stainless steel cladding by advanced submerged arc welding
TRANSCRIPT
STAINLESS STEEL CLADDING BY ADVANCED SUBMERGED ARC WELDING PROCESS
HARI OM
DEPARTMENT OF MECHANICAL ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY DELHI
JULY 2013
© Indian Institute of Technology Delhi (IITD), New Delhi, 2013
STAINLESS STEEL CLADDING BY ADVANCED
SUBMERGED ARC WELDING PROCESS
by
HARI OM
DEPARTMENT OF MECHANICAL ENGINEERING
Submitted
in fulfilment of the requirements of the degree of
Doctor of Philosophy
to the
INDIAN INSTITUTE OF TECHNOLOGY DELHI
JULY 2013
i
CERTIFICATE
This is to certify that the thesis entitled “Stainless Steel Cladding by Advanced Submerged
Arc Welding Process” being submitted to the Indian Institute of Technology Delhi by Mr.
Hari Om is worthy of consideration for the award of the degree of Doctor of Philosophy and
is a record of the original bona fide research work carried out by him under my guidance and
supervision.
To the best of my knowledge, this work in part or full has not been presented to any other
university or institute for the award of any degree / diploma.
Prof. Sunil Pandey, Ph. D.
Department of Mechanical Engineering
Indian Institute of Technology Delhi
Hauz Khas, New Delhi-110016, India.
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ACKNOWLEDGEMENTS
First and foremost, I admire God, the almighty for providing me this opportunity and granting
me the capability to proceed successfully. I am ever grateful to God, the Creator and the
Guardian, and to whom I owe my very existence.
I express my deep sense of gratitude and indebtedness to my mentor and supervisor Prof.
Sunil Pandey of the Department of Mechanical Engineering, Indian Institute of Technology
Delhi for providing unreserved guidance, inspiring discussions and constant supervision
throughout my research work. His continued scholarly advice, timely help and constructive
criticism at various stages and conscientious efforts have greatly enriched the research work.
His indefatigable energy to work, inexhaustible knowledge and rich experience were highly
instrumental in converting my research into meaningful conclusion. It has been a benediction
for me to spend many opportune moments under the guidance of the perfectionist at the acme
of professionalism.
I sincerely acknowledge Prof. P. V. Rao, and Dr. P. M. Pandey, Department of Mechanical
Engineering, and Prof. D. K. Sehgal, Department of Applied Mechanics, the members of the
‗Students Research Committee‘ (SRC) at the Indian Institute of Technology Delhi, for their
incessant encouragement and valuable suggestions. I am highly thankful to Dr. S. Aravindan,
Department of Mechanical Engineering, for his appreciable guidance and inspiring
encouragement.as in-charge of welding research laboratory, He has been a great help in
finalization of various purchases required for the research work. .
I extend thanks to Mr. A. Siva Kumar, Technical Superintendent, for his hearty cooperation
during initial years of my research work. My whole hearted thanks go to Mr. Ayodhya Prasad
and Mr. Sunil Kumar Mishra, Welding Research Laboratory for their cooperation and
conscientious effort to overcome various hurdles met during the experimental work.
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I gracefully acknowledge with gratefulness the timely help and invaluable advice given by my
colleagues in the WRL IIT Delhi during the process. I specially thank, Dr. Dinesh Kumar
Shukla, Dr. Kanwar Singh Arora, Dr. Rajneesh Kumar, Dr. A. S. Shahi, Dr. Kulwant Singh,
Dr. Manoj Kumar, Dr. Md. Zaheer Khan Yusufzai, and Mr. Ratnesh Kumar Raj for their
assistance and valuable discussions. I genuinely express my thanks to Mr. Dinesh Rathod who
devoted his valuable time to help me during experimental work and to enrich me with some
spectacular ideas. I also extend my heartfelt thanks to Dr. Arshad Noor Siddiquee for his good
wishes and help provided during writing of this thesis and last but not the least Md. Aadil
Ahmed of Jamia Milia Islamia Delhi, a summer trainee at WRL for his exhaustive help during
experimentation.
