Introduction to Non-Arc Welding Processes

Module 2B Module 2 – Welding and Cutting Processes Introduction to Non-Arc Welding Processes

ƒ Non-Arc Welding processes refer to a wide range of processes which produce a weld without the use of an electrical arc

z High Energy Density Welding processes Š Main advantage – low heat input Š Main disadvantage – expensive equipment

z Solid-State Welding processes Š Main advantage – good for dissimilar metal joints Š Main disadvantage – usually not ideal for high production

z Resistance Welding processes Š Main advantage – fast welding times Š Main disadvantage – difficult to inspect

2-2 Module 2 – Welding and Cutting Processes Non-Arc Welding Introduction Introduction to Non-Arc Welding Processes

ƒ Brazing and Soldering z Main advantage – minimal degradation to base metal properties z Main disadvantage – requirement for significant joint preparation ƒ Thermite Welding z Main advantage – extremely portable z Main disadvantage – significant set-up time ƒ Oxyfuel Gas Welding z Main advantage - portable, versatile, low cost equipment z Main disadvantage - very slow

ƒ In general, most non-arc welding processes are conducive to original fabrication only, and not ideal choices for repair welding (with one exception being Thermite Welding)

2-3 High Energy Density (HED) Welding

Module 2B.1 Module 2 – Welding and Cutting Processes High Energy Density Welding Types of HED Welding

ƒ Electron Beam Welding z Process details z Equipment z Safety ƒ Laser Welding z Process details z Different types of lasers and equipment z Comparison to Electron Beam Welding z Hybrid Laser Welding z Safety

2-5 Module 2 – Welding and Cutting Processes High Energy Density Welding HED Welding

ƒ Power density (power / area) is significantly higher than that achieved by the common arc welding processes

ƒ In HED processes the power density is greater than 5 x 102 kW/cm2: z Electron Beam Welding z Laser Beam Welding z Plasma Arc Welding

2-6 Module 2 – Welding and Cutting Processes High Energy Density Welding Range of Power Densities

ƒ Depends on the power and spot size ƒ Melting and vaporization processes will be dominant in the molten pool kW/cm2 ƒ Vaporization may cause keyhole formation 106 105 104 103 EBW PAW Laser 2 2 10 Arc CO 10 100

2-7 Module 2 – Welding and Cutting Processes High Energy Density Welding HED Welding

ƒ Laser and electron beams can be focused to a very small spot size (the diameter of human hair, 0.05 mm) ƒ CW (constant wave) power density can reach as high as 105 kW/cm2 ƒ HED processes can melt and/or vaporize materials including: z Metals and alloys z Plastics and composites z Wood z Rubber z Ceramics and Concrete

2-8 Module 2 – Welding and Cutting Processes High Energy Density Welding HED Welding Applications

ƒ Automotive z Transmission components z Structural ƒ Aerospace z Jet Engines ƒ Medical z Pacemakers z Batteries ƒ Electrical z Relays z Electronic Devices

[Source: Internet]

2-9 Module 2 – Welding and Cutting Processes High Energy Density Welding HED Welding

ƒ Advantages (compared to Arc Welding processes) z Low overall heat input results in low distortion and minimal degradation to the base metal microstructure (small heat affected zone) z Very fast single pass weld speeds possible z Easily automated in the case of Laser Welding z Non-contact processes , no tool or electrode wear z No filler metal required ƒ Disadvantages z Accurate joint positioning and fit-up required z High equipment cost z Safety concerns

2-10 Module 2 – Welding and Cutting Processes High Energy Density Welding Welding Processes Comparison

Quality LBW EBW Arc Resistance Welding ++ ++ - + Speed Low Heat ++ ++ - + Input Narrow HAZ ++ ++ - - Weld Bead ++- Appearance Deep +++- - Penetration Equipment --++ Cost Equipment +++ Reliability + = Advantage - = Disadvantage

2-11 Module 2 – Welding and Cutting Processes High Energy Density Welding Relative Joining Efficiencies

Process Joining Efficiency mm2/kJ High Frequency Resistance Welding 65 - 100 Electron beam (EBW) 20 – 30 Laser (LBW) 15 - 25 Submerged arc welding (SAW) 4 – 10 Shielded metal arc (SMAW) 2 - 3 Gas tungsten arc welding (GTAW) 0.8 - 2 Oxyacetylene flame 0.2 - 0.5

[Ref: “Laser Material Processing”, W. M. Steen]

2-12 Module 2 – Welding and Cutting Processes High Energy Density Welding Power Densities and Weld Profiles

ƒ Flux shielded arc welding 0.5 - 50 kW/cm2

ƒ Gas shielded arc welding 0.5 -50 kW/cm2

ƒ Plasma 50 - 5×103 kW/cm2

ƒ Laser or electron beam 5×103 -5×105 kW/cm2

[Ref: “Laser Material Processing”, W. M. Steen]

2-13 Module 2 – Welding and Cutting Processes High Energy Density Welding HED Welding Features

ƒ Pressure on weld pool surface forms a deep depression (keyhole) ƒ Weld depth is generally significantly greater than width

Keyhole in Electron Beam Welding

[Ref: “AWS Handbook, Vol. 3, Welding Processes, Part 2, 9th Ed.] 2-14 Module 2 – Welding and Cutting Processes High Energy Density Welding “Keyhole” Formation

Laser Beam Keyhole

Work piece

2-15 Module 2 – Welding and Cutting Processes High Energy Density Welding Weld Joint Design for HED Welding

ƒ Butt, corner, lap, edge and T-joints can be made by Beam Beam electron beam welding using square-groove or seam welds. Square-groove weld ƒ Fillet welds are difficult to butt joint make and are not Edge weld, corner generally used. flange joint Beam Beam

Square-groove weld, Seam weld, T-joint lap joint

2-16 Module 2 – Welding and Cutting Processes Electron Beam Welding Electron Beam Welding (EBW) – Concept

Emitter (Cathode)

Grid (Bias Cup) Accelerating Electrode (Anode) Magnetic Focusing Lens

Magnetic Deflection Coil Workpiece

2-17 Module 2 – Welding and Cutting Processes Electron Beam Welding Control of the Electron Beam

