Welding and Joining of Magnesium Alloys

Welding and Joining of Magnesium Alloys
Edited by
Liming Liu
Contents
Contributor contact details xi
Part I General 1
1 Introduction to the welding and joining of magnesium 3
L. Liu, Dalian University of Technology, China
1.1 Background 3
1.2 Characteristics of magnesium alloy welded joints
under dynamic load 4
1.3 Efficient gas metal arc welding of magnesium alloys 5
1.4 Dissimilar welding of magnesium alloys to other metals 6
1.5 References 7
2 Welding metallurgy of magnesium alloys 9
L. Liu, Dalian University of Technology, China
2.1 Introduction 9
2.2 Weldability of magnesium alloys 10
2.3 Weldability of magnesium alloys to other metals 12
2.4 References 14
3 Preparation for welding of magnesium alloys 16
L. Liu, Dalian University of Technology, China
3.1 Introduction 16
3.2 Surface treatment of magnesium alloys 16
3.3 Welding groove for magnesium alloys 18
3.4 Preheating and postweld treatments for magnesium alloys 20
3.5 References 22
vi Contents
4 Welding materials for magnesium alloys 23
L. Liu, Dalian University of Technology, China
4.1 Introduction 23
4.2 Hot extrusion process of welding materials 27
4.3 Component design of welding materials 32
4.4 Hot pull process of welding materials 34
4.5 Microstructure and strength of welding materials 35
4.6 References 36
5 Welding and joining of magnesium alloys to
aluminum alloys 38
L. Liu, Dalian University of Technology, China
5.1 Introduction 38
5.2 Hybrid laser-tungsten inert gas welding of magnesium
and aluminum 39
5.3 Diffusion bonding magnesium to aluminum technology 44
5.4 Laser weld bonding magnesium to aluminum technology 49
5.5 Conclusion and future trends 60
5.6 References 61
6 The joining of magnesium alloy to steel 63
L. Liu, Dalian University of Technology, China
6.1 Introduction 63
6.2 Existing problems in the joining of magnesium alloys to steel 64
6.3 Welding principles for the joining of magnesium alloys to steel 66
6.4 Direct joining of magnesium alloys to mild steel 69
6.5 Nickel-added joining of magnesium alloys to steel 74
6.6 Conclusion and future trends 77
6.7 References 77
7 Corrosion and protection of magnesium alloy welds 79
L. Liu, Dalian University of Technology, China
7.1 Introduction 79
7.2 Corrosion characteristics of magnesium alloy weldment 80
7.3 Improvement in the corrosion resistance of magnesium
alloy weldment 86
7.4 Conclusion and future trends 92
7.5 References 93Contents vii
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Part II Particular welding and joining techniques 95
8 Brazing and soldering of magnesium alloys 97
T. WaTanabe, Niigata University, Japan
8.1 Surface preparation of magnesium alloys before joining 97
8.2 Brazing of magnesium alloys using flux and filler metal 103
8.3 Ultrasonic brazing of magnesium alloys with no flux 112
8.4 Soldering of magnesium alloys 117
8.5 References 120
9 Mechanical joining of magnesium alloys 122
M. Heger, böllhoff, Germany and M. HorsTMann,
Hella KGaA Hueck & Co., Germany
9.1 Introduction 122
9.2 Technologies with pre-punching operation and one-sided
accessibility 123
9.3 Technologies with pre-punching operation and two-sided
accessibility 130
9.4 Technologies without pre-punching operation and one-sided
accessibility 133
9.5 Technologies without pre-punching operation and two-sided
accessibility 138
9.6 Linear technology: hemming 145
9.7 References 147
10 Adhesive bonding of magnesium alloys 149
L. Liu, Dalian University of Technology, China
10.1 Introduction 149
10.2 Surface treatments of magnesium alloys 149
10.3 Adhesive for the bonding of magnesium alloys 154
10.4 Cure for the bonding of magnesium alloys 154
10.5 Applications of the bonding of magnesium alloys 154
10.6 Future trends 158
10.7 References 158
11 Gas-tungsten arc welding of magnesium alloys 160
L. Liu, Dalian University of Technology, China
11.1 Introduction 160
11.2 Gas-tungsten arc welding of magnesium alloys
without filling wire 161
11.3 Gas-tungsten arc filler welding of magnesium alloys 168
11.4 References 1751 2 3 4 5 6 7 8 9
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viii Contents
12 Metal inert gas welding of magnesium alloys 178
g. song, Dalian University of Technology, China
12.1 Introduction 178
12.2 Pulsed metal inert gas welding for magnesium alloys 179
12.3 Alternating current metal inert gas welding for magnesium
alloys 185
12.4 Conclusion and future trends 194
12.5 References 194
13 Variable polarity plasma arc welding of magnesium alloys 197
Z.D. ZHang, Dalian University of Technology, China
13.1 Introduction 197
13.2 Variable polarity plasma arc welding of magnesium alloys 199
13.3 Variable polarity plasma arc weld bonding of magnesium
alloys 211
13.4 Conclusion and future trends 226
13.5 References 227
14 Hybrid laser-arc welding of magnesium alloys 229
g. song, Dalian University of Technology, China
14.1 Introduction 229
14.2 Low-power laser/arc hybrid welding of magnesium 230
14.3 Hybrid welding process with filler metal 244
14.4 Practical application 250
14.5 Conclusion and future trends 251
14.6 References 251
15 Activating flux tungsten inert gas welding of
magnesium alloys 253