I would like to genuinely acknowledge the help rendered by Dr. Ashok Kumar Arora, the then
Director, YMCA Institute of Engineering (presently YMCA University of Science &
Technology, Faridabad and where I am working as Associate Professor) for allowing me to
enroll for Ph.D. at IIT Delhi. I register my deep sense of appreciation and thanks for the
invaluable support and timely help provided by Prof. Sandeep Grover (Chairman),
Department of Mechanical Engineering, YMCA University of Science & Technology,
Faridabad) and all my colleagues in the department specially Dr. Lakhwinder Singh, Dr.
Vikram Singh, Prof. Raj Kumar, Mr. Naresh Yadav, Dr. Sanjeev Goyal, Dr. Kamal Kumar
and Mr. Manmohan Kakkar.
I express gratitude to my dear parents for providing me the years of support and opportunity
to excel during my undergraduate and postgraduate studies that provided the foundation for
this work. Nothing I can say can do justice to how I feel about their way of upbringing
children. My father Sh. C.S. Verma, a veterinarian, always worked industriously to support
the family and spare no effort to provide the best possible environment for me to grow up and
attend school. He never complained in spite of all the hardships in his life. I have no
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appropriate word that can fully describe my mother Smt. Premwati, a perfect housewife, for
her endless love to me. She spent many sleepless nights accompanying me whenever I was
not well. I remember her constant support when I faced difficulties and I remember, most of
all, her delicious dishes. Mother and Father, I love you. The moral boost from my younger
sisters, Mrs. Pushpa Malik, M.Sc., M. Phil. and Ms. Vrantika Chaudhary, a post graduate in
Biotechnology was remarkable. I owe them everything and wish I could show them just how
much I love and appreciate them. I would like to dedicate this work to my lost Jijaji Dr.
Jitendra Malik, a charming and affectionate person who left us too soon. He was very much
caring and concerned about my research work and used to give tips for the same though it was
not his field. Although he is no longer with us, he is forever remembered. I am sure he shares
our joy and happiness in the heaven. I hope that this work makes him proud.
I also want to thank my parents in-law Sh. Veer Singh and Smt. Sunita for their unconditional
support and moral boost. I express sincere appreciation to my wife Sarita Chaudhary and feel
extremely fortunate for having her as life partner. Her encouragement, support, and unshaken
love were undoubtedly the substratum upon which the past twelve years of my life have been
built. Her quiet endurance and forbearance of my occasional bad moods is a proof in itself of
her uncompromising devotion. She always had faith in me and my intellect even when I felt
like digging hole and crawling into one because I didn‘t have faith in myself. I also thank my
little, cute and loving, daughters Nandini and Gauri for their love to me, although they often
had to endure my absence during this period.
Finally, I would like to thank everyone who had contributed directly or indirectly for this
research work and seek to be pardoned if I erroneously missed naming them here.
Hari Om
July, 2013
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ABSTRACT
Development is an ongoing process in any field. True is the case with welding processes and
technologies. Surfacing with the help of welding processes and their variants in their
conventional or modified mode has long been used in the past. While using welding processes
in surfacing and especially in cladding applications, control of dilution always remains the
engineers‘ concern in order to utilize the resources in an economical way and to achieve
improved life expectancy of the engineering components operating under the conditions of
corrosive atmosphere. Submerged arc welding process continues to be favourite for cladding
applications due to its high deposition capabilities despite its dilution apprehensions.
Considering the limitations of high dilution associated with submerged arc welding (SAW)
process, a new variant with some noticeable modifications was developed in the welding
research laboratory of IIT Delhi by Prof. Sunil Pandey with an objective to significantly
reduce the extent of dilution and named the process as advanced submerged arc welding
(ASAW) process. The modification helped to break the fixed dependency between the wire
feed rate, the resultant welding current and the electrode stickout. In the present work, this
new process has been explored by investigating the relationship between the process
parameters, welding current, welding voltage, weld bead geometry and shape relationships.