ƒ Electron beam systems employ an electromagnetic lens to focus the electron beam into a small spot on the workpiece ƒ The deflection coils are generally positioned below the focusing lens, and are used to deflect the electron beam from its normal axial position

Deflection range Focus depth

2-18 Module 2 – Welding and Cutting Processes Electron Beam Welding Electron Beam Welding – Key Variables

ƒ Factors that affect electron beam welds z Electron-beam gun design z Focusing z Accelerating voltage z Beam current z Welding speed z Vacuum environment

2-19 Module 2 – Welding and Cutting Processes Electron Beam Welding Penetration as a Function of Operating Pressure in Electron Beam Welding ƒ HV – Hard Vacuum ƒ MV – Medium Vacuum ƒ NV – Non-Vacuum 100%

80%

60%

40% 10 -7 10 -6 .5x10 -5 torr 20%

0% 1 × 10-3 2 × 10-2 2 × 10-1 50 760 mmHg partial quick 1 x 10 -4 2 x 10 -4 3 x 10 -4 torr HV MV NV

[Ref: “AWS Handbook, Vol. 3, Welding Processes, Part 2, 9th Ed.]

2-20 Module 2 – Welding and Cutting Processes Electron Beam Welding Effect of Electron Beam Focusing on Weld Bead Geometry and Penetration

[Ref: “AWS Handbook, Vol. 3, Welding Processes, Part 2, 9th Ed.] 2-21 Module 2 – Welding and Cutting Processes Electron Beam Welding Electron Beam Safety

ƒ Electric shock risk due to extremely high voltages ƒ X-rays which are generated when beam contacts parts being welded ƒ Fumes and gases ƒ Visible radiation from intense heating

2-22 Module 2 – Welding and Cutting Processes Electron Beam Welding ASME Section IX – Electron Beam Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 φ Cross Section or Speed X .2 < t or φ Composition X .8 ± or φ Composition X .14 ± Filler X .20 φ Method of Addition X QW-404 Filler .21 φ Analysis X Metals .33 φ Classification X QW-408 Gas .6 φ Environment X

2-23 Module 2 – Welding and Cutting Processes Electron Beam Welding ASME Section IX – Electron Beam Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential φ I, E, Speed, Distance, QW-409 .6 Osc. X Electrical Characteristics .7 φ Pulsing Frequency X .5 φ Method of Cleaning X .14 φ Angle or Beam Axis X .17 φ Type Equipment X .18 > Pressure of Vacuum X φ Filament Type, Size, QW-410 .19 etc. X Technique .20 + Wash Pass X

2-24 Module 2 – Welding and Cutting Processes Laser Welding Laser Beam Welding (LBW)

ƒ The word “LASER” is an acronym for “light amplification by stimulated emission of radiation” ƒ A focused Laser Beam Welding (LBW) machine is an excellent source of concentrated power ƒ Three basic types of lasers are used in welding: gas (CO2), solid-state lasers ((),Nd:YAG), fiber

2-25 Module 2 – Welding and Cutting Processes Laser Welding Comparison of LBW to EBW

ƒ No vacuum requirement for LBW – much more conducive to high speed production ƒ Very flexible beam deliver systems with LBW – ease of automation ƒ No X-ray hazards with LBW, but eye safety is important ƒ EBW capable of welding much thicker cross-sections

2-26 Module 2 – Welding and Cutting Processes Laser Welding Three Important Laser Components

ƒ Laser gain medium ƒ Pumping energy ƒ Optical resonator cavity

Nd: YAG solid-state laser

Partially reflective mirror

Flashlamp (pump source)

Highly reflective Laser output mirror

Nd:YAG crystal (laser medium)

Optical resonator 2-27 Module 2 – Welding and Cutting Processes Laser Welding

CO2 Lasers

Laser

CO2 + N2 + He Laser beam

Electron stream

ƒ Electrical current passes through a low pressure gas mixture of CO2, nitrogen and helium to excite gas molecules, obtain a population inversion

ƒ Most CO2 lasers produce either a continuous wave (CW) or pulsed output. z The pulses are generated by periodically interrupting the energy input to the laser cavity

2-28 Module 2 – Welding and Cutting Processes Laser Welding Nd:YAG Lasers

ƒ Lasing medium for the Nd:YAG laser is a transparent rod of yttrium aluminum garnet crystal implanted with neodymium ions ƒ Laser cavity consists of lamps, mirror reflector and YAG rod ƒ Nd:YAG laser has a wavelength of 1.06 mm ƒ Advantages over CO2 laser output z Optical fiber delivery, easy to adapt to robotics z Increased absorption in metals

2-29 Module 2 – Welding and Cutting Processes Laser Welding Fiber Lasers

5kW Single Mode

Multiple 1kW single Multi-KW mode fibers interfaced Multi-Mode to a larger multi-mode fiber by a patented technique

2-30 Module 2 – Welding and Cutting Processes Laser Welding Laser Beam Focusing

ƒ Focal spot diameter of a high power laser beam is best measured with an optical instrument but can be estimated by spot welds or holes ƒ Standard optical formulae z Focal point diameter » M2 4lf/(pD) z Depth of focus = 4M2lf 2/(pD 2)

D

f λ- Wavelength, M 2 – beam quality factor

ds – spot diameter, 2-31 Module 2 – Welding and Cutting Processes Laser Welding Laser Beam Focusing

2-32 Module 2 – Welding and Cutting Processes Laser Welding Types of Laser Optics

ƒ The higher power lasers generally employ reflective style optics Windows z Mirrors ƒ These mirrors are usually water cooled to withstand high incident powers Output couplers ƒ They may be either bare or coated ƒ Highly polished, bare copper mirrors are commonly employed, but gold- Mirrors coated mirrors will provide the highest reflectivity

2-33 Module 2 – Welding and Cutting Processes Laser Welding Fiber Optics

ƒ Working distances up to 150 m ƒ Can reach difficult-to-access places ƒ Can be taken under water Launch Optics Focus Mirror ƒ Multi-station operation ƒ Robotics applications ƒ Flex ibility