Z.D. ZHang, Dalian University of Technology, China
15.1 Introduction 253
15.2 Welding mechanism 254
15.3 Welding parameters 258
15.4 Microstructure of welding joints 267
15.5 Mechanical properties 271
15.6 Future trends 272
15.7 References 272
16 Friction stir welding of magnesium alloys 274
H. ZHang, University of Science and Technology, Beijing, China
16.1 Introduction 274
16.2 Welding parameters and procedures 276
16.3 Welding tools and equipment 2801 2 3 4 5 6 7 8 9
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Contents ix
16.4 Materials that have been or are being friction stir welded 282
16.5 Typical microstructures of friction stir welded magnesium
alloys 282
16.6 Properties of friction stir welded magnesium alloys 289
16.7 Weld defects of friction stir welded magnesium alloys 295
16.8 Applications of friction stir welded magnesium alloys 300
16.9 Future trends and sources of further information and advice 301
16.10 Acknowledgements 301
16.11 References 301
17 Laser welding of magnesium alloys 306
J. sHan, Tsinghua University, China
17.1 Introduction 306
17.2 Character of the laser welding process and influence
of laser welding parameters 307
17.3 Laser welding of magnesium alloys 318
17.4 Microstructure and properties of laser welding of magnesium
alloys 322
17.5 Typical defects of laser welding of magnesium alloys 332
17.6 Outlook and future trends 346
17.7 References 347
18 Resistance spot welding of magnesium alloys 351
L. Liu, University of Waterloo, Canada, J. Feng, Harbin Institute
of Technology, China and Y. ZHou, University of Waterloo, Canada
18.1 Introduction 351
18.2 Fundamentals of resistance spot welding 351
18.3 Welding conditions: surface 354
18.4 Welding conditions: welding parameters 358
18.5 Nugget growth and microstructure 359
18.6 Welding of magnesium alloys to other alloys 362
18.7 Equipment for the welding of magnesium alloys 363
18.8 Future trends 364
18.9 References 365
19 Electromagnetic pulse welding of magnesium to
aluminium sheets 367
s. Kore, Indian Institute of Technology, Guwahati, India and J. iMberT,
Y. ZHou and M. WorsWicK, University of Waterloo, Canada
19.1 Introduction 367
19.2 Fundamental theory of electromagnetic welding 368
19.3 Equipment for electromagnetic welding 369
19.4 Welding technique and materials 372
19.5 Mechanical and metallurgical testing of welds 374x Contents
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19.6 Safety guidelines while handling the electromagnetic
welding setup 377
19.7 References 378
Index 380380
abrasion methods, 150
ACEN see alternating current electrode
negative
ACEP see alternating current electrode
positive
acetone, 150
activating flux tungsten inert gas welding,
253–72
base metal and melted materials oxygen
contents, 271
effect of activating fluxes
surface appearance, 266
weld morphology, 266
future trends, 272
joints microstructure, 267–71
crystal grain size, 268
EDS analysis, 269
fusion zone XRD analysis, 270
secondary electron images, 269
mechanical properties, 271–2
room temperature tensile test
results, 271
weld penetration
activating flux coating density, 264
argon shielding gas flowrate, 262
penetration depth vs arc length with
different activating fluxes, 261
welding current effect, 259
welding speed, 263
with vs without activating flux, 265
welding mechanism, 254–8
arc image of Mg alloy with oxide fluxes
on one side, 256
effects of fluxes on weld shape, 257, 258
flux application on one side of the
joint, 257
mechanisms affecting the penetration
characteristics, 257
Mg alloy with and without oxide fluxes
arc image, 255
specimen used in TIG/ATIG welding
trials, 254
welding configuration, 255
welding parameters, 258–67, 265
arc length, 260
flux thickness, 263–7
Mg alloy welds produced with and
without activating flux, 259
shielding gas flowrate, 261–2
welding current, 259–60
welding speed, 262
adhesive bonding
applications, 154, 157–8
adhesive layer containing SiO2, 158
automotive magnesium parts, 157
magnesium alloy door inner panel, 157
specimens with SiO2 particles, 157
future trends, 158
magnesium alloys, 149–58
adhesives characteristics, 155–6
adhesives used, 154
cure for the bonding, 154
surface treatments, 149–53
group pre-treatment/coating/adhesive
combinations, 152
Lap-shear peak stress before and after
corrosion testing, 152
Lap-shear samples before and after
corrosion testing, 153
pre-treatment and powder coating
process, 150
aerodynamic forces, 256
airborne grit blasting, 150
AlF
3 flux, 260
alkaline detergent solution, 150
alternating current electrode negative, 199
alternating current electrode positive, 200
alternating current MIG welding, 185–94
aluminium, 7
aluminium alloys
welding and joining with magnesium
alloys, 38–61
diffusion bonding, 44–9
future trends, 60–1
hybrid laser-tungsten inert gas
welding, 39–44
laser weld bonding, 49–60
aluminium coating, 91
aluminium rivets, 131
Ampere’s law, 367
antimony, 6
arc spraying
post-treatment technology, 87–91
Al-rich epoxy resin based paint on
aluminium coating, 88
arc-sprayed Al and MAO coating
IndexIndex 381
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polarisation curves, 92
coating morphologies, 90