Dilution plays a vital role in metallurgy and economics of cladding, so keeping this in view,
process parameters have been optimized for optimum level of dilution so that the stainless
steel cladding process can be made cost effective. The work is distributed into different stages
so that the framed objective could be scientifically realized to best possible extent.
At the first stage, direct and indirect process parameters were selected and their ranges were
determined by running trial experiments by varying one factor at a time. During the trial runs
it was felt that the electrode polarity plays a decisive role in controlling the dilution. After
deciding the limits of parameters and considering electrode polarity as one among the other
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process variables, the experimentation was designed by using rotatable central composite
design (CCD) and accordingly a design matrix was formed. Experiments were performed
according to the design matrix and the responses corresponding to each run were recorded.
The correlations between the process parameters and important responses from the cladding
point of view were developed by using response surface methodology (RSM). Single and
multiple response optimization of the process parameters was then carried out using
desirability approach in order to achieve the optimum dilution.
Multipass multilayer cladded plates were prepared at the optimum dilution level conditions
for evaluating their quality in terms of mechanical and metallurgical performance such as
elements retention, ferrite content, microhardness and microstructures. Integrity of the
stainless steel clad layer on mild steel base was also checked by performing bend tests.
Major outcomes of the research work are as follows;
Potential of advanced submerged arc welding process is far better than convention
submerged arc welding process in ensuring the low dilution levels.
It was possible to quantify the main and interaction effects of process parameters on
the cladding responses and in turn the quality. Role of polarity was quite impressive in
improving the effectiveness of the new process.
ASAW process due to its low dilution capabilities can be used to clad thin plates
Hardness and ferrite content even in the first clad layer was found satisfactory thus
reducing the need for multilayer cladding.
Disbonding of stainless steel clad layers is of much concern that was found absent in
case of the ASAW process.
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TABLE OF CONTENTS
CERTIFICATE .................................................................................................... I
ACKNOWLEDGEMENTS ............................................................................. III
ABSTRACT ..................................................................................................... VII
TABLE OF CONTENTS .................................................................................. IX
LIST OF FIGURES ....................................................................................... XXI
LIST OF TABLES ................................................................................. XXXVII
NOMENTCLATURE USED ......................................................................... XLI
CHAPTER 1 ........................................................................................................1
INTRODUCTION ............................................................................................... 1
Introduction ...................................................................................................................... 1 1.1
Introduction to surface engineering / surfacing ............................................................... 2 1.2
1.2.1 Hardfacing ......................................................................................................... 3
1.2.2 Cladding ............................................................................................................ 3
1.2.3 Building up ........................................................................................................ 4
1.2.4 Buttering ........................................................................................................... 4
1.2.5 Electroplating .................................................................................................... 5
1.2.6 Other processes ................................................................................................. 5
Welding processes for cladding of materials ................................................................... 6 1.3
Introduction to advanced submerged arc weld-ing (ASAW) process .............................. 7 1.4
1.4.1 Process parameters in ASAW ........................................................................... 7
1.4.2 Advantages of ASAW ....................................................................................... 9
1.4.3 Limitations of ASAW ....................................................................................... 9
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1.4.4 Suitability of ASAW for cladding operations ................................................. 10
Objective of the current research work ........................................................................... 10 1.5
1.5.1 Issues covered in the research work ................................................................ 10
Research work plan ........................................................................................................ 11 1.6
Format of the thesis ........................................................................................................ 12 1.7
CHAPTER 2 ...................................................................................................... 17
LITERATURE REVIEW ................................................................................. 17
Introduction .................................................................................................................... 17 2.1
Cladding materials .......................................................................................................... 17 2.2
Cladding processes ......................................................................................................... 18 2.3
Submerged arc welding and cladding ............................................................................. 19 2.4
2.4.1 Chemical aspect of weldment .......................................................................... 20
2.4.2 Electrode wire melting rate, heat input and arc stability ................................. 22
2.4.3 Mechanical and metallurgical behaviour of weldment ................................... 24
