conference (OTC) May 2000.
12173 ; Vol 2, p. 837-844.
15. Chaplin, C. and A. Potts, Wire rope offshore–a critical review of wire rope
endurance research affecting offshore applications-Offshore Technology
Report OTH 91 341. 1991, HMSO UK.
16. Xiaohua Hu, Paul Van Houtte and Martin Liebeherr, Modeling work
hardening of pearlitic steels by phenomenological and Taylor-type
micromechanical models. Actra Materialia, 2006, volume 54, issue 4 : p.
1029-1040.
17. Europe, N.D., Floating production system JIP FPS mooring integrity. 2006,
Research report 444 prepared for the Health and Safety Executive (HSE).
18. Toshihiko Takahashi, Strengthening of steel wire for tire cord.Nippon steel
technical report , 1995. No.64: p. 45-499.
19. Shipley, E., High-Strength Steel Wire. High Strength Steels, 1962: p. 93-99.
20. Leslie, W. and G. Rauch, Precipitation of carbides in low-carbon Fe-AI-C
alloys. Metallurgical Transactions A, 1978. 9(3): p. 343-349.
21. Han, K., G. Smith, and D. Edmonds, Pearlite phase transformation in Si and
V steel. Metallurgical and Materials Transactions A, 1995. 26(7): p. 1617-
1631.
22. Kaiso, M., et al., Mechanical Properties of Drawn Hypereutectoid Steel Wires.
Wire Journal International, 2002. 35(2): p. 116-121
23. Ochiai, I., et al., Direct-Patented High-Strength Steel Wire Rod Strengthened
by Silicon. Wire Journal International 1933: p. 72-85.
24. Tashiro, H., et al., Alloying effect on the Strength of Directly Annealed Steel
Wire rods. Transactions ISIJ, 1988. 28: p. 29.
25. Han, K., et al., Effects of vanadium additions on microstructure and hardness
of hypereutectoid pearlitic steels. Materials Science and Engineering: A, 1995.
190(1): p. 207-214.
26. Nicholson, M., Solubility of boron in Fe3C and variation of saturation
202
magnetization, Curie temperature, and lattice parameter of Fe3 (C, B) with
composition. Trans-AIME (J. Metals), 1957. 209: p. 1-6.
27. Taleff, E.M., et al., Pearlite in ultrahigh carbon steels: Heat treatments and
mechanical properties. Metallurgical and Materials Transactions A, 1996.
27(1): p. 111-118.
28. Embury, J. and R. Fisher, The structure and properties of drawn pearlite.
Acta Metallurgica, 1966. 14(2): p. 147-159.
29. Dewey, M. and G. Briers, Structure of heavily cold drawn eutectoid steel.
Iron Steel Inst J, 1966. 204(2): p. 102-103.
30. Puttick, V., The Structure, Deformation and Fracture of Perlite. J. Iron Steel
Inst, 1957. 185(2): p. 161-176.
31. Fickering, F.B., Carbide precipitates in steels. Iron & Steel, 1965. 38: p. 110.
32. Takahashi, T. and M. Nagumo, Flow stress and work-hardening of pearlitic
steel. Transactions of the Japan Institute of Metals, 1970. 11(2): p. 113-119.
33. Kaldor, M., About the deformation of pearlite. Acta Metallurgica, 1962. 10(9):
p. 887.
34. Langford, G. and M. Cohen, Strain hardening of iron by severe plastic
deformation. ASM Trans Quart, 1969. 62(3): p. 623-638.
35. Lee, S., D. Ko, and B. Kim, Pass schedule of wire drawing process to prevent
delamination for high strength steel cord wire. Materials & Design, 2009.
30(8): p. 2919-2927.
36. Nishida, S., A. Yoshie, and M. Imagumbai, Work Hardening of
Hypereutectoid and Eutectoid Steels during Drawing. ISIJ international, 1998.
38(2): p. 177-186.