corrosion kinetics of epoxy resin and
paint sealed coatings, 89
epoxy resin sealed coating and Al-rich
paint, 88
epoxy resin sealing treatment, 87–9
hydrothermal sealing technology, 89–90
MAO coating surface images, 92
micro-arc oxidation treatment, 90–1
SSIT coatings corrosion kinetics, 91
technology, 86–7
arc welding, 320
argon, 160, 316
argon gas, 261
ASTM D 1384, 293
ASTM D 2651, 150, 151
AZ31
arc-sprayed aluminium coating on welded
joint, 86
cross-sectioned weld joint images, 83
longitudinal section morphologies of lap
joints, 87
low-power laser-TIG hybrid welded alloy to
mild steel polarisation curves, 85
AZ31B, 178, 180, 186, 211
EPMA patterns after hybrid overlaps
welding, Plate V
AZ91
corrosion potential and corrosion current
density, 81
different zones microstructure, 82
laser-arc hybrid welded joint cross-section
macrostructure, 80
laser-TIG hybrid welded alloy polarisation
curves, 81
magnification microstructure, 82
bar coil, 370
bimetallic corrosion, 292
blind riveting, 124–7
additional terms of connection, 125
blind rivet with closed rivet body, 126
body folding blind rivet made of
aluminium, 126
nuts/thread bolts, 126–7
blind rivet nuts with a closed body, 127
setting process, 127
process steps, 125
unprocessed body folding blind rivet, 124
BMW 5 series, 129
bolt, 132
brazing, 97–117
compositions and melting temperatures
commercial brazing filler metals, 107
low-temperature brazing filler
metals, 107
compositions, hardness, liquidus and
brazing temperature
In-Mg-Zn system filler metals, 108
Mg-Sn-In-Al system filler metals, 111
microstructures of brazed layer performed
with applying time
0.5 to 4.0 seconds, 116
2.0 to 8.0 seconds, 115
6.0 seconds, 114
ultrasonic brazing with no flux, 112–17
apparatus, 113
applying time and tensile strength, 115
AZ31B polished surface before and after
heating, 117
bonding process, 116–17
fracture path in joint brazed, 114
joining temperatures and tensile
strength, 113
processes schematic, 117
ultrasonic vibration temperature and
applying time effect on brazing, 112–15
using flux and filler metal, 103–12
brazeable magnesium alloys compositions
and melting temperatures, 106
CaCl
2-LiCl-KCl equilibrium phase
diagrams, 105
filler metal development, 105–12
flux development, 103–5
fluxes compositions, 105
joint broken at base metal after crosstensile test, 109
joint broken at base metal and fillet
appearance, 112
magnesium brazing fluxes compositions
and operational temperatures, 104
Mg-In system equilibrium phase diagram,
108
spread area for fluxes, 106
brazing temperature, 112, 114
buoyancy forces, 256
calcium, 103
carbon dioxide, 318
castings, 20, 21
CdCl
2 flux, 261
cerium, 40, 43–4, 48, 60
chemical methods, 149
chromating pre-treatments, 151
chrome conversion coatings, 151
classical hemming process, 146
clinching, 142–5
alloy AZ31 characteristic joining elements,
145
joining element characteristics, 144–5
process steps using a split die, 143
CO
2 laser welding, 311
coarse grains, 11
coefficient of thermal expansion, 65
cold cracks, 13
cold forming screws, 137
columnar dendritic zone, 362
columnar-to-equiaxed transition, 361
compression coil, 370
contact reaction brazing, 38–9
conventional riveting, 130–1
magnesium connection using aluminium solid
rivet, 131
process steps using solid rivet, 131
conversion coatings, 151
corrosion, 13–14
cutting clinch processes, 143
DC pulsed MIG welding, 186
deep penetration welding, 310–11
degreasing methods, 150
depth-to-width ratio (DWR), 72
diffusion bonding, 44–5382 Index
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magnesium to aluminium, 44–9
interfacial microstructure, 45
joint microstructure, 45–8
mechanical properties, 48–9
Mg-Al joint with zinc bond region analysis
results, 47
Mg-Al joints with zinc alloy interlayer, 46
welding mechanism, 49
direct joining techniques, 69–74
direct screwing
with pre-punching and one-sided
accessibility, 128–9
thread-forming self-tapping screw
application, 130
thread-forming self-tapping screw
processing, 129
without pre-punching and one-sided
accessibility, 134–7
cold-forming screws, 137
flow drill screws, 135–7
process steps of cold forming screw, 137
dissimilar metal welding, 38
drop shot transfer, 191
electrode negative, 186
electrode positive, 186
electromagnetic forces, 256
electromagnetic induction, 144
electromagnetic property, 65–6
electromagnetic welding, 367–77
equipments, 369–72
capacitor, 371
coil types, 370
field shapers, 371–2
high-voltage power supply, 371
high-voltage switch, 371
work coil, 369–70
fundamental theory, 367–9
mechanical and metallurgical testing,
374–5
Mg to Al welds shear-tested
samples, 374
opened weld interface and cross-section
XRD spectra, 376
shear strength with variation in discharge
energy, 374
wavy interface and complete metal
continuity, 375
principle, 368
safety guidelines, 377
welding technique and materials, 372–3
current waveform, 373
Mg to Al sheet weld, 373
welding set-up, 372
electromotive force, 368
electron beam welding, 321
electron probe microanalysis, 213, 214, 237,
Plate I, Plate IV, Plate V
EPMA see electron probe microanalysis
epoxy adhesive, 211, 222
