DEVELOPMENT OF IRON BASED HARDFACING CONSUMABLES FOR SURFACING
by
MANOJ KUMAR
Department of Mechanical Engineering
Submitted
in fulfillment of the requirements of the degree of DOCTOR OF PHILOSOPHY
to the
INDIAN INSTITUTE OF TECHNOLOGY DELHI
SEPTEMBER, 2010
This research work is dedicated to
Orphans, hunger, helpless and hopeless people of Earth
CERTIFICATE
This is to certify that the thesis entitled "Development of iron based hardfacing consumables for surfacing" being submitted to the Indian Institute of Technology Delhi, by Mr. Manoj Kumar is worthy of consideration for the award of the degree of Doctor of Philosophy and is a record of the original bonafide 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
Department of Mechanical Engineering Indian Institute of Technology Delhi Hauz Khas, New Delhi-110 016, India.
Dr. S. Aravindan Department of Mechanical Engineering Indian Institute of Technology, Delhi Hauz Khas, New Delhi-110 016, India.
1
ACKNOWLEDGMENT
I would like to express my sincere thanks and gratitude to the research supervisors Prof.
Sunil Pandey, Professor, Department of Mechanical Engineering, Indian Institute of Technology Delhi and Dr. S. Aravindan, Assistant Professor, Department of Mechanical Engineering, Indian Institute of Technology Delhi for their tireless efforts and valuable suggestions throughout the research.
I would like to thank all citizens of Indian Republic, who made this wonderful Institute where I did my research work.
I would like to thank the team of experts and the members of the Students Research Committee (SRC), for this research work at the Indian Institute of Technology Delhi which includes Prof. P. V. M. Rao, Professor, Department of Mechanical Engineering, Dr. D. Ravi Kumar, Associate Professor, Department of Mechanical Engineering and Prof. D. K. Sahgal, Professor,Department of Applied Mechanics, for all the support, encouragement and their valuable suggestions.
I would like to thank Late Mr. Mahinder Singh, Mr. A. Siva Kumar, Sr. Technician, Mr.
Ayodhya Prasad, Junior Lab Technician, Mr. Duli Chand Meena and Mr. Sunil Kumar, Welding laboratory for their wholehearted cooperation and conscientious effort to overcome various hurdles met during the experimental work.
I gracefully acknowledge with gratitude that the timely help given by my colleagues in the welding group during the process. I would like to thank, especially to Dr. Sachin Mashewari, Dr. Narendra Mohan Sun, Dr. S. Thiruchitrambalam, Dr. Reeta Wattal, Dr.
Pankaj Mistry, Dr. Kulwant Singh, Dr. Kanwar Singh Arora, Dr. Rajneesh Kumar, Mr.
Dinesh Kumar Shukla, Mr. Hari Om Chaudhary, Md. Zaheer Khan Yusafzai, Md. Saied Irfan, Mr. Nikesh Parson, Mr. Abhisekh Pandey, Mr. Anchal Sondhi, Mr. Anand Dev and Mr. Varun Mittal for their assistance and valuable discussions.
During my stay for the research work, I would wish to acknowledge the support of my hostel mates specially Mr. G. H. V. C. Chary, Mr. Dinesh Kumar Shukla, Md. Ziauddin,
Mr. Alok Dixit, Mr. A. Ramesh, Mr. Ajit Patnaik, Mr. Ganesh W. Rathod, Mr. Naveen Padki, Mr. Sanjeev Srivastava along with others whose names are not mentioned here.
I would like to thank my heartfelt Guru Prof. Sunil Pandey, who developed my vision towards life, which is much more important than education, my Guru Mata Mrs. Anita Pandey, my cute sister Ms. Srishti and brother Mr. Kshitij Pandey for their love and caring nature, which never made me to miss my family.
I express my deep gratitude to my parents Shri. Mewa Ram and Smt. Munni Devi to given me the immense freedom to think and execute, what I dreamed. I would like to thanks my family members for their effort to aid and assist me at every moment of my life. The support, love and encouragement got from them finds no words to express. The supports from my younger siblings, Mr. Mukesh Kumar, a Bank Professional with SBI, Mr. Manish Kumar, A. E. in UPPWD, Ms. Vijay Laxmi and Ms. Archana was remarkable.
Finally, I would like to thank everyone who had contributed directly or indirectly for this research work and I seek to be pardoned, if I erroneously missed naming them here.