37. Maruyama, N., T. Tarui, and H. Tashiro, Atom probe study on the ductility of
drawn pearlitic steels. Scripta materialia, 2002. 46(8): p. 599-603.
38. Languillaume, J., G. Kapelski, and B. Baudelet, Cementite dissolution in
heavily cold drawn pearlitic steel wires. Acta Materialia, 1997. 45(3): p.
1201-1212.
39 Watté, P., et al., Strain ageing in heavily drawn eutectoid steel wires. Scripta
materialia, 1996. 34(1): p. 89-95.
40. Hono, K., et al., Cementite decomposition in heavily drawn pearlite steel wire.
Scripta materialia, 2001. 44(6): p. 977-983.
203
41. Gridnev, V. and V. Gavrilyuk, Cementite Decomposition in Steel During
Plastic Deformation.(Review). Phys. Met.(USSR), 1982. 4(3): p. 531-551.
42. Bushan (2011) Continuous Hot-Dip Galvanizing versus General (Batch)
Galvanizing. Galv InfoNote 2-3.
43. Skenazi, A.F., et al. Zinc Coated Steels. in Proceedings of the 1st
International Conference on Zinc Coated Steel. 1985. Munich, London: Zinc
Development Association.
44. Jordan, C. and A. Marder, Fe-Zn phase formation in interstitial-free steels
hot-dip galvanized at 450° C: Part I 0.00 wt% Al-Zn baths. Journal of
Materials Science, 1997. 32(21): p. 5593-5602.
45. Sandelin, R.W., Galvanizing Characteristics of Different Types of Steels. Wire
and wire product, 1940. 14: p. 655-676.
46. Sandelin, R.W., Galvanizing Characteristics of Different Types of Steels. Wire
and wire product, 1940. 14: p. 721-749.
47. Sandelin, R.W., Galvanizing Characteristics of Different Types of Steel. 1941:
American Hot Dip Galvanizers Association.
48. Sandelin, R., Modern Trends in Steel as Affecting Hot Dip Galvanizing.
American Hot Dip Galvanizers Association, Washington, DC, 1963.
49. Habraken, L. Influence of Additional Alloying Elements on Corrosion
Resistance of Hot Dip Galvanised Steels. in Proceedings of 12th
International Galvanizing Conferencep 1979. Paris: Zinc Development
Association.
50. Guttman, H. and P. Niessen, Reactivity of silicon steels hot-dip galvanizing.
Canadian Metallurgical Quarterly, 1972. 11(4): p. 609-615.
51. Mackowiak, J. and N. Short, Metallurgy of galvanized coatings. International
metals reviews, 1979. 24(1): p. 1-19.
52. Horstmann, D. and F. Peters, The reaction between iron and zinc. London:
Zinc Development Association, 1978.
53. Kozdras, M. and P. Niessen, Silicon-induced destabilization of galvanized
coatings in the sandelin peak region. Metallography, 1989. 22(3): p. 253-267.
54. Reumont, G., P. Perrot, and J. Foct. Validation of the Modelling of a Solid-
Liquid Reaction by A Solid-Vapor Reaction. in MRS Proceedings. 1994:
Cambridge Univ Press.
204
55. Belfrage, S. and P. Ostrom. Hot Dip Galvanising in a Zinc Melt Containing
0.15% Nickel. in Proceedings of the 15th International Conference on Hot
Dip Galvanising. 1988.
56. Sokolowski, R. Edmund Husserl and the Phenomenological Tradition Essays
in Phenomenology. in Proceedings of 15th International Galvanizing
Conference. 1988. Rome: ZDA, GE4.
57. Krepski, R.P. Nickel-Based Pretreatment to Solve the Silicon Steel. in
Proceedings of 15th International Galvanizing Conference (1988). 1988.
Rome: Zinc Development Association, London.