epoxy resin sealing treatment, 87–9
equiaxed dendritic zone, 362
ER AZ101A filler metal, 23
ER AZ61A filler metal, 23
ER AZ92A filler metal, 23
ER EZ33A filler metal, 23
European End-of-Life Vehicle Directive, 151
evaporation, 10–11, 13
expansion coil, 370
expulsion, 356
filler metals, 23, 244
development for brazing magnesium
alloys, 105–12
In-Mg-Zn system, 107–10
brazed joints strength, 108
compositions, hardness, liquidus and
brazing temperature, 108
joint crossed section brazed with
In-4Zn, 110
Mg-Sn-In-Al system, 110–12
compositions, hardness, liquidus and
brazing temperature, 111
strength of brazed joints, 111
recommended for arc welding, 24
filler wire, 169
welding, 16
flanging, 140
process steps, 141
typical joints, 141
flat pancake type coil, 370
flow drill screws, 135–7
functional sections and process steps, 136
joining process
with pre-punching, 136
without pre-punching, 137
focal position, 313
mode transition curve
determined by laser power and focal
position, 317
determined by welding speed and focal
position, 318
relationship with spot size and power
density, 317
sketch, 315
friction stir welding, 4, 7, 38, 274–301, 321
advantages, 275
applications, 300
future trends, 301
joint configurations, 276
parameters and procedures, 276–80
effect of welding speed on pore area in stir
zone, 279
friction stir welds at different welding
pressures, 280
temperature distributions, 277
tilt angle, 279
ultimate strength and welding
parameters, 278
welding and rotation speed, 276–9
welding pressure, 280
salt spray tested-FSW AZ31 Mg sample
macrograph, 293
micrograph, 294
sample materials, 282
schematic drawing, 275
tools and equipment, 280–2
selection of tools designed at TWI, 281
weld defects, 295–300
defects at different welding speeds, 297
FSW AZ31 Mg typical defects, 296
micro-pore fill procedure, 298
micro-pore produced during welding, 298
void formation, 300Index 383
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welded alloy microstructures, 282–8
advancing and retreating side
microstructures, 287
friction stir welded AZ31 alloy
macrograph, 282
heat-affected zone, 285–6
mechanism of microstructure
evolution, 288
microstructure evolution on weld
nugget, 289
nugget zone, 283–5
onion rings in the weld nugget, 283
thermo-mechanically affected
zone, 285
weld nugget microstructure, 284
zone microstructures along TMAZ line,
weld nugget and crown, 286
welded alloys properties, 289–95
corrosion properties, 291–4
crack cross-section, 291
fatigue properties, 291
Hall–Petch type relationship, 295
other mechanical properties, 294–5
tensile fracture location, 290
tensile properties, 289–91
typical fracture modes, 292
fusion stir welding, 61
fusion zone, 79, 81, 82, 181
galvanic corrosion, 152, 292
gas metal arc welding, 23, 197
gas-tungsten arc filler welding, 160–75
hardness testing, 175
mechanical properties, 172–5
principle, 161
tensile properties, 172–4
geometry size and location, 174
specimens fractography, 174
specimens properties, 174
welded joint
grain size contrast, 173
GTAF and GTA appearance
contrast, 171
hardness analysis, 175
macro-morphology, 171
microstructure, 171–2
transition zone, 172
welding parameters, 169–71
effect on weld shape, 170–1
normative interval, 169
wire feed rate effect, 170
gas-tungsten arc welding, 23, 160–75, 197
see also gas-tungsten arc filler welding;
gas-tungsten arc welding without
filling wire
GTAF and GTA-welded joints appearance
contrast, 171
welded joint microstructure, 173
gas-tungsten arc welding without filling
wire, 161–8
hardness testing, 167–8
hardness distribution, 168
weld joints average hardness, 167
mechanical properties, 165–8
preparing for welding, 161–2
tensile properties, 165–7
AZ31B size and position, 165
heat input and strength relationship, 166
specimens properties, 165
tensile fractures, 167
welded joint
AZ31B microstructure observation and
results, 163
heat input, HAZ and grain size
relation, 164
macrograph, 162
macrophotograph under heat input
conditions, 162
microstructure observation and
analysis, 163–5
microstructures, 164
GMAW see gas metal arc welding
grain bit vector, 288
GTAW see gas-tungsten arc welding
Hall–Petch relationship, 295
HAZ see heat-affected zone
heat capacity, 65
heat stress, 11–12
heat-affected zone, 79, 81, 82
friction stir welding, 285–6
gas-tungsten arc welding, 160
laser-arc hybrid welding, 231
metal inert gas welding, 181
resistance spot welding, 354, 360
variable polarity plasma arc
welding, 205
helium, 316
hemming, 145–7
magnesium sheet roller hemming, 147
process steps, 146
hot chromic acid, 151
hot cracks, 11, 179, 332
hot extrusion process, 27–32
extrusion device, 30
extrusion steps, 30
fluxing agent composition, 27
magnesium alloy ingot
after machining, 29
extrusion, 29–30
preparation, 27–9
process flowchart, 31
processing parameter, 31–2
hot pull process, 34–5
hot pull equipment diagram, 34
process parameters, 34–5
hybrid lap welding process, 43
hybrid laser-tungsten inert gas welding, 4, 66,
67, 69–70
magnesium and aluminium, 39–44
Ce added joint major elements EPMA
image and distribution maps,
Plate I
configuration, 40
direct joint fractography, 44
fusion zone microstructure and