2.4.4 Mathematical modeling and optimization in SAW ......................................... 26
2.4.4.1 Response surface methodology (RSM) and factorial design
for process modeling ........................................................................ 26
2.4.4.2 Artificial neural network (ANN) ...................................................... 28
2.4.4.3 Optimization techniques used in SAW ............................................ 30
Preheating of electrode wire ........................................................................................... 34 2.5
Advanced submerged arc welding .................................................................................. 36 2.6
Problems associated with dissimilar welding and cladding ........................................... 37 2.7
2.7.1 Fusion boundary transition region ................................................................... 42
2.7.2 Clad disbonding ............................................................................................... 43
2.7.3 Hydrogen induced cracking ............................................................................. 43
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2.7.4 Solidification cracking .................................................................................... 44
2.7.5 Creep failure in the HAZ of carbon steels ...................................................... 44
Corrosion ........................................................................................................................ 45 2.8
2.8.1 Economic aspect of corrosion in India ............................................................ 45
2.8.2 Types of corrosion .......................................................................................... 45
2.8.3 Corrosion of plane carbon steels ..................................................................... 46
Effect of alloying element .............................................................................................. 48 2.9
Weldability of mild steels .............................................................................................. 51 2.10
2.10.1 Solidification cracks ........................................................................................ 52
2.10.2 Hydrogen induced cracks ................................................................................ 53
2.10.3 Heat affected zone (HAZ) cracking ................................................................ 53
2.10.3.1 Lamellar tearing ................................................................................ 54
2.10.4 Microstructure development in mild steel welds ............................................ 54
Stainless steels ................................................................................................................ 56 2.11
2.11.1 Defects in fusion welded austenitic stainless steels and alloys ....................... 57
2.11.2 Solidification of austenitic stainless steel welds ............................................. 58
Ferrite content in stainless steel welds ........................................................................... 58 2.12
2.12.1 Prediction of ferrite content ............................................................................ 59
Summary ........................................................................................................................ 61 2.13
Identified gaps in the literature and proposed work ....................................................... 63 2.14
CHAPTER 3 ..................................................................................................... 73
DESIGN OF EXPERIMENTS......................................................................... 73
Introduction .................................................................................................................... 73 3.1
Terminology used in design of experiments .................................................................. 73 3.2
Basics principle of design .............................................................................................. 74 3.3
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3.3.1 Replication ....................................................................................................... 74
3.3.2 Randomization ................................................................................................. 74
3.3.3 Blocking .......................................................................................................... 74
Steps in experimentation ................................................................................................ 74 3.4
Need for statistically designed experiments ................................................................... 75 3.5
Different strategies used in the design of experiment .................................................... 75 3.6
3.6.1 One-factor experiments ................................................................................... 75
3.6.2 Several factors one at a time ............................................................................ 76
3.6.3 Several factors all at the same time ................................................................. 76
3.6.4 Full Factorial Design ....................................................................................... 77
3.6.5 Fraction Factorial design ................................................................................. 77
3.6.6 Taguchi Design ................................................................................................ 77
Response surface methodology ...................................................................................... 77 3.7
3.7.1 Designs for fitting response surfaces ............................................................... 81
3.7.2 Some common design properties..................................................................... 82
3.7.2.1 Orthogonality.................................................................................... 82
3.7.2.2 Rotatability ....................................................................................... 82
3.7.2.3 Uniform precision............................................................................. 83
3.7.2.4 Design robustness ............................................................................. 83
Central composite design (CCD) .................................................................................... 84 3.8
3.8.1 Determining the magnitude of star point ..................................................... 85
3.8.1.1 Circumscribed .................................................................................. 85