2-34 Module 2 – Welding and Cutting Processes Laser Welding Laser Safety

ƒ Carbon dioxide laser machines have a good industrial safety record ƒ Very few serious beam related accidents reported ƒ Certain lasers such YAG and Fiber Lasers require special eye protection to filter out their dangerous wavelength ƒ Danger associated with high voltage system used to generate the electrical discharge ƒ Lasers pose serious eye and burn hazards

2-35 Module 2 – Welding and Cutting Processes Laser Welding ASME Section IX – LBW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 φ Cross Section or Speed X .2 < t or φ Composition X .8 ± or φ Composition X .14 ± Filler X .20 φ Method of Addition X QW-404 Filler .21 φ Analysis X Metals .33 φ Classification X .2 φ Single, Mixture, or % X .6 φ Environment X .11 ± Gases X

QW-408 .12 φ > 5% Gases X Gas .13 φ Plasma Jet Position X

2-36 Module 2 – Welding and Cutting Processes Laser Welding ASME Section IX – LBW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .19 φ Pulse X

QW-409 .20 φ Mode, Energy X Electrical φ Power, Speed, D/fl, Characteristics .21 Distance X .5 φ Method of Cleaning X .14 φ Angle or Beam Axis X

QW-410 .17 φ Type Equipment X Technique .20 + Wash Pass X

2-37 Module 2 – Welding and Cutting Processes Hybrid Laser Welding Hybrid Laser Welding

ƒ Reflects a recent trend toward combining two welding processes into one ƒ Very common approach is to combine LBW and GMAW ƒ Utilizes the advantages of each process and minimizes the disadvantages z High welding speed of LBW z Wider weld profile of GMAW provides better tolerance to weld gap and alignment z Laser stabilizes arc z Flexibility of fiber delivery with LBW z Capability for weld reinforcement with GMAW

[Courtesy: EWI] 2-38 Module 2 – Welding and Cutting Processes Hybrid Laser Welding Hybrid Laser Welding

ƒ Laser beam “leads” the weld puddle Laser GMAW ƒ Laser spot stabilizes the arc Beam ƒ Laser and GMAW is the most Laser Shielding Plume Gas common hybrid process, but other Fusion Keyhole Zone combinations are being explored

ƒ ASME Section IX is currently working to incorporate laser hybrid as a welding process

Hybrid Weld in Aluminum

[Courtesy: EWI] 2-39 Module 2 – Welding and Cutting Processes Hybrid Laser Welding Hybrid Laser GMAW

2-40 Solid-State Welding

Module 2B.2 Module 2 – Welding and Cutting Processes Solid-State Welding Introduction Solid-State Welding Overview

ƒ A group of welding processes that produces a metallurgical bond between two metals at temperatures below the melting point of the base metal”

ƒ Fundamentals z Metallic bonding z Barriers to bonding z Overcoming barriers to bonding z Roll bonding theory ƒ Processes z Friction Welding z Diffusion Welding z Explosion Welding z Ultrasonic Welding

2-42 Module 2 – Welding and Cutting Processes Solid-State Welding Introduction Advantages Compared to Arc Welding Processes

ƒ Elimination of molten metal reduces the chance for forming weld defects ƒ Dissimilar metal joints are possible ƒ Usually produces very high quality, high strength weld joints ƒ Consumables such as filler metals and shielding gas are not required ƒ Often used for welding materials that cannot be welded with conventional welding processes

2-43 Module 2 – Welding and Cutting Processes Solid-State Welding Introduction Disadvantages Compared to Arc Welding Processes ƒ Usually requires expensive equipment ƒ Not always conducive to high production ƒ Significant joint preparation is sometimes required ƒ Limited joint designs ƒ Non-destructive inspection can be difficult

2-44 Module 2 – Welding and Cutting Processes Solid-State Welding Introduction Applications

ƒ Jet engines ƒ Automotive components ƒ Cookware ƒ Electrical devices ƒ Microelectronics ƒ HtHeat exc hangers ƒ Medical products ƒ Many more!

[Source: Internet]

2-45 Module 2 – Welding and Cutting Processes Solid-State Welding Principles Metallic Bonding

ƒ Valence electrons are not bound to a single atom and are free to drift (which is why metals conduct electricity) to form a “cloud” of electrons Ion cores Valence electron cloud ƒ Remaining non-valence electrons and atomic nuclei form ion cores ƒ The binding forces between the ion cores and electron cloud hold the atoms together

2-46 Module 2 – Welding and Cutting Processes Solid-State Welding Principles Metallic Bonding

ƒ Driving force for bonding of metals: z Adhesion, (formation of metallic bonds) between two metal surfaces can occur due to inter-atomic forces described previously z To occur, the two surfaces must be brought extremely close together ~ 10 A – a nearly perfectly smooth surface! z No industrial process is capable of achieving such a smooth surface

Attraction Approx. 10 A

Force r Repulsion Inter-atomic separation

2-47 Module 2 – Welding and Cutting Processes Solid-State Welding Principles Metallic Bonding

ƒ If there is a driving force for welding, why aren’t metals easily welded with Solid-State Welding Processes? z Barriers to bonding hinder intimate contact: Š Asperities (surface roughness) Š Oxides Š Surface contamination

2-48 Module 2 – Welding and Cutting Processes Solid-State Welding Principles Interfaces - Asperities

ƒ Barriers to Solid-State Welding – asperities z High and low areas of metal surfaces z Prevent intimate contact z All metals will have some surface roughness Asperities

2-49 Module 2 – Welding and Cutting Processes Solid-State Welding Principles Interfaces - Oxides

ƒ Barriers to Solid-State Welding – oxides z Most metals react with atmosphere and form oxide films z Oxide films are hard and brittle and interfere with metal-to-metal contact z Sufficient deformation is required to break up oxide films during Solid- State Welding Oxide film on metal

2-50 Module 2 – Welding and Cutting Processes Solid-State Welding Principles Interfaces - Contamination

ƒ Barriers to Solid State Welding - surface contamination: z Oils, scales, grease, etc. z Adhere to surface by secondary bonding z Reduce metal-to-metal contact z Must be removed prior to welding, or during the Solid-State Welding process being utilized