composition, 42
joint interface, 43
joint with cerium fractography, 44
lap joint microstructures, 41
strength of samples with different cerium
foil thickness, 40
weld pool bottom microstructures, 42
hydrogen, 11, 339–40384 Index
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intermetallic compound layer (IMC),
68–9, 77
iron, 84
joining see specific joining technique
Joule’s law, 352
Kapton sheet, 372
keyhole, 309
Langrangian–Eulerian formulation, 299
lanthanum, 6
lap joining method, 66
laser bond welding, 7
laser power, 312
and heat input on welding mode, 312
effect on welding seam depth and width, 313
mode transition curve determined by laser
power and focal position, 317
laser weld bonding, 49–50
magnesium to aluminium, 49–60
binary equilibrium phase diagram, 53
different zones in joint, 58
elements distribution in fusion zone, 54–6
fracture location with favourable and
imperfect infusion, 60
joint microstructure, 50–60
joint transverse section, 55
joints tensile shear strength, 59
laser welding and LWB joint images and
quantitative analysis, 56
magnesium fusion zone microstructure, 52
mechanical properties, 56
Mg-Al interface in fusion zone
microstructure, 54
Mg-Mg17Al12 microstructure, 52
quantitative analysis, 57
transverse section of joints, 51
welding mechanism, 59–60
laser welding, 306–47
absorption of metals
as function of laser radiation
wavelength, 308
as function of temperature, 308
AM50 without heating and after heating, 342
focal position, 313–14
depth and mode, 316
relationship with spot size and power
density, 317
sketch of, 315
influence of parameter combination on weld
shape parameter, 316
magnesium alloys, 318–19
advantages in welding, 320–2
physical properties of Mg, Al, Fe, 319
weldability, 319–20
microstructure and properties, 322–31
base metal and welds mechanical
properties, 329
components in selected area in the
fracture, 331
different zones in depth direction of
weld, 326
different zones in width direction of
weld, 325
laser welds microstructure, 323–7
microhardness distribution, 328–9
weld centre microstructure, 323
weld components, 324
weld fracture shapes, 330
weld XRD analysis, 324
white impurities components, 331
ZE41A-T5 sand casting Mg alloy
microstructure, 327
mode transition curve
determined by laser power and focal
position, 317
determined by welding speed and focal
position, 318
outlook, 346–7
porosity, 336–45
change before and after remelting, 345
die-cast Mg alloys initial pores final
diameters, 340
large pores formation, 339
pores characteristic parameters in AM50
base metal, 340
pores in laser welding seam, 338
relationship with welding speed, 344
single-side welding vs double-side
welding, 346
under different power, 343
under different speed (Jiguo Shan’s
research), 343
under different speed (Marya’s
research), 343
pressure and temperature changes during hot
vacuum pumping, 341
process character, 307–11
heat input and laser power on welding
mode, 312
influence of plasma, 311
laser multiple reflection on keyhole
surface, 310
physical process, 307–11
various processes in different power
density laser radiations, 309
typical defects, 332–45
magnesium alloys welding problems, 332
molten pool collapse, 334–6
shielding gas optimised flow, 335
weld surface formation, 337
welded ZE41A-T5 alloy joint liquation
cracking, 333
welding crack, 332–4
welding parameters, 311–18
complex influence of several
factors, 314–15
laser beam character, 311–12
laser power, 312
shielding gas, 315–16, 318
welding speed, 313
welding seam depth and width
laser power, 313
welding speed, 314
welds mechanical properties, 327–31
microhardness, 327–9
tensile strength, 329–31
laser-arc hybrid welding, 321
application, 250
autocycle products, 250
bicycle products, 250
AZ31B EPMA patterns after hybrid overlaps
welding, Plate VIndex 385
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future trends, 251
hybrid welding process with filler
metal, 244–50
distance between laser and arc influence on
weld formation, 247
filler wire feeding modes, 245
fracture scanned photograph, 249
hybrid welding modes appearances, 245
joint with back-feeding filler wire
microstructure, 249
tensile strength, 248–50
weld joints vs back-feeding filler wire, 246
weld microstructure, 248
welding defects, 247–8
welding defects under unsuitable
parameters, 248
welding mode, 245–6
welding parameters, 246–7
low-power laser/arc hybrid welding, 230–44
AZ31 to AZ91 joint microstructure, 237
AZ31 weld hardness profile, 239
AZ31, AZ61 and AZ91 alloys
microstructure, 236
AZ31B weld joint macrographs, 241
AZ61 to AZ31weld hardness profile, 240
AZ61weld hardness profile, 240
AZ91 to AZ31weld hardness profile, 241
AZ91weld hardness profile, 240
defocusing value effect, 233
dissimilar welds cross-sections, 232
distance between laser and arc effect on
weld seam formation, 235
fatigue test results, 239
hybrid welding joint microstructure, 235
joints appearance of A131 to AZ31 and
AZ31 to AZ91, 231
mechanical properties, 237–41
microstructure, 235–7
optimal hybrid welding parameters, 234
pore element distribution, 242
pore formation sketch map, 243
pores in weld metal using laser coaxial
shielding, 243