(Manoj Kumar) September 2010
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ABSTRACT
Surfacing is an important tool in Tribology to reduce the wear and tear of engineering components. In surfacing a layer of wear resistant material deposited over the base metal or a substrate to improve the surface characteristics. There are numerous processes and consumables available in the market to improve the surface characteristics of components but each and every welding process has its own consumables. No single consumable is available that can be utilized by every arc welding process.
In the present research work iron based hardfacing consumables were developed. Work is divided into two systems. In the first system, chromium carbide hard facing electrodes were developed. Development of chromium carbide hardfacing electrode was carried out in two stages. Initially E7016 flux formulation was developed to evaluate the effect of various fluxing minerals on element transfer of alloying elements. Then ferrochrome, graphite, calcium based minerals and rutile were used for the formulation of hardfacing electrode. Potassium silicate was used as a binder. Coating ratio was 2. Extruded electrodes were air dried for 24 hours. Further it was backed at 400C for 2 hours. L9 Taguchi orthogonal array was used to optimize the Hardfacing flux. Chemical pads were made for spectro analysis test and micro hardness tests were also carried out. Micro structural analysis with color metallography was carried out to reveal the chromium carbide formation.
Extruded electrodes had excellent weld operating characteristics. Weld operating characteristics include the arc initiation, arc stability, arc re-initiation, spatter formation, fume formation, noise, slag detachability and low current requirements for operation.
Element transfer behaviors were studied with different layers of hardfaced material on substrate. Excellent hardness was achieved.
In the second system, a paste of ferrochrome, graphite and basic oxide with potassium silicate binder were used. L9 Taguchi orthogonal array was used to optimize the paste flux. Paste was uniformly coated on mild steel with the coating thickness of 1.5, 2 and 2.5 mm. A custom-made die was designed to ensure the uniform coating thickness of paste on substrate. Coated plate was preheated at 75°C for half hour and further 125°C for half hour. After that weld bead was deposited with SMAW, SAW, GMAW and GTAW process. Single layer of composite material was used for spectro analysis test and hardness test. Microstructural analysis with color metallography was carried out to reveal the chromium carbide formation. It was found that the paste coating gives the excellent results in single layer due to the breaking of arc force in between the two electrodes.
Paste was in between the two electrodes breaks the arc earlier than substrate. It facilitates the lower dilution and excellent alloying element transfer to the weldmetal.
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TABLE OF CONTENTS
Certificate i
Acknowledgements iii
Abstract v
Table of Contents vii
List of Figures xvii
List of Tables xxiii
Nomenclature xxix
TABLE OF CONTENTS
CHAPTER -1: INTRODUCTION 1-27
1.0 Surfacing 1
1.1 Surfacing Materials 3
1.1.1 Iron based alloys 4
1.1.2 Nickel based alloys 6
1.1.3 Cobalt based alloys 7
1.2 Welding Processes used for Hardfacing 7
1.2.1 Oxyacetylene welding 8
1.2.2 Powder welding 8
1.2.3 Manual metal arc welding 9
1.2.4 Gas-metal-arc welding 9
1.2.5 Flux cored arc welding 10
1.2.6 Gas Tungsten Arc welding process 11
1.2.7 Advanced Gas Metal Arc Welding (AGMAW) Process 11
1.2.8 Submerged arc welding 14