3.8.1.2 Inscribed ........................................................................................... 86
3.8.1.3 Face centred ...................................................................................... 86
Linear regression models ................................................................................................ 87 3.9
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3.9.1 Estimation of the coefficients in linear regression models ............................. 88
Analysis of variance ....................................................................................................... 93 3.10
Desirability function....................................................................................................... 93 3.11
Summary ........................................................................................................................ 96 3.12
CHAPTER 4 ................................................................................................... 101
EXPERIMENTATION ................................................................................... 101
Introduction .................................................................................................................. 101 4.1
Work material selection ............................................................................................... 101 4.2
4.2.1 Base material ................................................................................................. 101
4.2.2 Filler material ................................................................................................ 102
4.2.3 Granular Flux ................................................................................................ 102
Selection of equipment ................................................................................................. 104 4.3
4.3.1 Power source ................................................................................................. 104
4.3.2 Electrode wire feeding system ...................................................................... 105
4.3.3 Torch assembly ............................................................................................. 105
4.3.4 Flux distribution and recovery system .......................................................... 106
4.3.5 Travel equipment .......................................................................................... 106
4.3.6 Work table and positioners ........................................................................... 106
4.3.7 Auxiliary Power source ................................................................................. 107
Process parameters ....................................................................................................... 107 4.4
4.4.1 Machine based process parameters ............................................................... 107
4.4.1.1 Wire feed rate .................................................................................. 108
4.4.1.2 Open circuit voltage ........................................................................ 108
4.4.1.3 Travel speed .................................................................................... 109
4.4.1.4 Electrode polarity ............................................................................ 110
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4.4.1.5 Nozzle tip to plate distance (NTPD) .............................................. 110
4.4.1.6 Preheat current ................................................................................ 111
4.4.1.7 Electrode work angle ...................................................................... 111
4.4.2 Material based process parameters ................................................................ 112
4.4.2.1 Electrode size ................................................................................. 112
4.4.2.2 Electrode and base material ............................................................ 113
4.4.2.3 Base metal thickness ...................................................................... 114
4.4.2.4 Depth of flux .................................................................................. 114
4.4.2.5 Type and basicity index of flux ...................................................... 115
Selection of responses .................................................................................................. 116 4.5
4.5.1 Welding current ............................................................................................. 116
4.5.2 Welding voltage............................................................................................. 116
4.5.3 Weld bead geometry ...................................................................................... 117
4.5.3.1 Bead width ...................................................................................... 117
4.5.3.2 Reinforcement ................................................................................ 118
4.5.3.3 Penetration ...................................................................................... 118
4.5.3.4 WRFF and WPSF ........................................................................... 119
4.5.4 Dilution .......................................................................................................... 119
4.5.5 HAZ width ..................................................................................................... 120
4.5.6 Ferrite number ............................................................................................... 121
4.5.7 Vickers micro hardness ................................................................................. 121
Identification of important process parameters and selection of their range ................ 122 4.6
4.6.1 Categorical Variables .................................................................................... 123
4.6.2 Numeric Variables ......................................................................................... 123
Trial experimentation ................................................................................................... 124 4.7
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Conducting experimental runs for depositing mild steel bead using SAW ................. 125 4.8
Conducting experimetns for depositing ss bead on mild steel plates using asaw 4.9
process .......................................................................................................................... 127
4.9.1 Recording of responses ................................................................................. 129
