age hardening see precipitation hardening
alloy elements 35–36
alloying interstitial and substitutional 14
alloy metallurgy 40–46
heat treatable 43–46
non-heat treatable 40–43
aluminium
applications 7
characteristics 4, Appendix B
history 1
backing bars and strips 78–80
butt welds definitions 75–78
cold work (strain hardening) 15–16
defects 199–205
hot cracking 24–31
oxide filming 22–24
porosity 18–22
‘suck-back’ in TIG welding 111
degreasing 66–68
mechanical cleaning 66
chemical cleaning (pickling) 67
design
backing bars and strips 78–80
edge preparations (joint design) 72–78
edge preparations (joint design) for MIG
136–139
edge preparations (joint design) for TIG
98–99
effect of position 72
for access 70–71
designations 36–40
alloy composition identification 36–38
temper designations 38–40
distortion 84–89
electron beam welding
capabilities 157, 160
process principles 155–157
fatigue 89–96
joint classification 92–94
filler metals effect on hot cracking 29–31 selection 46–50
fillet weld definitions 74, 75 friction welding
friction stir welding 161–165 capabilities 163, 164, 165 mechanical properties 165 process principles 160–161 rotary motion 161 gamma radiography 213
GMAW see MIG
grain size 12–13 effect on hot cracking 30
GTAW see TIG
handling of parent metals 51 laser cutting 58–63
health and safety 60–63 parameters 61 principles 58–60 laser welding arc augmented 154–155
CO2 laser welding 152–153 defects 154
Nd-YAG (solid state) welding 153–154 process principles 150–152
liquation cracking see hot cracking
mechanical cutting 64–66 MIG welding
arc starting 135 contact tip 129–130 electro-gas welding 143–144 filler wire 133–134
fine wire 124 mechanised and robotic welding 141–143 parameters (argon shielding) 136–137 parameters (helium shielding) 138 power sources 119–121
process principles 116–118
Index
235
Trang 2pulsed MIG 121–124
shielding gases 130–133
spot welding 144–146
terminating the weld 140–141
torches 125–126
torch positioning 138–140
twin wire 124–125
wire feeders 127–128
non-destructive testing 205–215
eddy current 207–208
penetrant 205–207
radiography 211–215
ultrasonic 208–211
penetrant examination 205–207
plasma arc cutting 52–58
health and safety 56–58
parameters 55
principles 52–54
plasma arc welding
parameters 149
plasma MIG 150
process principles 147–149
variable polarity 149
porosity 18–22
in autogenous welds 18
in parent metal 22
effect of cleanliness 21
composition 20
hose type 20
process 20
gas dew point 20
ISO classification 200
precipitation (age) hardening 16–17
resistance welding
flash butt welding 176–180
power sources 167–169
seam welding 175–176
spot welding 171–175
surface condition 169–171
solidification cracking see hot cracking solid solution strengthening see alloying
storage of parent metals 52 strengthening mechanisms 10–18 strength loss 31–34
in HAZ 32–34
in weld metal 31–32 TIG welding
effects of HF 100 mechanised/ automated welding 114– 115
parameters (argon shielding) 104 parameters (helium shielding) 113 process principles 97–101 shielding gas 102–106 spot and plug welding 115 torches and cables 106–107 torch manipulation 110–112 tungsten electrodes 108–109 ultrasonic examination 208–211 water jet cutting 63–64 weldability 18–31 hot cracking 24–31 oxide film 22–24 porosity 18–22 welder approval ASME IX 193, 196, 197
BS EN 287 Pt 2 191–193
BS EN 1418 197–198 welding procedure 181–182, 183 welding procedure approval ASME IX 188–190
BS EN 288 Pt 4 182–188 alloy grouping 184 range of approval 187–188 test regime 185–187 x-radiography 213