1.2.9 Advanced Submerged arc welding 14
1.2.10 Plasma spraying 15
1.2.11 Spray-fusing 16
1.2.12 Metalizing 16
1.3 SMAW Fluxes 17
1.3.2 Characteristics of basic fluxes 18
1.3.3 Flux Properties 18
1.3.3.1 Particle / grain size 19
1.3.3.2 Electrical / Electrolytic conductivity 19
1.3.3.3 Slag detachability 19
Arc stability 19
Surface tension 19
Viscosity 20
1.3.4 Basicity Index 20
1.3.5 Elements 21
Transfer
1.3.5.1 Silicon transfer 21
1.3.5.2 Manganese transfer 22
1.3.5.3 Carbon transfer 22
1.3.5.4 Sulphur and Phosphorus transfer 22
1.3.5.5 Chromium transfer 22
1.4 Motivation for Research 23
1.5 Technology Developed for Research Work 24
1.6 Importance and Application of Research Work 25
1.7 Research Work Plan 25
CHAPTER — 2: DESIGN OF EXPERIMENTS 29-55
2.0 Introduction 29
2.1 Design of Experiments 31
2.1.1 Choice of Experimental Designs 33
2.1.1.1 Factorial designs 33
2.1.1.2 Central composite design 34
2.1.1.3 Response surface methodology 35
2.2 Evolution of Experimental Approach 35
2.2.1 Theoretical approach 36
2.2.2 Qualitative approach 36
2.2.3 Qualitative-cum-Dimensional Analysis approach 38
2.2.4 Specific quantitative approach 38
2.2.5 General quantitative approach 39
2.3 Principles of Experimental Designs 40
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2.3.1 Replication 40
2.3.2 Randomization 40
2.3.3 Control 41
2.4 Modeling and Optimization Techniques 41
2.4.1 Artificial Neural Systems 42
2.4.2 Tolerance Box Method 43
2.4.3 Genetic Algorithm (GA) 43
2.4.4 Finite Element Modelling 44
2.4.5 Taguchi Method 44
2.4.5.1 Selection of Orthogonal Array (OA) 45
2.5 Analysis of Means 46
2.5.1 Level totals and Average 47
2.5.2 Main effects due to parameters 47
2.6 Analysis of Variance 47
2.7 Signals-to-Noise Ratio (S/N Ratio) 50
2.7.1 Conversion of results into S/N ratios 51
2.8 Empirical Model of Process 52
2.9 DOE for present research work 53
CHAPTER — 3: FLUXES 57-94
3.1 Introduction 57
3.1.1 Function of Fluxes 57
3.2 Coatings and fluxes in the welding of steel 58
3.2.1 Composition of Coatings 58
3.2.2 Metallurgy of Coatings 64
3.2.3 Slag 66
3.2.4 Inclusions in Core Wire 68
3.2.5 Inclusions in Base Metal 70
3.2.6 Arc Stabilizers 71
3.2.7 Arc Atmosphere 73
3.2.8 Viscosity 73
3.2.9 Surface Tension 74
3.3 Effect of various alloying and impurity elements on weldability of steels 75
3.3.1 Effect of Interstitial Elements 76
3.3.1.2 Sulphur 77
3.3.1.3 Phosphorus 78
3.3.1.4 Nitrogen 78
3.3.1.5 Hydrogen 79
3.3.1.6 Oxygen 80
3.3.1.7 Boron 81
3.3.2 Effect of Substitutional Elements 82
3.3.2.1 Manganese 82
3.3.2.2 Silicon 83
3.3.2.3 Nickel 84
3.3.2.4 Chromium 84
3.3.2.5 Molybdenum 85
3.3.2.6 Copper 86
3.3.2.7 Zirconium 86
3.3.2.8 Vanadium 85
3.3.2.9 Titanium 88
3.3.2.10 Aluminium 88
3.3.2.11 Tungsten 89
3.3.2.12 Cobalt 89
3.3.2.13 Rare Earth Elements 90
3.3.2.14 Niobium 90
3.3.2.15 Uranium 92
3.4 Base Material 92
3.5 Flux Formulation for 7016 Electrode 93
3.6 Flux Formulation for C-Cr Hardfacing Electrodes 93 3.7 Flux Formulation for C-Cr Paste Coating Technique 94
CHAPTER — 4: RESULTS AND DISCUSSION ON 95-
HARDFACING ELECTRODES 151
4.1 Formulation of 7016 Flux and its Average Responses 95
4.1.1 Chemical composition of weld metal 95
4.1.2 Operating characteristics of extruded E7016 electrodes 96 4.1.3 Effect of various process parameters on element transfer 98
behavior
4.1.3.1 Effect of parameters on Carbon recovery 98 x
4.1.3.2 Effect of parameters on Manganese 99 recovery
4.1.3.3 Effect of parameters on Silicon recovery 101 4.1.3.4 Effect of parameters on Sulfur transfer 102 4.1.3.5 Effect of parameters on Phosphorous 104
transfer
4.1.4 Mathematical model 105
4.1.5 Validation of model 105
