Advanced Welding Processes: Technologies and Process Control

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An introduction to welding processes 5 metallic bonds form across the interface and a cold pressure weld is formed. [4] The main characteristics of cold pressure welding are: ∑ the simplicity and low cost of the equipment; ∑ the avoidance of thermal damage to the material; ∑ it is most suitable for low-strength (soft) materials. The pressure and deformation may be applied by rolling, indentation, butt welding, drawing or shear welding techniques. In general, the more ductile materials are more easily welded. This process has been used for electrical connections between smalldiameter copper and aluminium conductors using butt and indentation techniques. Roll bonding is used to produce bimetallic sheets such as Cu/Al for cooking utensils, Al/Zn for printing plates and precious-metal contact springs for electrical applications. Friction welding {42} In friction welding, a high temperature is developed at the joint by the relative motion of the contact surfaces. When the surfaces are softened, a forging pressure is applied and the relative motion is stopped (Fig. 1.3). Material is extruded from the joint to form an upset. The process may be divided into several operating modes in terms of the means of supplying the energy: (1) Continuous drive: in which the relative motion is generated by direct coupling to the energy source. The drive maintains a constant speed during the heating phase. (2) Stored energy: in which the relative motion is supplied by a flywheel which is disconnected from the drive during the heating phase. Rotational motion is the most commonly used, mainly for round components where angular alignment of the two parts is not critical (Fig. 1.4). If it is required to achieve a fixed relationship between the mating parts, angular oscillation may be used and for non-circular components the linear and orbital techniques may be employed. Features of the process include: ∑ one-shot process for butt welding sections; ∑ suitable for dissimilar metals; ∑ short cycle time; ∑ most suited to circular sections; ∑ robust and costly equipment may be required. The process is commonly applied to circular sections, particularly in steel, but it may also be applied to dissimilar metal joints such as aluminium to steel or even ceramic materials to metals. Early applications of the process
6 Advanced welding processes Stage 1 A B Stage 2 A B Stage 3 Stage 4 A B A B 1.3 Friction welding. Stage 1: A fixed, B rotated and moved into contact with A. Stage 2: A fixed, B rotated under pressure, interface heating. Stage 3: A fixed, forge pressure applied. Stage 4: relative motion stopped, weld formed. (a) (b) (c) 1.4 Friction welding variants: (a) normal rotational motion, (b) linear oscillation, (c) angular oscillation. included the welding of automotive stub axles, but the process has also been applied to the fabrication of high-quality aero-engine parts, [5] duplex stainless steel pipe for offshore applications [6] and nuclear components. [7] Recent developments of the process include the joining of metal to ceramics, [8] the use of the process for stud welding in normal ambient conditions and underwater, and the use of the process for surfacing. [9] The linear technique
Page 2 and 3: Advanced welding processes i
Page 4 and 5: Advanced welding processes Technolo
Page 6 and 7: Contents Preface ix Acknowledgement
Page 8 and 9: Contents vii 10.4 Automated control
Page 10 and 11: Welding has traditionally been rega
Page 12 and 13: Acknowledgements I would like to ac
Page 14 and 15: 1.1 Introduction Welding and joinin
Page 16 and 17: An introduction to welding processe
Page 22 and 23: Stage 1 Stage 2 An introduction to
Page 24 and 25: Slag deposit on weld surface An int
Page 26 and 27: ∑ no heavy slag - reduced post-we
Page 30 and 31: Electro slag SAW multi wire SAW FCA
Page 32 and 33: Weld metal used (kg m -1 ) 40 35 30
Page 34 and 35: Advanced process development trends
Page 36 and 37: % consumed 70 60 50 40 30 20 10 Adv
Page 38 and 39: Advanced process development trends
Page 40 and 41: Mains input Power regulation Contro
Page 42 and 43: Welding power source technology 29
Page 50 and 51: Three-phase transformer Three-phase
Page 52 and 53: Mains input Welding power source te
Page 54 and 55: Off line storage Operator interface
Page 58 and 59: 4.2.1 Improved toughness Filler mat
Page 60 and 61: Filler materials for arc welding 47
Page 62 and 63: Flat strip Solidified slag on weld
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Filler materials for arc welding 55
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Filler materials for arc welding 57
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Gases for advanced welding processe
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CVN impact energy (J) 200 150 100 5
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∑ argon plus 15-25% carbon dioxid
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25 23 21 19 17 15 13 11 9 7 20 18 1
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Ozone emission (ml min -1 ) 4 3 2 1
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Table 5.3 Continued Argon + 1 to 7%
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Advanced gas tungsten arc welding 7
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Power source Advanced gas tungsten
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Number of arc starts 35 30 25 20 15
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Water cooling 6.7 Dual-shielded GTA
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∑ low current: 0.1-15 A; ∑ inte
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Surface tension Surface tension Adv
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7.2.1 Globular drop transfer Metal
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Gas metal arc welding 103 projected
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Droplet forming 7.6 Drop spray tran
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Number of counts 100 80 60 40 20 0