58. Reumont, G., P. Perrot, and J. Foct, Thermodynamic study of the galvanizing
process in a Zn–0.1% Ni bath. Journal of Materials Science, 1998. 33(19): p.
4759-4768.
59. Chen, Z., et al., Technigalva and other developments in batch hot-dip
galvanizing. JoM, 1992. 44(1): p. 22-26.
60. Porter, F.C., Zinc handbook: properties, processing, and use in design. 1991:
CRC Press.
61. Sebisty, J. and R. Palmer, Hot dip galvanizing with less common bath
additions. Hot Dip Galvanizing. Pergamon Press, New York, 1967, p. 235-
265, 1967.
62. Reumont, G., J. Foct, and P. Perrot. New possibilities for the galvanizing
process: The addition of manganese and titanium to the zinc bath. in
Nineteenth International Galvanizing Conference,, Intergalva. 2000.
63. Adams, G. and J. Zervoudis, A new alloy for galvanizing reactive steel.
Proceedings Intergalva, 1997.
64. Chaplin, C., A. Potts, and A. Curtis. Degradation of wire rope mooring lines
in SE Asian waters. in Offshore Asia Conference. 2008. Kuala Lumpur.
65. API, R.P.S., Design and Analysis of Station Keeping Systems for Floating
Structures. 2005, American Petroleum Institute.
66. DNV-OS-E301, Position Mooring, in Standard Offshore. 2004: Det Norske
Veritas.
67. Suzumura, K. and S.-i. Nakamura, Environmental factors affecting corrosion
of galvanized steel wires. Journal of materials in civil engineering, 2004.
16(1): p. 1-7.
205
68. Ropes, B., ed. Ropes for deep water moorings. 1979, British Ropes
Publication 1156.
69. Chaplin, C.R. and A.E. Potts, Wire Rope Offshore-A Critical Review of Wire
Rope Endurance Research Affecting Offshore Applications. 1991.
70. Swan, J. The Corrosion Resistance of Wire Products in Marine Applications.
in Offshore Technology Conference. 1970: Offshore Technology Conference.
71. Husain, Z. and R. Cottis, The Influence of Seawater Corrosion on the Fatigue
Strength of Steel Wire Rope. Fatigue of Engineering Materials and Structures.,
1986. 2: p. 387-392.
72. Thorpe, T., A. Rance, and D. Silvester, The fatigue of electrogalvanised wire
used in the manufacture of wire ropes. Report by the Materials Development
Division. Atomic Energy Research Establishment (AERE), Harwell, UK,
1985.
73. Thorpe, T. and A. Rance. The Tensile Fatigue of Wire Rope: A New Approach.
in Offshore Technology Conference. 1983: Offshore Technology Conference.
74. Pearson, B. and R. Waterhouse. The fretting corrosion in sea water of
materials used in off-shore structures. in International Congress on Metallic
Corrosion. 1984.
75. Pearson, B. and R. Waterhouse, The fretting of steels in seawater. Tribology
Offshore, 1984: p. 49-60.
76. Waterhouse, R., B. Pearson, and R. Smallwood. The effectiveness of zinc
galvanised coatings in reducing fretting corrosion damage in steel ropes. in
Proc. 01PEEC Round Table Conf. 1985: National Engineering Laboratory
Glasgow.
77. Waterhouse, R. and D. Taylor, Fretting fatigue in steel ropes. Lubric. Eng.,
1971. 27(4): p. 123-127.
78. Prosek, T., et al., Corrosion mechanism of model zinc–magnesium alloys in
atmospheric conditions. Corrosion Science, 2008. 50(8): p. 2216-2231.
79. Volovitch, P., et al., Understanding corrosion via corrosion product
characterization: II. Role of alloying elements in improving the corrosion
resistance of Zn–Al–Mg coatings on steel. Corrosion Science, 2011. 53(8): p.
2437-2445.
80. Ogle, K., et al., Localized electrochemical methods applied to cut edge
206
corrosion. Journal of the Electrochemical Society, 2000. 147(10): p. 3654-
3660.