2-51 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Roll Bonding

ƒ Roll bonding theory z Roll bonding introduces nascent surface – new metal-to-metal surfaces formed during plastic deformation z Asperities are collapsed and oxides broken up z Increased nascent surface results in increased weld strength z This theory is describes the main objective of most Solid-State Welding processes Š Create nascent surfaces Nascent Surface Original interface

Roll bonding produces nascent surfaces needed for Solid-State Welding

2-52 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Friction Welding Processes

ƒ Processes – Friction Welding z Inertia Friction Welding Š Inertia of rotating flywheel generates heat z Continuous Drive Friction Welding Š Continuous drive system (i.e. hydraulic) for more precise control of rotational velocity and frictional heating z Friction Stir Welding Š Non-consumable pin rotated along joint to produce frictional heating z Linear Friction Welding Š Linear translation of parts in contact with each other produces frictional heating

2-53 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Friction Welding Processes

ƒ Friction Welding – Advantages z Extremely reproducible, high quality joints z Fewer variables than most welding processes z Forging action reduces need for joint preparation z Ideal for joining dissimilar materials z Easily automated for high volume production z Can join plastics

2-54 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Friction Welding Processes

ƒ Friction Welding – Disadvantages z Equipment cost is high z Application limited by part geometry and size z Some processes (i.e. Friction Stir Welding are slow) z Difficulty in joining dissimilar materials with large differences in properties

2-55 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Friction Welding Processes

ƒ Rotational Friction Welding Processes z Inertia and Continuous Drive Friction Welding Š Ideal for round bars and shapes Š One part is rotated at high speed relative to other part Š Parts are brought together, axial force is applied creating frictional heating Š Softened material is upset into the “flash”, which is later removed

2-56 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Inertia Friction Welding (IFW)

ƒ Utilizes kinetic energy of rotating flywheel ƒ Flywheel connected to one part while other remains stationary ƒ Flywheel rotational velocity ggyradually decreases as joint cools and gains strength ƒ Additional forge force is added at the end of the cycle ƒ Ideal process for large parts z Common in jet engine manufacturing

[Ref.: AWS Welding Handbook, Vol. 3, 9th Ed.]

2-57 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Continuous Drive Friction Welding (CDFW)

ƒ Motor driven ƒ Rotational speed is controlled and held constant during the heating stage ƒ Provides better control of welding variables vs. Inertia Welding ƒ Also referred to as Direct Drive Friction Welding

[Ref.: AWS Welding Handbook, Vol. 3, 9th Ed.] 2-58 Module 2 – Welding and Cutting Processes Solid-State Welding Processes ASME Section IX – IFW and CDFW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential φ ± 10 deg X φ Cross Section > 10% X

QW-402 φ O.D. > ± 10% X Joint .12 φ Solid-to-tube X QW-408 Gas .6 φ Environment X .27 φ Spp. > ± 10% X .28 φ Load > ± 10% X

QW-410 .29 φ Energy > ± 10% X Technique .30 φ Upset > ± 10% X

2-59 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Friction Stir Welding

ƒ Rotating tool is moved along top of the joint creating frictional heat and plasticized material in the stir zone ƒ Provides the ability to produce solid-state friction welds in a butt joint configuration between two plates ƒ Ideal for welding materials which are difficult to weld using fusion weldinggp processes

ƒ ASME Section IX is currently working to incorporate friction stir as a welding . process Pin

2-60 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Friction Stir Welding

ƒ Friction Stir welds consist of three distinct “zones”: z Stir zone or nugget z Heat and deformation affected zone (HDAZ) or thermo-mechanically affected zone (TMAZ) z Heat affected zone (HAZ)

2-61 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Linear Friction Welding

ƒ Linear motion between two parts Force creates frictional heating and solid- state weld ƒ Provides for flexibility of part geometry Rapid linear motion ƒ Sometimes referred to as Translational Friction Welding ƒ Another variation utilizes orbital motion

Force

2-62 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Diffusion Welding

ƒ A welding process that creates a solid-state weld through the application of pressure at elevated temperatures

ƒ Advantages Pressure z Negligible deformation z Low heat process – minimal microstructure degradation Part A ƒ Disadvantages Part B z Significant surface preparation required z Long weld times Elevated Temperature Furnace

2-63 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Diffusion Welding

ƒ Stage 1 – initial asperity contact

Deformation, interfacial Asperity contact ƒ Stage 2 – deformation boundary formation and formation of interfacial boundary ƒ Stage 3 – grain boundary migration, elimination of interfacial boundary, pore

Grain boundary migration, Volume diffusion, further elimination pore elimination pore elimination ƒ Stage 4 – volume diffusion, further elimination of interfacial boundary and pores

2-64 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Explosion Welding

ƒ A welding process that creates a solid-state weld through high velocity interaction of the work pieces by a controlled detonation

Detonator ƒ Advantages Explosive z Minimal heatinggp of the parts z Can produce almost any Standoff dissimilar metal combination distance Prime ƒ Disadvantages component z Not conducive to production Base z Limited joint designs component Arrangement for Explosion Welding

2-65 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Explosion Welding

ƒ Principals of Explosion Welding Detonation z Explosive is distributed over top surface of prime component z Upon detonation, high velocity collision occurs between prime Prime and base component Weld component z “Jetting” provides for cleaning Jet action and proper weld formation

Base component

2-66 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Ultrasonic Welding

ƒ A welding process that produces a solid-state weld through the application of high frequency vibrations combined with low pressure

ƒ Advantages: z Negggligible heatin g of parts z Minimal deformation ƒ Disadvantages z Limited to lap joints z At least one component must be very thin Typical Ultrasonic Welding Machines

[Source: Internet]

2-67 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Ultrasonic Welding

Clamping Principals of Ultrasonic force ƒ Welding z A static clamping force is Mass applied perpendicular to the interface between the work pieces Wedge Transducer z The contacting sonotrode oscillates parallel to the Sonotrode interface tip z Combined effect of static and oscillating force produces Work pieces deformation which promotes welding

Anvil Force

2-68 Module 2 – Welding and Cutting Processes Solid-State Welding Processes Solid-State Welding