Summary ...................................................................................................................... 129 4.10
CHAPTER 5 ................................................................................................... 143
TESTING AND ANALYSIS METHODS ..................................................... 143
Visual examination and DYE PENETRANT TEST .................................................... 143 5.1
Bead on plate test coupon ............................................................................................ 143 5.2
Mounting of Specimen ................................................................................................. 144 5.3
Bead profile .................................................................................................................. 144 5.4
Micro-hardness measurement ...................................................................................... 145 5.5
Ferrite Number measurement ....................................................................................... 146 5.6
Microstructural studies ................................................................................................. 147 5.7
5.7.1 Grinding and polishing of specimens ........................................................... 148
5.7.2 Metallographic etching ................................................................................. 149
Bend test ....................................................................................................................... 151 5.8
Chemical analysis......................................................................................................... 152 5.9
Summary ...................................................................................................................... 153 5.10
CHAPTER 6 ................................................................................................... 161
MODELING OF BEAD GEOMETRY ......................................................... 161
Introduction .................................................................................................................. 161 6.1
Observations during trial experiments ......................................................................... 161 6.2
6.2.1 Checking the adequacy of developed model................................................. 162
6.2.2 Significance of coefficients of the model ..................................................... 162
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Analysis of observed responses during trial runs ......................................................... 163 6.3
6.3.1 Effect of SAW parameter on bead width ...................................................... 163
6.3.2 Effect of SAW parameter on reinforcement .................................................. 164
6.3.3 Effect of SAW parameter on depth of penetration ........................................ 164
6.3.4 Effect of SAW parameter on HAZ width ...................................................... 165
6.3.5 Effect of SAW parameter on bead dilution ................................................... 166
Development of mathematical models for observed responses during stainless 6.4
steel bead on plate experiment ...................................................................................... 171
6.4.1 Testing of adequacy and significance of models ........................................... 171
6.4.2 Development of final models ........................................................................ 173
Analysis of models using response surface methodology ............................................ 173 6.5
6.5.1 Direct effects of process parameters on welding current (Iw) ....................... 174
6.5.1.1 Effect of wire feed rate (F) on welding current (Iw) ....................... 174
6.5.1.2 Effect of welding speed on welding current (Iw) ............................ 174
6.5.1.3 Effect of Open circuit voltage (VO) on welding current (Iw) .......... 175
6.5.1.4 Effect of preheating current (IP) on welding current (Iw) ............... 175
6.5.1.5 Effect of electrode polarity on welding current (Iw) ....................... 176
6.5.2 Interaction effects of process parameters on welding current (Iw) ................ 176
6.5.2.1 Interaction effect of travel speed (S) and preheating current
(IP) on current welding current (Iw) ................................................ 176
6.5.2.2 Effect of interactions between ASAW parameters and
electrode polarity on welding current (Iw) ...................................... 177
6.5.3 Direct effect of ASAW process parameters on welding voltage (Vw) .......... 177
6.5.4 Effect of electrode polarity on welding voltage (Vw) .................................... 179
6.5.5 Direct effect of ASAW process parameters on bead width (W) ................... 179
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6.5.6 Effect of electrode polarity on bead width (W) ............................................ 180
6.5.7 Direct effect of ASAW process parameters on reinforcement height
(H) ......................................................................................................... 181
6.5.8 Effect of electrode polarity on Reinforcement height (H) ............................ 182
6.5.9 Direct effect of ASAW process parameters on weld reinforcement
form factor (W/H) ......................................................................................... 182
6.5.10 Effect of electrode polarity on WRFF (W/H) ............................................... 183
6.5.11 Direct effect of ASAW process parameters on penetration (P) .................... 183
6.5.12 Effect of electrode polarity on penetration (P).............................................. 184
6.5.13 Interaction between ASAW process parameters and its effect on depth
of penetration (P) .......................................................................................... 184
6.5.14 Direct effect of ASAW process parameters on weld penetration shape
factor (W/P) .................................................................................................. 185
6.5.15 Effect of electrode polarity on WPSF (W/P) ................................................ 186
6.5.16 Direct effect of ASAW process parameters on dilution (%D)...................... 187
6.5.17 Effect of electrode polarity on dilution (%D) ............................................... 188
6.5.18 Direct effect of ASAW process parameters on heat affected zone width
(HAZ) ......................................................................................................... 189
6.5.19 Effect of electrode polarity on HAZ width ................................................... 189
6.5.20 Interaction effects of ASAW process parameters on HAZ width ................. 189