pores in weld metal using laser lateral
shielding, 244
porosity, 241–4
tensile test results, 238
TIG welded joint microstructure, 236
weld depths variation, 232
weld metal, 237
welded joints macro-sections and
appearances, 231
welded seam morphology, 231
welding speed effect on weld seam, 234
magnesium alloys, 229–51
hybrid laser-tungsten inert gas
welding, 230
welding parameters influence, 232–4
arc power, 232
defocusing value, 233
distance between laser and arc, 234
welding speed, 233
laser-tungsten inert gas welding, 40, 231
see also hybrid laser-tungsten inert gas
welding
liquation cracking, 333–4
lithium, 103
local thermodynamic equilibrium, 225
lock-ring bolts, 132–3
processing steps, 133
Lorentz forces, 256, 368, 371–2
LWB see laser weld bonding
magnesia, 10
magnesium, 3, 242
physical and chemical properties of
magnesium and steel, 65–6
physical properties, 10
welding and joining techniques, 3–7
alloys to other metals dissimilar
welding, 6–7
efficient gas metal arc welding, 5–6
welded joints characteristics under
dynamic load, 4–5
magnesium alloy welds
corrosion and protection, 79–93
corrosion characteristics, 80–4
corrosion current densities and corrosion
potentials, 84
laser-arc hybrid welded AZ91 magnesium
sheet behaviour, 80–3
magnesium alloy to dissimilar metals
joints, 83–4
soldered joint between magnesium and
aluminium, 85
weld joint corrosion macrostructures, 84
corrosion resistance improvement, 86–91
arc spray technology, 86–7
post-treatment technology of arc
spraying, 87–91
magnesium alloys, 3, 79
activating flux tungsten inert gas
welding, 253–72
future trends, 272
mechanical properties, 271–2
welding joints microstructure, 267–71
welding mechanism, 254–8
welding parameters, 258–67
adhesive bonding, 149–58
adhesives used, 154
applications, 154
characteristics, 155–6
cure for the bonding, 154
future trends, 158
surface treatments, 149–53
brazing and soldering, 97–120
brazing using flux and filler metal, 103–12
soldering, 117–20
ultrasonic brazing with no flux, 112–17
classification, 322
dissimilar welding to other metals, 6–7
efficient gas metal arc welding, 5–6
electromagnetic welding, 367–77
equipments, 369–72
fundamental theory, 367–9
mechanical and metallurgical
testing, 374–5
safety guidelines, 377
welding technique and materials, 372–3
friction stir welding, 274–301
applications, 300
future trends, 301
materials that have been or are being
friction stir welded, 282386 Index
1 2 3 4 5 6 7 8 9
10
1 2 3 4 5 6 7 8 9
20
1 2 3 4 5 6 7 8 9
30
1 2 3 4 5 6 7 8 9
40
1 2
43X
parameters and procedures, 276–80
tools and equipment, 280–2
typical microstructures, 282–8
weld defects, 295–300
welded alloys properties, 289–95
gas-tungsten arc welding, 160–75
principle, 161
with filler wire, 168–75
without filler wire, 161–8
laser welding, 306–47
alloys weldability, 318–22
microstructure and properties, 322–31
outlook, 346–7
process character and influence of welding
parameters, 307–18
typical defects, 332–45
laser-arc hybrid welding, 229–51
application, 250
future trends, 251
hybrid welding process with filler metal,
244–50
low-power laser/arc hybrid
welding, 230–44
mechanical joining techniques, 122–47
hemming, 145–7
with pre-punching and one-sided
accessibility, 123–9
with pre-punching and two-sided
accessibility, 130–3
without pre-punching and one-sided
accessibility, 133–7
without pre-punching and two-sided
accessibility, 138–45
metal inert gas welding, 178–94
alternating current MIG welding, 185–94
future trends, 194
pulsed MIG welding, 179–85
preheating and postweld treatments, 20–2
castings, 21
preparation for welding, 16–22
resistance spot welding, 351–65
electrode tip profiles after 40 welds,
Plate III
equipment, 363–4
fundamentals, 351–4
future trends, 364–5
magnesium alloy welding to other
alloys, 362–3
nugget growth and microstructure,
359–62
surface welding conditions, 354–8
welding parameters, 358–9
slip systems, 32
steel joining techniques, 63–77
direct joining, 69–74
existing problems, 64–6
future trends, 77
Mg, Ni and Fe element distribution maps,
Plate II
nickel-added joining, 74–7
welding principle, 66–9
surface preparation before joining, 97–103
aluminium and magnesium alloys
joinability, 98
brazing filler metal solidified on
surfaces, 102
Mg2p photoelectron XPS spectra, 99
microphotographs around ultrasonically
welded interfaces, 102
surface film on magnesium, 97–8
surface film on magnesium and
aluminium, 98
surface film thickness and components, 100
surface treatment on ultrasonic welds
strength, 101
surface treatment to improve joinability,
98–103
weld fracture surface, 101
surface treatment, 16–18
chemical pre-treatment methods, 17
pre-treatment methods for wire, 18
welding defects, 17
wires and weld, 18
variable polarity plasma arc weld bonding,
211–26
variable polarity plasma arc welding,
199–211
process, 198
welding and joining with aluminium alloys,
38–61
diffusion bonding, 44–9
future trends, 60–1
hybrid laser-tungsten inert gas
welding, 39–44
laser weld bonding, 49–60
welding groove, 18–20
types for repairing welding, 20
types for welding, 19
welding materials, 23–36
component design, 32–3
hot extrusion process, 27–32