81 Pelerin, S., Corrosion mechanism and reinforced protection of hot-dipped
coated steel wire in seawater, in Mechanical Engineering. 1982, Northeastern
University: London.
82. Allegra, L. and J.C. Zoccola, Intergranular zinc embrittlement and its
inhibition by phosphorus in 55 pct Al-Zn-coated sheet steel. Mater. Perform.,
1983. 5(22).
83. Townsend, H. and J. Zoccola, Atmospheric corrosion resistance of 55% Al–
Zn coated sheet steel: 13-year test results. Materials Performance, 1979.
18(10): p. 13-20.
84. Tsuru, T., K.-I. Tamiya, and A. Nishikata, Formation and growth of micro-
droplets during the initial stage of atmospheric corrosion. Electrochimica
acta, 2004. 49(17): p. 2709-2715.
85. Tsujimura, T., A. Komatsu, and A. Andoh. Influence of Mg content in coating
layer and coating structure on corrosion resistance of hot-dip Zn–Al–Mg
alloy coated steel sheet. in Proceedings of the Galvatech. 2001.
86. Kawafuku, J., et al., Properties of zinc alloy coated steel sheets obtained by
continuous vapor deposition pilot-line. 1991, SAE Technical Paper.
87. Morishita, M., et al., Improvement in the Electrodeposition of Corrosion
Resistance of Zinc-plated Magnesium from a Molten Salt. ISIJ international,
1996. 36(6): p. 714-719.
88. Morishita, M., K. Koyama, and Y. Mori, Inhibition of anodic dissolution of
zinc-plated steel by electrodeposition of magnesium from a molten salt. ISIJ
international, 1997. 37(1): p. 55-58.
89. Morishita, M., K. Koyama, and Y. Mori, Self-healing ability of zinc-plated
steel coated with magnesium electrodeposited from a molten salt. Materials
Transactions, JIM, 1997. 38(8): p. 719-723.
90. Hausbrand, R., M. Stratmann, and M. Rohwerder, Delamination resistant
zinc alloys: Simple concept and results on the system zinc-magnesium. Steel
research international, 2003. 74(7): p. 453-458.
91. Vlot, M., et al. MagiZincTM: a new generation of hot-dip galvanised
products. in Proceedings of the Galvanized Steel Sheet Forum, ILZRO and
207
IZA, Duesseldorf, Germany. 2006.
92. Koll, T., et al., Properties and potential applications of novel ZnMg alloy
coatings on steel sheet. Revue de Métallurgie, 2004. 101(7-8): p. 543-550.
93. Townsend, H., Technical Note: On the Effects of Magnesium on the
Atmospheric Corrosion Resistance of Galvanized Sheet Steel. Corrosion,
1988. 44(4): p. 229-230.
94. Dagbert, C., et al., Effect of Additive Elements in Galvanizing Baths on
Atmospheric Corrosion Resistance of Galvanized Steels. Materiaux et
Techniques(Paris), 1990. 78(7): p. 11-16.
95 Zhang, X., Corrosion and Electrochemistry of Zinc. New York, Plenum Press.,
1996.
96. Kurosaki, M., et al., Zn-Al-Mg-Si-alloy plated steel product having excellent
corrosion resistance and method for preparing the same. 2003, Google
Patents.
97. Oh, M.S., et al., Molten zinc alloy plated steel strip having excellent
corrosion resistance and external surface and method for manufacturing
same. 2014, Google Patents.
98. Honda, K., W. Yamada, and K. Ushioda, Solidification structure of the
coating layer on hot-dip Zn-11% Al-3% Mg-0.2% Si-coated steel sheet.
Materials transactions, 2008. 49(6): p. 1395-1400.
99. Li, S., et al., Study on the Corrosion Mechanism of Zn-5Al-0.5 Mg-0.08 Si
Coating. Journal of Metallurgy, 2011. 2011.