6.5.21 Direct effect of ASAW process parameters on ferrite number (FN) ............ 190
6.5.22 Effect of electrode polarity on ferrite number (FN) ...................................... 191
6.5.23 Interaction effects of ASAW process parameters on ferrite number
(FN) ......................................................................................................... 191
6.5.24 Direct effect of ASAW process parameters on bead hardness (HV100) ........ 192
xviii
6.5.25 Effect of electrode polarity on bead hardness (HV100) .................................. 193
Multiple response optimization using desira-bility function ........................................ 193 6.6
6.6.1 Analysis of single response optimization ...................................................... 194
6.6.1.1 Optimal conditions for minimum welding current ......................... 194
6.6.1.2 Optimal condition for a maximum welding current ....................... 195
6.6.1.3 Optimal condition for a target value of welding current ................ 195
6.6.1.4 Optimal condition for minimum dilution ....................................... 195
6.6.1.5 Optimal condition for minimum ferrite number............................. 196
6.6.1.6 Optimal condition for minimum bead hardness ............................. 196
6.6.2 Analysis of Multi response optimization ....................................................... 196
6.6.3 Confirmatory experiments ............................................................................. 197
Summary ....................................................................................................................... 198 6.7
CHAPTER 7 .................................................................................................... 247
MECHANICAL AND METALLURGICAL INVESTIGATIONS ON
SS WELD BEADS ........................................................................................... 247
Introduction .................................................................................................................. 247 7.1
Elemental retention in the Stainless steel bead on plate ............................................... 248 7.2
Study on stainless steel bead hardness ......................................................................... 250 7.3
Ferrite content in stainless steel weld beads ................................................................. 252 7.4
Metallographic studies .................................................................................................. 253 7.5
7.5.1 Metallographic studies in mild steel bead on mild steel plate ....................... 254
7.5.2 Metallographic studies for SS 308L bead on mild steel plate ....................... 257
Summary ....................................................................................................................... 260 7.6
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CHAPTER 8 ................................................................................................... 277
INVESTIGATIONS ON STAINLESS STEEL CLAD PLATES ............... 277
Introduction .................................................................................................................. 277 8.1
Study on elemental retention in clad layers ................................................................. 278 8.2
8.2.1 Nickel variation across clad layers................................................................ 278
8.2.2 Chromium variation across clad layers ......................................................... 279
8.2.3 Carbon variation across clad layers .............................................................. 279
8.2.4 Silicon variation across clad layers ............................................................... 280
8.2.5 Manganese variation across clad layers ........................................................ 280
Study on SS309L buttering layer ................................................................................. 281 8.3
8.3.1 Comparison of nickel content in layers ........................................................ 282
8.3.2 Comparison of chromium content in layers .................................................. 282
8.3.3 Comparison of carbon content in layers ....................................................... 283
8.3.4 Comparison of silicon content in layers ........................................................ 283
8.3.5 Comparison of manganese content in layers................................................. 284
Study of microhardness variation in clad layers .......................................................... 284 8.4
Study of ferrite variation in clad layers ........................................................................ 286 8.5
8.5.1 Confirmation of ferrite number (FN) by software prediction model ............ 287
Metallographic studies on SS cladding on mild steel plate using ASAW process ...... 289 8.6
Bend tests of cladded samples...................................................................................... 292 8.7
Summary ...................................................................................................................... 293 8.8
CHAPTER 9 ................................................................................................... 313
CONCLUSIONS AND SCOPE FOR FUTURE WORK ............................ 313
Conclusions .................................................................................................................. 313 9.1
9.1.1 Chapter 3 ....................................................................................................... 313
xx
9.1.2 Chapter 4 ....................................................................................................... 314
9.1.3 Chapter 5 ....................................................................................................... 315
9.1.4 Chapter 6 ....................................................................................................... 316
9.1.5 Chapter 7 ....................................................................................................... 321
9.1.6 Chapter 8 ....................................................................................................... 323
Scope for future work ................................................................................................... 326 9.2
BIBLIOGRAPHY ........................................................................................... 327
LIST OF PUBLICATIONS ............................................................................ 351
CURRICULUM VITAE ................................................................................. 353