hot pull process, 34–5
microstructure and strength, 35–6
welding metallurgy, 9–14
other metals, 12–14
relative weldabilities with common
grades, 12
weldability, 10–12
welding problems, 332
magnesium chloride, 27
magnesium oxide, 11
manganese coating conversion, 151
MAO see micro-arc oxidation
Marangoni effect, 256, 265, 270
mechanical joining techniques, 122–47
hemming, 145–7
magnesium sheet roller hemming, 147
roller hemming and bonding
procedure, 146
pre-punching and one-sided
accessibility, 123–9
blind rivet nuts/thread bolts, 126–7
blind riveting, 124–6
direct screwing, 128–9
functional element Rivkle Elastic, 127–8
pre-punching and two-sided
accessibility, 130–3
conventional riveting, 130–1
lock-ring bolts, 132–3
screw nut joint, 132
punctual joining techniques
classification, 123
without pre-punching and one-sided
accessibility, 133–7Index 387
1 2 3 4 5 6 7 8 9
10
1 2 3 4 5 6 7 8 9
20
1 2 3 4 5 6 7 8 9
30
1 2 3 4 5 6 7 8 9
40
1 2
43X
direct screwing, 134–7
tac setting, 133–4
without pre-punching and two-sided
accessibility, 138–45
clinching, 142–5
flanging, 140
self-piercing riveting with semi-tubular
rivet, 138–40
self-piercing riveting with solid
rivet, 141–2
melting point, 64–5
metal inert gas welding, 178–94
alternating current MIG welding, 185–94
arc and weld appearance, 190
arc morphological change, 187
base metal and weld beads
microstructure, 193
butt and lap joint appearances, 191
butt joints weld appearance, 192
designed current waveform, 186
metal transfer arc, 188
parameters plates with different
thickness, 191
parameters range for metal transfers, 190
weld beads appearance, 189
weld beads macrostructures, 193
wire speed parameters, 192
future trends, 194
pulsed MIG welding, 179–85
base metal and weld beads
microstructures, 183
drop detachment, 184
force on the drop from the detached
wire, 185
pulse frequency effect on joint
formation, 182
spatters and hot cracking, 180
weld appearances, 182
weld beads microstructures, 184
weld width and pulse rework current, 180
welding speed effect on joint
formation, 181
metal inner gas welding, 5
Mg(OH)2 coating, 151
micro-arc oxidation treatment, 90–1
MIG see metal inert gas welding
momentum theory, 299
nickel-added joining techniques, 74–7
nitric acid cleaning, 356
nitrogen, 316, 318
non-chrome conversion coatings, 151
non-cutting round clinch processes, 143
nugget
friction stir welding, 283–5
resistance spot welding, 359–62
oxidation, 10–11, 13
oxide films, 292
oxidisability, 66
PAW see plasma arc welding
Pilling–Bedworth ratio, 97
plasma arc welding, 197
polypropylene sheet, 154
pores, 11
porosity, 241–4, 336–45
porosity ratio, 343
pulse current, 185
pulse tungsten inert gas welding, 11
pulsed MIG welding, 179–85
pulsed rework current, 180, 187
recrystallised, 283
resistance spot welding, 351–65
electrode tip profiles after 40 welds, Plate III
equipment, 363–4
fundamentals, 351–4
dynamic resistance, 353
general principles, 351–3
involved resistances, 352
weld nugget microstructure, 353–4
future trends, 364–5
magnesium alloy welding to other
alloys, 362–3
Mg/steel spot weld cross-section, 363
nugget growth and microstructure, 359–62
AZ31-SA with micro-scale Al
8Mn5, 361
AZ31-SB with micro- and nano-scale
Al
8Mn5, 361
surface welding conditions, 354–8
contact resistance of different surface
conditions, 355
electrode tip faces surface profiles,
Plate III
fracture surface, 357
weld strength vs nugget size, 356
welding parameters, 358–9
process window, 360
Rivkle Elastic
functional element, 127–8
connection, 128
unprocessed and processed state, 128
roll-hemming process, 146
rolling deformation, 166
screw nut joint, 132
screws see specific screw
self-locking, 132
self-piercing riveting
semi-tubular rivet, 138–40
AZ31 monotype joint, 140
joining process with increasing setting
speed, 140
joint set at room temperature, 139
terms and process steps, 138
solid rivet, 141–2
joining element characteristic, 143
process steps, 142
shear strength tests, 46, 48
skin depth, 369
soldering, 117–20
AZ31/AZ31 joint interfaces, 119
new solders compositions and melting
temperatures, 119
soldered joints tensile strength, 119
solders for magnesium, 118
solenoid coils, 370
solidification cracking, 332
solubility, 66
spot spacing, 359
steel joining techniques, 63–77
direct joining, 69–74
defocus on joint strength, 70–2388 Index
1 2 3 4 5 6 7 8 9
10
1 2 3 4 5 6 7 8 9
20
1 2 3 4 5 6 7 8 9
30
1 2 3 4 5 6 7 8 9
40
1 2
43X
defocusing amount on weld bead strength
and width, 71
direct joint microstructures, 73
laser power on joint strength, 69–70
laser power on weld bead strength, 70
mechanical properties, 74
microstructure characteristics, 73–4
sample in tensile shear test, 74
tungsten inert gas current on joint
strength, 72–3
welding current on weld bead strength, 72
welding speed on joint strength, 70
welding speed on top weld width and weld
bead strength, 71
existing problems, 64–6
future trends, 77
Mg, Ni and Fe element distribution maps,
Plate II
nickel-added joining, 74–7
interface between magnesium alloy and
nickel interface, 76
joint with nickel interlayer
microstructure, 75
microstructure characteristics, 74–6
microstructure SEM images, 75