ƒ Some applicable specifications and recommended practices z AWS C6.1, “Recommended Practices for Friction Welding” z AWS C6.2, “Specification for Friction Welding of Metals” z ASME Section IX currently has requirements for only IFW and CDFW solid-state welding processes Š Requirements for Friction Stir Welding are being developed ƒ Very limited information in terms of codes, standards, and specifications z Solid-state weld development is typically based on applicable fusion welding codes

2-69 Resistance Welding

Module 2B.3 Module 2 – Welding and Cutting Processes Resistance Welding Introduction Resistance Welding Overview

ƒ Fundamentals z Resistivity and Heat Generation z Heat Balance ƒ Common processes z Spot Welding z Projection Welding z Seam Welding z Flash Welding

ƒ AWS has numerous resistance welding codes for different applications z AWS C1.1, “Recommended Practices for Resistance Welding” z AWS C1.4, “Specification for Resistance Welding of Carbon and Low Alloy Steels” z AWS D8.6, “Standard for Automotive Resistance Spot Welding Electrodes” 2-71 Module 2 – Welding and Cutting Processes Resistance Welding Introduction Definition of Resistance Welding

ƒ The electrical resistance of metal and metal-to-metal contact area to the localized flow of current produces 2 × heat (Joule heating = I Rt) at the joint ƒ This heating, combined with pressure produces a weld ƒ Welds may be fusion or solid-state welds

Spot welding

2-72 Module 2 – Welding and Cutting Processes Resistance Welding Introduction Resistance Welding Applications

ƒ Automotive z Bodies z Frames z Components ƒ Medical ƒ Tubing ƒ Appliances ƒ Electrical ƒ Light manufacturing z Fencing z Grills z Chains [Source: Internet] z Office products ƒ “Every metal product is a possible application” – RWMA

Handbook 2-73 Module 2 – Welding and Cutting Processes Resistance Welding Fundamentals Resistance Welding Fundamentals – Resistivity at Joint

Ideal Resistance Welding conditions occur when resistance #4 is maximized relative to other 6: Force 7 “resistors” in a Resistance Welding circuit:

1 CtCurrent

2 Copper 3 electrodes Work Pieces 4 5 6 Distance

7 Resistance Force 2-74 Module 2 – Welding and Cutting Processes Resistance Welding Fundamentals Resistance Welding Fundamentals – Effect of Pressure

High Resistance Low Resistance

Surface Asperities

Low Pressure Medium Pressure High Pressure

2-75 Module 2 – Welding and Cutting Processes Resistance Welding Fundamentals Resistance Welding Fundamentals – Effect of Pressure

Resistance highly dependent on electrode force

Δ R1 Log Scale)

Resistance nearly independent of electrode force Δ R2 Contact Resistance ( Contact Resistance ΔF ΔF Electrode Force (Linear Scale)

2-76 Module 2 – Welding and Cutting Processes Resistance Welding Fundamentals Resistance Welding Fundamentals – Lobe Curves

One method for generating Lobe Expulsion Curves is to use Acceptable nugget diameter Nuggets as an indicator of weld quality Minimum Nugget Diameter get Diameter get gg Nu Small Nuggets Time A Weld Current

Time A Lobe Curve Smaller Expulsion Weld Time Weld “Brittle” Acceptable Level Nuggets Nuggets

Weld Current

2-77 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Spot Welding

Water Weld Nugget Top Electrode

Bottom Electrode

2-78 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Spot Welding

ƒ Advantages z Ideal for high speed production of sheet metal assemblies z Easy to automate z Self-clamping z No filler materials required z Relatively inexpensive z “Aesthetics” of surface condition

2-79 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Spot Welding

ƒ Disadvantages z Overlapping joint adds weight z Need for sufficient joint access z Hidden weld location – quality control is difficult, highly dependent on Lobe curves z Poor mechanical properties due to notches and uneven load distributions z Expensive equipment z Weld repair difficult z Extreme power line demands

2-80 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Projection Welding

ƒ Applicability Force z Parts are too thick for Spot Welding z A significant (>5:1) size difference exists between parts z A significant electrical conductivity difference exists between parts ƒ Projection balances the heat z Concentrates current z Allows parts to reach the same temperature across the interface

Projection in part Electrodes

Current

2-81 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Projection Welding

ƒ Advantages z Ease of obtaining satisfactory heat balance for welding difficult combinations z Can weld greater thicknesses and thickness mismatches vs. Spot Welding z More uniform results in many applications z Increased output per machine because several welds are being made simultaneously z Longer electrode life z Welds may be placed more closely together z Parts are more easily welded in an assembly fixture z Finish, or surface appearance, is often improved on side without the projection z Parts may be projection welded that could not be otherwise resistance welded z Often replaces arc welding processes such as GMAW and results in much faster welding time 2-82 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Projection Welding

ƒ Disadvantages z Requires an additional operation to form projections z Requires accurate control of projection height and precise alignment of the welding dies with multiple welds z Requires higher capacity equipment than Spot Welding

2-83 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Projection Welding

ƒ Common projection designs z Button or Bubble Š Most common Š Easy to form with punch and die Š Usually involves forming multiple individual projections Button or Bubble Embossed Projection Design z Annular Š Single “ring” projection centered on the part ƒ Approaches to producing projections z Embossing or forming Š Least expensive Š Usually results in melting but not always z Machining Š Used when welding thicker parts Annular Solid Projection Design Š Referred to as solid projections Š Always a solid-state weld

2-84 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Seam Welding

ƒ Lap seam welding – same advantages as spot, but with ability to create continuous leak-tight joints – automotive gas tanks are a very common application ƒ Primary disadvantage is the requirement for straight or uniformly curved paths and uniform joint contours

[Ref.: AWS Welding Handbook, Vol. 3, 9th Ed.] [Source: Internet] 2-85 Module 2 – Welding and Cutting Processes Resistance Welding Processes ASME Section IX – Resistance Welding Process Procedure Variables

Paragraph Brief of Variables Essential Nonessential .13 φ Spot, Projection, Seam X