100. Xu, H., Study on the Process and Anticorrosion Mechanism of Hot Dipping
Zn-Al-Mg Alloy Coating. 2009, ShanDong University, China: Jinan.
101. Schuerz, S., et al., Corrosion behaviour of Zn–Al–Mg coated steel sheet in
sodium chloride-containing environment. Corrosion Science, 2009. 51(10): p.
2355-2363.
102. Dutta, M., A.K. Halder, and S.B. Singh, Morphology and properties of hot
dip Zn–Mg and Zn–Mg–Al alloy coatings on steel sheet. Surface and
Coatings Technology, 2010. 205(7): p. 2578-2584.
103. Dutta, M. and S.B. Singh, Effect of strip temperature on the formation of an
Fe 2 Al 5 inhibition layer during hot-dip galvanizing. Scripta materialia, 2009.
60(8): p. 643-646.
208
104. Fontana, M.G., Corrosion engineering. 2005: Tata McGraw-Hill Education.
105. Prosek, T., et al., Corrosion properties of model Zinc-Magnesium alloys.7th
International Conference Zinc and Zinc alloy coated steel sheet, Galvatech
2007 Osaka Japan. p. 54-63.
106. Hausbrand, R., M. Stratmann, and M. Rohwerder, Corrosion of zinc–
magnesium coatings: Mechanism of paint delamination. Corrosion Science,
2009. 51(9): p. 2107-2114.
107. Tanaka, S., et al. The performance of Zn–Al–Mg–Si hot-dip galvanized steel
sheet. in Proceedings of the Galvatech. 2001.
108. Persson, D., et al., In situ infrared reflection spectroscopy studies of the initial
atmospheric corrosion of Zn–Al–Mg coated steel. Corrosion Science, 2013.
72: p. 54-63.
109. Schuerz, S., et al., Corrosion behaviour of Zn–Al–Mg coated steel sheet in
sodium chloride-containing environment. Corrosion Science, 2009. 51(10): p.
2355-2363.
110. Schürz, S., et al., Chemistry of corrosion products on Zn–Al–Mg alloy coated
steel. Corrosion Science, 2010. 52(10): p. 3271-3279.
111. Prosek, T., et al., Composition of corrosion products formed on Zn–Mg, Zn–
Al and Zn–Al–Mg coatings in model atmospheric conditions. Corrosion
Science, 2014. 86: p. 231-238.
112. Maalman, T.F.J., R. Bleeker, and M.J. Vlot, Steel sheet with hot dip
galvanized zinc alloy coating and process to produce it. 2014, Google Patents.
113. Feng, L., L. Shun, and Y. Honggang, Low-aluminum low-magnesium zinc-
aluminum-magnesium plated steel plate and method for producing same.
2013, Google Patents.
114. Yeung, Y.C.T. and Walton, J.M, Accelerated block tension fatigue testing wire
rope for offshore use. OIPEEC, 1985. NEL Glasgow.
115. Venkatesan, P. , Anand B. and Matheswaran, P., Influence of formazan
derivatives on corrosion inhibition of mild steel in hydrochloric acid medium,
Journal of chemistry, 2009. Vol. 6, No. S1, : p. 438-444.
116. Burstein, G.T., A century of Tafel's equation: A commemorative issue of
corrosion science, 2005. Vol. 47, Issue 12, : p. 2858-2870.
117. Nam, W.J., et al., Effect of interlamellar spacing on cementite dissolution
209
during wire drawing of pearlitic steel wires. Scripta materialia, 2000. 42(5): p.
457-463.
118. Song, H.R., E.G. Kang, and W.J. Nam, Effect of alloying elements on work
hardening behavior in cold drawn hyper-eutectoid steel wires. Materials
Science and Engineering: A, 2007. 449: p. 1147-1150.