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Metal cored Rutile Basic Self-shiel
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F d Fem F v F st F g 7.13 Balance o
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Gas metal arc welding 113 is the cu
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Stick out Dip transfer Pulse/spray
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Gas metal arc welding 117 V = M + A
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Voltage (V) 50 40 30 20 10 Gas meta
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Pulse current t p 7.23 Pulsed trans
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Gas metal arc welding 123 The mean
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Wire feed rate (m min -1 ) 11 10.5
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Gas metal arc welding 127 Improveme
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Gas metal arc welding 129 and a num
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Current (A) 500 400 300 200 100 0 G
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Pulse amplitude (A) 500 400 300 200
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Gas metal arc welding 135 otherwise
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High-energy density processes 137
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High-energy density processes 139 P
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Arc voltage 30 25 20 15 10 High-ene
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High-energy density processes 143 N
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Reflecting mirror Laser cavity Powe
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High-energy density processes 147 H
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Laser beam Gas lens Plasma control
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High-energy density processes 151 P
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High-energy density processes 153 M
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High-energy density processes 155 a
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High-energy density processes 157 l
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High-energy density processes 159 p
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8.4.5 Practical considerations High
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Sliding particle stop Undeflected b
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9.1 Introduction 9 Narrow-gap weldi
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6-16 mm Parallel-sided with backing
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Water cooling Main Shielding-gas po
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Narrow-gap welding techniques 171 T
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9.7 ‘Twist arc’ narrow-gap GMAW
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GMAW torch The NOW process GMAW tor
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Narrow-gap welding techniques 177 T
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10.1 Introduction 10 Monitoring and
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Monitoring and control of welding p
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PROJECT: WELDING CODE : WELDING PRO
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TYPE TOUGHNESS TEST TYPE No. TEMP R
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Data RAM ADC I/O device Monitoring
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Current I(A) 150 140 130 120 110 Mo
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Table 10.5 Stability criteria Monit
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CCD camera Travel direction Torch M
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Welding automation and robotics 219
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Table 11.1 Robot applications Weldi
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∑ evaluate alternatives; ∑ eval
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Option Manual metal arc Gas metal a
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Appendices Appendices 247
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Arc Metal arc Manual metal arc Resi
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Tensile strength Appendices 251 Des
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Appendices 253 Exx16 Basic low-hydr
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GMAW stainless steel c Wire feed sp
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Appendix 4 American, Australian and
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Appendices 259 Carbon Manganese ste
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Consumable type Features Applicatio
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Appendix 7 Plasma keyhole welding o
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References [1] British Standards In
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References 267 [40] Anon, 1989 ‘S
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References 269 [88] Boughton P and
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References 271 Century Conference (
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References 273 [178] Benn B, 1988
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References 275 [224] Philpott M L,
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References 277 [269] UK Patent 8411
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Activated TIG (A-TIG) 91, 97 adapti
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digital measuring systems 189-90 di
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high-frequency high-voltage arc ini
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current measurement 194-6 determina
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carbon dioxide 63-4, 64-6 chlorine
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