QW-402 .14 φ Overlap, Spacing X Joints .15 φ Project, Shape, Size X

QW-403 .21 ± Coating, Plating X Base Materials .22 ± T X QW-408 Gas .23 - Gases X

2-86 Module 2 – Welding and Cutting Processes Resistance Welding Processes ASME Section IX – Resistance Welding Process Procedure Variables

Paragraph Brief of Variables Essential Nonessential .13 φ RWMA Class X .14 ± φ Slope X .15 φ Pressure, Current, Time X QW-409 Electrical .17 φ Power Supply X Characteristics .18 Tip Cleaning X .31 φ Cleani ng Me tho d X .32 φ Pressure, Time X .33 φ Equipment X

QW-410 .34 φ Cooling Medium X Technique .35 φ Throat X

2-87 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Flash Welding

ƒ Not an arc welding process, but Clamping of parts a continuous series of high current density “shorts” ƒ Flash Welding steps z Clamp parts z Apply flashing voltage and initiate Platen movement platen motion z Continue flashing motion to achieve proper heating Platen movement z Terminate flashing and apply upset force to create solid-state weld

Upset force

[Ref.: AWS Handbook, Vol. 2, 8th Ed].

2-88 Module 2 – Welding and Cutting Processes Resistance Welding Processes Resistance Flash Welding

Flash Welding of Steel Tubes

[Courtesy: EWI] 2-89 Module 2 – Welding and Cutting Processes Resistance Welding Processes ASME Section IX – Flash Welding Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .19 φ Diameter or Thickness X .20 φ Joint Configuration X φ Method or Equip. used .21 to Minimize ID Flash X QW-402 φ End Preparation Joint .22 Method X φ Shielding Gas QW-408 Composition, Pressure, Gas .22 or Purge Time X

QW-409 .27 φ > 10% Flashing Time X Electrical φ > 10% Upset Current Characteristics .28 Time X

2-90 Module 2 – Welding and Cutting Processes Resistance Welding Processes ASME Section IX – Flash Welding Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .17 φ Type/Model of Equipment X φ > 10% Upset Length or .54 Force X φ > 10% Distance Between Clamping Dies or Preparation .55 of Clamping Area X .56 φ Clamping Force X QW-410 φ 10% Forward or Reverse Technique .57 Speed X

2-91 Thermite Welding

Module 2B.4 Module 2 – Welding and Cutting Processes Thermite Welding Thermite Welding

ƒ A welding process that produces coalescence of metals by heating them with superheated metal from an exothermic reaction between a metal oxide and aluminum ƒ Very portable, minimal capital quipment cost ƒ Does not require external power source ƒ Common applications z Rail z Reinforcing bar

Thermite Welding of rails [Ref: “AWS Handbook, Vol. 3, Welding Processes, Part 2, 9th Ed.] 2-93 Module 2 – Welding and Cutting Processes Thermite Welding Thermite Welding

ƒ Welding steel reinforcing bar z Provides for design of smaller concrete columns and beams z Relies on a closure disc at the base of the crucible which melts, allowing the molten steel to flow into the joint z Can be welded in any position z Schematic shows a version in which bars are not melted

Thermite sleeve joint for reinforcing bars

[Ref: “AWS Handbook, Vol. 3, Welding Processes, Part 2, 9th Ed.] 2-94 Module 2 – Welding and Cutting Processes Thermite Welding Thermite Welding Safety

ƒ Moisture must be minimized ƒ Work area should be free of combustible materials and well ventilated ƒ Personnel should wear appropriate protection – gloves, face shields with filter lenses, safety boots, and gloves ƒ No pockets or cuffs

2-95 Oxyfuel Gas Welding (OFW)

Module 2B.5

2-96 Module 2 – Welding and Cutting Processes Oxyfuel Gas Welding Oxyfuel Gas Welding

ƒ A group of welding processes that achieve the coalescence of metals by heating them with an oxyfuel gas flame - may or may not use a filler metal ƒ One of the oldest welding techniques (early 1900's) ƒ Mostly replaced by arc welding processes today, but still offers portability, versatility, and low equipment cost ƒ Very slow welding speeds, cannot be used with reactive metals

2-97 Module 2 – Welding and Cutting Processes Oxyfuel Gas Welding Oxyacetylene Welding

ƒ Most widely used OFW process ƒ Acetylene (C2H2) produces the heat and oxygen supports combustion ƒ Acetylene offers high combustion intensityyp compared to other fuel gases ƒ Welding equipment can easily be converted to cutting equipment with attachment ƒ Filler metals that match base metal chemistry are typically used ƒ Fluxes are used to assist in oxide removal during welding

2-98 Module 2 – Welding and Cutting Processes Oxyfuel Gas Welding Oxyfuel Gas Welding

ƒ Flame Adjustment

z Neutral flame - decrease Carburizing flame acetylene flow until feather disappears z Carburizing flame - contains acetylene "feather" Š Can be used to increase carbon content or reduce melting point of weld metal Neutral flame z Oxidizing flame - contains a reduced cone length

Oxidizing flame

2-99 Module 2 – Welding and Cutting Processes Oxyfuel Gas Welding Oxyfuel Gas Welding Safety

ƒ Compressed gases ƒ Flammable fuel gases…keep away from sources of ignition ƒ Acetylene can react violently with copper ƒ Goggles with proper shielding must be worn ƒ Use proper ventilation

2-100 Module 2 – Welding and Cutting Processes Oxyfuel Gas Welding ASME Section IX – OFW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .3 φ Size X .4 φ F-Number X QW-404 Filler .5 φ A-Number X Metals .12 φ Classification X QW-405 Positions .1 + Position X QW-408 Gas .7 φ Fuel Gas Type X .2 φ Flame Characteristics X

QW-410 .4 φ ← → Technique X Technique .5 φ Method of Cleaning X

2-101 Introduction to Brazing and Soldering

Module 2C Module 2 – Welding and Cutting Processes Brazing and Soldering Introduction AWS Definition of Brazing and Soldering

ƒ Joining processes which utilize a filler metal which melts below the melting temperature of the base metal z Brazing: filler metal liquidus > 450ºC z Soldering: filler metal liquidus < 450ºC ƒ Joint formation z Filler metal melting z Joint gap filled by capillary action z Filler metal solidifies