119. Tarui, T., et al., Metallurgical design of ultra high strength steel wires for
bridge cable and tire cord. Metallurgy, Processing and Applications of Metal
Wires, 1996: p. 87-96.
120. Boyer, H.E., Metals handbook: Failure analysis and prevention. 1975:
American Society for Metals.
121. Eric M. Taleff, Pearlite in ultrahigh carbon steels: Heat treatments and
mechanical properties. Metallugical and material tractions A, 1996, Vol. 27,
Issue 1 : p. 111-118.
122. Shen, Y., et al., Fretting wear behaviors of steel wires under friction-
increasing grease conditions. Tribology International, 2011. 44(11): p. 1511-
1517.
123. Zhang, D., et al., Fretting wear behaviors of steel wires in coalmine under
different corrosive mediums. Wear, 2011. 271: p. 866-874.
124. Ge, S., R. Qu, and W. Xie, Reliability techniques for winders in mine. China
University of Mining and Technology, 1994.
125. McAdam Jr, D. Some Factors Involved in Corrosion and Corrosion-Fatigue
of Metals. in Proceedings. 1928.
126. Miller, K.J. and Akid, R., The Application of Microstructural Fracture
Mechanics to Various Metal Surface States.Proceedings Royal Society
London A, 1996. 452: p. 1411-1432.
127. Reumont, G., et al., The effects of an Fe–Zn intermetallic-containing coating
on the stress corrosion cracking behavior of a hot-dip galvanized
steel.Surface and Coatings Technology, 2001. 139(2–3): p. 265-271.
128. Foct, J., Relaxation of stresses by cracks in intermetallic coatings:
application to galvanizing. Scripta metallurgica et materialia, 1993. 28(1): p.
127-132.
129. Cardou, A. and C. Jolicoeur, Mechanical models of helical strands. Applied
Mechanics Reviews, 1997. 50: p. 1-14.
210
130. Wang, D., et al., Finite element analysis of hoisting rope and fretting wear
evolution and fatigue life estimation of steel wires. Engineering failure
analysis, 2013. 27: p. 173-193.
131. Jones, D.A., Principles and prevention of corrosion. 1992: Macmillan.
132. Odnevall, I. and C. Leygraf, Formation of NaZn 4 Cl (OH) 6 SO 4· 6H 2 O in
a marine atmosphere. Corrosion Science, 1993. 34(8): p. 1213-1229.
133. Ligier, V., et al., Formation of the main atmospheric zinc end products: NaZn
4 Cl (OH) 6 SO 4· 6H 2 O, Zn 4 SO 4 (OH) 6· nH 2 O and Zn 4 Cl 2 (OH) 4
SO 4· 5H 2 O in [Cl−][SO 4 2−][HCO 3−][H 2 O 2] electrolytes. Corrosion
Science, 1999. 41(6): p. 1139-1164.
134. Fujita, S. and H. Kajiyama, Quantitative analyses of crystalline compositions
of iron rust on automobiles under service conditions. ISIJ international, 2001.
41(3): p. 275-280.
135. Yadav, A., et al., Effect of Fe–Zn alloy layer on the corrosion resistance of
galvanized steel in chloride containing environments. Corrosion Science,
2007. 49(9): p. 3716-3731.
136. Mouanga, M., et al., Galvanic corrosion between zinc and carbon steel
investigated by local electrochemical impedance spectroscopy.
Electrochimica acta, 2013. 88: p. 6-14.
137. Morimoto, Y., et al., Excellent Corrosion-resistant Zn-Al-Mg-Si Alloy Hot-dip
Galvanized Steel Sheet" SUPER DYMA". Shinnittetsu Giho, 2002: p. 22-24.
138. Nishimura, K., K. Kato, and H. Shindo, Highly corrosion-resistant Zn-Mg
Alloy galvanized steel sheet for building construction materials. Nippon Steel
Technical Report, 2000. 81(0).