4.2 Hardfacing Electrode 106
4.2.1 Operating characteristics of Hardfacing electrodes 107
4.3 First Layer of Hardfaced Deposit 108
4.3.1 Parameter range of minerals and its responses 108 4.3.2 Effect of various process parameters on element transfer 109
behavior
4.3.2.1 Effect of parameters on Carbon recovery 109 4.3.2.2 Effect of parameters on Manganese 111
recovery
4.3.2.3 Effect of parameters on Silicon recovery 112 4.3.2.4 Effect of parameters on Sulfur transfer 113 4.3.2.5 Effect of parameters on Phosphorous 115
transfer
4.3.2.6 Effect of parameters on Chromium 116 recovery
4.3.2.7 Effect of parameters on Hardness 118
4.3.3 Mathematical Model 119
4.4 Second Layer of Hardfaced Deposit 119
4.4.1 Parameter range of minerals and its responses 119 4.4.2 Effect of various process parameters on element transfer 120
behavior
4.4.2.1 Effect of parameters on Carbon recovery 120 4.4.2.2 Effect of parameters on Manganese 121
recovery
4.4.2.3 Effect of parameters on Silicon recovery 123 4.4.2.4 Effect of parameters on Chromium 124
4.4.2.5 Effect of parameters on Sulfur Transfer 125 4.4.2.6 Effect of parameters on Phosphorous 127
Transfer
4.4.2.7 Effect of parameters on Hardness of weld 128 metal
4.4.3 Mathematical Model 129
4.5 Third Layer of Hardfaced Deposit 130
4.5.1 Parameter range of minerals and its responses 130 4.5.2 Effect of various process parameters on element transfer 130
behavior
4.5.2.1 Effect of parameters on Carbon recovery 130 4.5.2.2 Effect of parameters on Chromium 132
Transfer
4.5.2.3 Effect of parameters on Manganese 133 Transfer
4.5.2.4 Effect of parameters on Silicon Transfer 134 4.5.2.5 Effect of parameters on Sulfur Transfer 135 4.5.2.6 Effect of parameters on Phosphorous 137
Transfer
4.5.2.7 Effect of parameters on Hardness of weld 138 metal
4.5.3 Mathematical Model 139
4.6 Fifth Layer of Hardfaced Deposit 140
4.6.1 Parameter range of minerals and its responses 140 4.6.2 Effect of various process parameters on element transfer 140
behavior
4.6.2.1 Effect of parameters on Carbon recovery 140 4.6.2.2 Effect of parameters on Chromium 142
Transfer
4.6.2.3 Effect of parameters on Manganese 143 Transfer
4.6.2.4 Effect of parameters on Silicon Transfer 144 4.6.2.5 Effect of parameters on Sulfur Transfer 146 4.6.2.6 Effect of parameters on Phosphorous 147
Transfer
xu
4.6.2.7 Effect of parameters on Hardness of weld 148 metal
4.6.3 Mathematical Model 150
4.6.4 Validation of Model 150
4.7 Comparison of different alloying element transfer with different layer of 150 weld metal
CHAPTER — 5: PASTE TECHNIQUE 153-
210
5.1 Introduction 153
5.2 Ferrochrome and Graphite Paste with 6013SS SMAW Electrode 155
5.2.1 Welding condition 155
5.2.2 Results and discussion 155
5.2.2.1 Effect of parameters on Carbon recovery 156 5.2.2.2 Effect of parameters on Chromium 157
recovery
5.2.2.3 Effect of parameters on Silicon recovery 158 5.2.2.4 Effect of parameters on Manganese 160
recovery
5.2.2.5 Effect of parameters on Sulfur transfer 161 5.2.2.6 Effect of parameters on Phosphorous 162
transfer
5.2.2.7 Effect of parameters on Hardness of weld 164 metal with 6013SS SMAW electrode
5.2.3 Mathematical Model for paste coating technique using 6013SS 165 SMAW electrode
5.2.4 Validation of Model 166
5.3 Ferrochrome and Graphite paste with 7018 SMAW Electrode 166
5.3.1 Welding condition 166
5.3.2 Results and discussion 166
5.3.2.1 Effect of parameters on Carbon recovery 167 5.3.2.2 Effect of parameters on Chromium 168
recovery
5.3.2.3 Effect of parameters on Silicon recovery 169
recovery
5.3.2.5 Effect of parameters on Sulfur transfer 172 5.3.2.6 Effect of parameters on Phosphorous 173
transfer
5.3.2.7 Effect of parameters on Hardness 175