nickel distribution, 76
shear test results, 77
welded joint properties, 76–7
welding procedure, 74
physical and chemical properties of
magnesium and steel, 65–6
welding principle, 66–9
direct joining principle, 67–8
interfacial microstructure, 68
joint cross-section, 68
Mg-Ni-Fe joint, 69
principle of interlayer into lap joint, 68–9
test specimens, 67
welding method, 66–7
superplastic deformation, 288
surface tension, 267
surface treatment
magnesium alloys to improve joinability,
98–103
surface film thickness and components, 100
surface treatment and ultrasonic
weldability, 100–2
surface treatment and wettability in
brazing, 102–3
x-ray photoelectron spectroscopy analysis
on treated surface, 99
tabletop hemming, 146
tac setting, 133–4
connection and process steps, 134
joining element characteristic, 135
target depth, 280
thermal conductivity, 9, 65
thermal spray technology, 93
thermo-mechanically affected zone, 279, 285
thread-forming self-tapping screws, 128–9
TIG see tungsten inert gas
tin coating conversion, 151
TiO
2 flux, 260, 261
transition layer, 68–9
trichloroethylene, 150
tungsten inert gas, 230
tungsten inert gas current, 72–3
tungsten-arc inert gas welding, 160
vacuum diffusion bonding, 39
see also diffusion bonding
variable polarity plasma arc weld bonding
arc behaviour observation, 224–6
ACEN stage ionisation atmosphere, 225
argon and CO2 physical properties, 226
VP-PAW and VP-PAWB process, 224
keyhole mode process investigation, 211–13
weld bead surfaces, 212
magnesium alloys, 211–26
elements distribution measurement, 222–3
transverse section EPMA analyses,
Plate IV
mechanical property measure, 223–4
tensile shearing test results, 223
pores behaviour investigation, 213–19
cross-section with different flow rates of
plasma gas, 215
EPMA analysis, 214
joint cross-section, 213
joint porosity, 213–14
molten width change with different
welding currents, 216
molten width change with different
welding speeds, 217
plasma gas flow rate, 214–15
pores total area and heat input
relationship, 218
remedy for eliminating pores, 217–19
welding current, 215–16
welding joint cross-section by optimal
welding parameters, 219
welding parameters effect, 214
welding speed, 216–17
welding joint morphology and microstructure,
219–22
VP-PAW vs VP-PAWB transverse
section, 221
weld pool shape, 221
welding seam morphology, 220
variable polarity plasma arc welding,
197–227
alternating current electrode negative time to
cycle ratio, 199–202
magnesium alloy butt welding, 200
tungsten melting loss comparison, 201
variable polarity current waveform, 199
welding joints failure loads, 201
catelectrode clean effect on welding joint
mechanical property, 204–6
variations effect on joint dimension and
strength, 205
magnesium alloy with lap joint, 206–11
alloy weld pool shape, 210
AZ31B weld microstructure, 210
hardness distribution in joint, 209
magnesium alloy welding
appearance, 206
schematic diagram, 207
tensile test results, 207
test specimens, 208
welding characters, 206–7
welding joints mechanical
properties, 207–8Index 389
1 2 3 4 5 6 7 8 9
10
1 2 3 4 5 6 7 8 9
20
1 2 3 4 5 6 7 8 9
30
1 2 3 4 5 6 7 8 9
40
1 2
43X
welding joints microstructure, 209–11
magnesium alloys, 199–211
AZ31 alloy plasma arc welding
appearance, 199
process, 198
welding parameters effect on welding
process, 202–4
nozzle structure, 203
processing parameter on AZ31B
alloy, 202
welding currents and speeds effect on
welding width, 203–4
VP-PAW see variable polarity plasma arc
welding
VP-PAWB see variable polarity plasma arc
weld bonding
waterborne grit blasting, 150
weight loss method, 33
welding
see also specific type of welding
magnesium alloys preparation, 16–22
preheating and postweld treatments, 20–2
surface treatment, 16–18
welding groove, 18–20
magnesium alloys to aluminium alloys, 38–61
diffusion bonding, 44–9
future trends, 60–1
hybrid laser-tungsten inert gas welding,
39–44
laser weld bonding, 49–60
main problem, 39
welding defects, 10–12, 17
welding groove, 18–20
welding materials
component design, 32–3
boiling point of Mg-Zn with different
composition, 33
hot extrusion process, 27–32
extruding process flowchart, 31
extrusion device, 30
extrusion steps, 30
fluxing agent composition, 27
magnesium alloy ingot after
machining, 29
magnesium alloy ingot extrusion, 29–30
magnesium alloy ingot preparation, 27–9
processing parameter, 31–2
hot pull process, 34–5
hot pull equipment diagram, 34
process parameters, 34–5
magnesium alloys, 23–36
filler metals for arc welding, 24
melting flow process chart, 29
slip systems, 32
welding wire composition, 24
welding wire selection, 26
microstructure and strength, 35–6
magnesium alloy welding wire
microstructure, 35
welding wire ultimate tensile strength and
elongation, 35
welding metallurgy
magnesium alloys, 9–14
magnesium, aluminium and iron physical
properties, 10
relative weldabilities with common
grades, 12
weldability, 10–12
weldability to other metals, 12–14
welding wire
composition, 24
microstructure, 35
selection, 26
ultimate tensile strength and elongation, 36
Whorl and MX-Triflute, 281
zinc, 45, 49, 60
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