ƒ ASME Section IX has an entire section dedicated to qualifying brazing procedures and brazers which is not covered in this course z Follows the same methodology as welding procedure and welder qualifications

2-103 Module 2 – Welding and Cutting Processes Brazing and Soldering Introduction Elements of Brazing and Soldering

ƒ Materials z Base materials Š Metals and alloys: ferrous and non-ferrous Š Ceramics Š Glasses Š Composites z Filler metals ƒ Brazing and soldering processes z Heat sources: electrical, chemical (combustion, exothermic reactions) z Protection from oxidation: fluxes, controlled atmospheres z Equipment: torches, furnaces, inductors, baths, etc. Š Brazing: Al, Mg, Ag, Au, Cu, Ni, Co, Ti, Mo, and Nb based alloys Š Soldering: Sn, Pb, In, Au based, and Zn, Bi, and Cd containing alloys ƒ Joint design z Lap joints, butt joints z Joint clearance (gap) 2-104 Module 2 – Welding and Cutting Processes Brazing and Soldering Introduction Brazing and Soldering

ƒ Advantages z No melting of base metal z Able to easily join dissimilar metals and metal-to-non-metal combinations z Economical for complex assemblies and large joint designs z Minimal distortion and residual stress ƒ Disa dvan tages z Formation of brittle intermetallics z May require highly skilled operators z Difficulties with fit-up and assembly

2-105 Module 2 – Welding and Cutting Processes Brazing and Soldering Introduction Brazing and Soldering – Applications

ƒ Electrical and electronic components ƒ Automotive ƒ Aerospace ƒ Solar panels ƒ Nuclear systems ƒ FdFood process ing equ ipmen t ƒ Pressure vessels ƒ Jewelry ƒ Toys

[Source: Internet] 2-106 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Joint Formation

ƒ Filler metal melting, wetting and gap filling, solidification ƒ Base/filler metal reactions z During brazing/soldering z During aging (at service temperature) Š Dissolution Š Diffusion Š Formation of intermetallic compounds Š Formation of solid solutions

Typical Braze/Solder Joint

[Ref.: “Brazing Handbook, 5th Ed.”, AWS] 2-107 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Wetting

ƒ Surface energy balance Vapor / Gas γ ƒ Assumptions LV z No chemical reactions Liquid γ z No gravity θ SV γ ƒ Spreading, if θ ~ 0º Solid SL ƒ Wetting, if θ <90< 90º ƒ No wetting, if θ > 90º ƒ Brazing and soldering optimum: 10º ≤ θ≤ 45º ƒ Effect of oxides and surface active impurities (γ −γ ) cosθ = SV SL γ LV

z θ – contact angle z γ – surface energy

2-108 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Capillary Action

ƒ Factors controlling capillary action

z Wetting (θ, γLV) z Liquid density z Liquid viscosity z Gap distance and geometry z Surface cleanliness

Capillary Action Principle

2-109 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Fluxes

ƒ Functions z Remove surface oxides z Protect from surface oxidation during brazing / soldering z Reduce surface tension of molten filler metal ƒ Composition z Active component Š Reducing or etching, acids or alkaline metals (F, Cl, Li, B) z Solvent Š Water or alcohol z Wetting agents Š Organic compounds

2-110 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Brazing Fluxes

Brazing Fluxes: Examples from AWS A5.31 Specification

AWS Form Filler metal Ingredients Temp. Process Base material Clas. type range, oC FB1-A Powder BAlSi Fluorides, 560-615 Torch, Furnace Brazeable Al alloys Chlorides FB2-A Powder BMg Fluorides, 480-620 General purpose Mg alloys designated Chlorides with AZ FB3-C Paste BAg, Borates, 565-925 General purpose BCuP Flourides, B FB3-G Slurry BAg, Borates, 565-870 General purpose Brazeable metallic BCuP Flourides alloys except containing Al and Mg, FB3-K Liquid BAg, Borates 760-1205 Torch flux applied carbides BCuP by fuel gas RBCuZn

2-111 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Soldering Fluxes

Soldering Fluxes: Examples from ANSI/J-STD 004

Flux Material Activity Level (% Halide) Type ANSI Designator

Rosin (RO) Low (0%) L0 ROL0 Resin (RE) Low (<0.5%) L1 REL1 Organic (OR) Moderate (0.5-2.0%) M1 ORM1 Inorganic (IN) High (>2.0%) H1 INH1

ISO classification: 122C Resin–base flux Soldering Fluxes: Examples from ISO 9454-1 with halogen activator Flux Type Flux Basis Flux Activation Flux Form 1 Resin 1 Rosin 1 Nonactivated A Liquid 2Resin 2 Halogen activated 2 Organic 1 Water Soluble 3 Not halogen activated 2 Not Water Soluble B Solid 3 Inorganic 1 Salts 1 With ammonium chloride 2 With ammonium chloride 2 Acids 1 Phosphoric acid C Paste 2 Other acids 3 Alkalis 1 Ammonia and/or amines

2-112 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Brazing and Soldering Filler Metals

ƒ Liquidus temperature z Lower than base material z > 450ºC in brazing filler metals z < 450ºC in soldering filler metals ƒ Requirements z Wetting Š Spreading and adhering to substrate z Melting temperature range Š Clearance filling by capillary action z Homogeneous composition Š Avoid liquation The Tin-Lead Binary Phase Diagram z Mechanical and physical properties [Ref: “Soldering Handbook”, 3rd Ed., AWS] z Interactions with base material Š Brittle compounds, erosion, etc. Š Diffusion, chemical reactions 2-113 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Brazing and Soldering Filler Metals

0 0 Melting Temperature 450 C (840 F)

Soldering Filler Metals Brazing Filler Metals

[Ref: “Principles of Soldering and Brazing”, ASM International]