139. Shindo, H., et al., Developments and properties of Zn-Mg galvanized steel
sheet dymazinc have excellent corrosion resistance. Nippon steel technical
report. Overseas, 1999(79): p. 63-67.
140. Nishimura, K., et al. Microstructure and corrosion behaviour of Zn–Mg–Al
hot-dip galvanized steel sheet. in Proceedings of the Galvatech. 1998.
141. Shindo, H., K. Nishimura, and K. Kato. Anticorrosion in atmospheric
exposure of Zn–Mg–Al hot dip galvanized steel sheet. in Proceedings of the
Galvatech. 1998: p. 433-436.
142. Tsujimura, T., A. Komatsu, and A. Andoh. Influence of Mg content in coating
211
layer and coating structure on corrosion resistance of hot-dip Zn–Al–Mg
alloy coated steel sheet. in Proceedings of the Galvatech '01, International
Conference on Zinc and Zinc Alloy Coated Steel. 2001. Brussels, Belgium.
143. Komatsu, A., et al., Hot-dip Zn-Al-Mg coated steel sheet excellent in
corrosion resistance and surface appearance and process for the production
thereof. 1998, Google Patents.
144. Yao, C., et al., Effects of Mg content on microstructure and electrochemical
properties of Zn–Al–Mg alloys. Journal of Alloys and Compounds, 2015. 645:
p. 131-136.
145. De la Fuente, D., J. Castano, and M. Morcillo, Long-term atmospheric
corrosion of zinc. Corrosion Science, 2007. 49(3): p. 1420-1436.
146. Odnevall, I.and Leygraf, C., The formation of Zn4Cl2(OH)4SO4 . 5H2O in an
urban and an industrial atmosphere. Corrosion Science, 1994. 36(9): p.
1551-1559.
147. Hosking, N.C., et al., Corrosion resistance of zinc-magnesium coated steel.
Corrosion Science, 2007. 49(9): p. 3669-3695.
148. Volovitch, P., et al., Understanding corrosion via corrosion product
characterization: I. Case study of the role of Mg alloying in Zn-Mg coating
on steel. Corrosion Science, 2009. 51(6): p. 1251-1262.
149. Jönsson, M., D. Persson, and D. Thierry, Corrosion product formation during
NaCl induced atmospheric corrosion of magnesium alloy AZ91D. Corrosion
Science, 2007. 49(3): p. 1540-1558.
150. Thierry, D., et al., Corrosion protection and corrosion mechanisms of
continuous galvanized steel sheet with focus on new coating alloys. Galvatech
‘11, Genova, Italy [6]“ZM EcoProtect®-The innovative Coating”, brochure
of ThyssenKrupp Steel Europe AG, 2010.
151. Hausbrand, R., M. Stratmann, and M. Rohwerder, The physical meaning of
electrode potentials at metal surfaces and polymer/metal interfaces:
consequences for delamination. Journal of the Electrochemical Society, 2008.
155(7): p. C369-C379.
152. Diler, E., et al., Stability of ZnMgO oxide in a weak alkaline solution. Thin
Solid Films, 2012. 520(7): p. 2819-2823.
212
LIST OF PUBLICATIONS
1. M.H.Cho, S.Salleh, N.Ahmad, A.Ourdjini, E.Hamzah,Influence of Carbon
Content On The Mechanical Properties of Ultra-high Strength Of Coated
Steel Wire for Oil and Gas Industries. 2012: Journal Technology University
Technology Malaysia.
2. M.H.Cho, F.Mohamed, A.Ourdjini, E.Hamzah, Factors Affecting Fatigue
Behaviour Properties of Ultra-High Strength Steel Rope for Offshore Oil and
Gas Industry. Composite Materials for Offshore Operations, 2011. Offshore
Asia ConferenceKuala Lumpur.
3. M.H.Cho, Zinc alloy plated wire having excellent corrosion resistance,
filing no.: PCT /KR2025/011826, 제 15-153249호.