5.3.3 Mathematical Model 176
5.3.4 Validation of Model 176
5.4 Ferrochrome and Graphite paste with SAW process 177
5.4.1 Welding condition 177
5.4.2 Results and discussion 177
5.4.2.1 Effect of parameters on Carbon recovery 179 5.4.2.2 Effect of parameters on Chromium 179
recovery
5.4.2.3 Effect of parameters on Silicon recovery 180 5.4.2.4 Effect of parameters on Manganese 181
recovery
5.4.2.5 Effect of parameters on Sulfur transfer 183 5.4.2.6 Effect of parameters on Phosphorous 184
transfer
5.4.2.7 Effect of parameters on Hardness 186
5.4.3 Mathematical Model 187
5.4.4 Validation of Model 188
5.5 Ferrochrome and Graphite Paste with GMAW process 188
5.5.1 Welding condition 188
5.5.2 Result and discussion 188
5.5.2.1 Effect of parameters on Carbon recovery 189 5.5.2.2 Effect of parameters on Chromium 190
recovery
5.5.2.3 Effect of parameters on Manganese 191 recovery
5.5.2.4 Effect of parameters on Silicon recovery 193 5.5.2.5 Effect of parameters on Sulfur transfer 194 5.5.2.6 Effect of parameters on Phosphorous 195
transfer
5.5.2.7 Effect of parameters on Hardness 196 xiv
5.5.3 Mathematical Model 198
5.5.4 Validation of model 198
5.6 Ferrochrome and Graphite paste with GTAW process 199
5.6.1 Welding condition 199
5.6.2 Result and discussion 199
5.6.2.1 Effect of parameters on Carbon transfer 199 5.6.2.2 Effect of parameters on Chromium transfer 201 5.6.2.3 Effect of parameters on Silicon transfer 202 5.6.2.4 Effect of parameters on Manganese transfer 203 5.6.2.5 Effect of parameters on Sulfur transfer 205 5.6.2.6 Effect of parameters on Phosphorous 206
transfer
5.6.2.7 Effect of parameters on Hardness 207
5.6.3 Mathematical Model 208
5.6.4 Validation of Model 209
5.7 Comparison of different alloying element recovery with different welding 209 processes
CHAPTER 6: METALLURGICAL INVESTIGATION 211- 248
6.1 Introduction 211
6.2 Color Metallography 215
6.3 Reagents Based on Complex Thiosulfate Solution 216
6.4 Complex Thiosulfate Reagents 217
6.5 Sample preparation 217
6.5.1 Sectioning 217
6.5.2 Mounting 217
6.5.3 Polishing 218
6.5.4 Etching 218
6.6 Microstructural observation 220
6.6.1 Microstructure of weld metal deposited with Hardfacing 220 Electrodes
6.6.2.1 Microstructure of weld metal deposited 227 with E6013 electrode on paste coating
with E7018 electrode on paste coating
6.6.2.3 Microstructure of weld metal deposited 236 with submerged arc welding process on
paste coating
6.6.2.4 Microstructure of weld metal deposited 238 with gas metal arc welding process on paste
coating
6.6.2.5 Microstructure of weld metal deposited 242 with gas tungsten arc welding process on
paste coating
6.7 Micro Hardness observation 246
6.7.1 Micro Hardness survey of weld deposit made with hardfacing 246 electrode
6.7.2 Micro Hardness survey of weld deposit made with paste 247 coating technique
CHAPTER 7:CONCLUSION 249-
257
7.1 E7016 flux formulation 249
7.2 Chromium Carbide Hardfacing electrodes 250
7.2.1 First layer of Chromium Carbide Hardfacing electrode weld 250 metal deposit
7.2.2 Second layer of Chromium Carbide Hardfacing electrode weld 251 metal deposit
7.2.3 Third layer of Chromium Carbide Hardfacing electrodes weld 252 metal deposit
7.2.4 Fifth layer of Chromium Carbide Hardfacing electrodes weld 253 metal deposit
7.2.5 Microstructure 254
7.2.6 Microhardness 255
7.3 Paste Coating Technique 255
7.3.1 Paste Coating Technique with 6013SS,7018 SMAW Electrode 255 7.3.2 Paste Coating Technique with SAW Process 256 7.3.3 Paste Coating Technique with GMAW Process 256 7.3.4 Paste Coating Technique with GTAW Process 257
7.3.5 Microstructure 257
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