2-114 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Brazing Filler Metals

Classes of Brazing Filler Metals from AWS A5.8/A5.8M

Class Alloy Family AWS Des. Materials Joined Application Examples

1 Al-Si BAlSi Aluminum and aluminum to steel and beryllium Car radiators, heat exchangers, aircraft honeycomb structure

2 Cu-X BCu Copper and copper to steel and stainless steel Heat exchangers, automotive parts

3 Cu-Zn RBCuZn

- Cu-Sn None

4 Cu-P BCuP Copper and copper to silver/oxide metal composites Electrical components, heat exchangers

5 Cu-Ag Bag Most metals except aluminum and magnesium Most widely used utility filler metal

6 TM-Si-B BNi Steels, copper, nickel, and cobalt-base alloys Aircraft and automotive parts, heat exchangers, honeycomb

7 (Co,Cr)-Si-B BCo Steels, cobalt-base alloys Aircraft engines, honeycomb marine structures

- (Ni,Pd)-Si-B None Stainless steels, superalloys, and cemented carbide Honeycomb, orthodontics, catalytic convertors

8 Au-Ni BAu Nickel-based alloys, steels Honeycomb structures, turbine parts - Cu-(Ti,Zr)-Ni None Titanium and zirconium-based alloys Aircraft components, chemical reactors

2-115 Module 2 – Welding and Cutting Processes Brazing and Soldering Fundamentals Soldering Filler Metals

ASTM B32-91: Standard Specification for Solder Metal ISO/DIS 9453, ISO/CD 12226-1, ISO/CD 12224-1

Compositions Forms Sn Based: Sn, Sn-Pb; Sn-Pb-Sb; Sn-Pb-Ag; Pb-Ag Bars SN Based, Pb Free: Sn-Sb; Sn-Sb-Ag-(Cu); Sn-Ag Paste Zn Containing: Sn-Zn; Zn-Al; etc. Solid Wire In Based: In; In-Sn; In-Pb; etc. Flux Cored Wire Bi Containing Foil, Sheet, Ribbon Au Based Segment or Drop

Cd Containing Cakes or ingots: 3 to 10 lb Pig: 50 to 100 lb

2-116 Module 2 – Welding and Cutting Processes Brazing and Soldering Processes Brazing and Soldering Processes

Brazing Processes Soldering Processes Torch Torch Induction Induction Furnace Furnace Dip (Immersion) Dip (Immersion) Resistance Vapor Phase Diffusion Resistance Laser Beam Laser Beam Electron Beam Hot Gas Exothermic Ultrasonic Infrared

2-117 Module 2 – Welding and Cutting Processes Brazing and Soldering Processes Torch Brazing / Soldering

ƒ Low to moderate capital cost ƒ Flexible component sizes ƒ Used with flux or self-fluxing alloys ƒ Manual and mechanized ƒ Applications z Carbon steel z Stainless steel z Cast iron z Copper z Aluminum z Carbides ƒ Flame characteristics

[Ref: “Brazing Handbook”, 5th Ed., AWS]

2-118 Module 2 – Welding and Cutting Processes Brazing and Soldering Processes Induction Brazing / Soldering

ƒ Low to moderate capital cost ƒ Used with flux or atmospheres ƒ Best for small components ƒ High speed ƒ Localized heating ƒ Therma l cyc le con tro l ƒ Applications z Carbon and stainless steel ρ z Cast iron d =3160 ,in z Copper μ⋅ f z Aluminum μ z Titanium = 1 above curie temperature or for non-magnetic materials ρ = electrical resistivity f = frequency, Hz

2-119 Module 2 – Welding and Cutting Processes Brazing and Soldering Processes Furnace Brazing / Soldering

ƒ High capital and operation cost ƒ High production through-put ƒ Used with flux, atmospheres, or vacuum ƒ Slow heating ƒ Pre-placed filler metal ƒ Generalized heating ƒ Thermal cycle control ƒ Applications Retort Furnace z Carbon and stainless steel z Cast iron z Copper z Aluminum

z Titanium [Ref: “Soldering Handbook”, 3rd Ed., AWS] z Ceramics 2-120 Module 2 – Welding and Cutting Processes Brazing and Soldering Processes Immersion (Dip) Soldering

ƒ Drag Soldering z Surface dragging and wetting z Capillary action z Heat transfer z Surface inclination z Dragging time 5 – 15 s

ƒ Wave Soldering z Flux application z Preheat z Soldering z Peel back

[Ref: “Soldering Handbook”, 3rd Ed., AWS] 2-121 Module 2 – Welding and Cutting Processes Brazing and Soldering Processes Other Brazing and Soldering Processes

ƒ Induction ƒ Infrared ƒ Resistance ƒ Laser beam ƒ Hot gas ƒ Microwave ƒ Ultrasonic

[Ref: “Soldering Handbook”, 3rd Ed., AWS] 2-122 Module 2 – Welding and Cutting Processes Brazing and Soldering Joint Design Design Criteria of Brazed and Soldered Joints

ƒ Base material strength ƒ Base material/filler metal metallurgical compatibility ƒ Joint type and geometry ƒ Joint clearance geometry ƒ Fixturing of brazed/soldered parts ƒ Therma l expans ion compa tibility ƒ Filler metal form and placement ƒ Manufacturability ƒ Cost ƒ Safety

2-123 Module 2 – Welding and Cutting Processes Brazing and Soldering Joint Design Joint Design

L

t

ƒ Lap Joints z Best joint efficiency z Controlled by overlap length Š Joint efficiency cam be higher than the weaker member Š L > (3 - 4)t gives the maximum joint efficiency for steel, Cu, Ti, Al z Best manufacturability ƒ Other options include butt and scarf joints 2-124 Module 2 – Welding and Cutting Processes Brazing and Soldering Joint Design Shear Strength of Lap Joints

ƒ Desirable condition ⋅ ⋅τ ≥σ ⋅ ⋅ b L BR UTSBM b t

ƒ Realistic condition ⋅ ⋅τ ≤ σ ⋅ ⋅ b L BR UTS BM b t

τ - Joint Shear strength BR σ BM - Base Metal Tensile Strength

2-125 Module 2 – Welding and Cutting Processes Brazing and Soldering Joint Design Joint Design

ƒ Stresses in brazed and soldered joints z Avoid stress concentration z Apply load to base metal not to joints

2-126 Module 2 – Welding and Cutting Processes Brazing and Soldering Joint Design Joint Design

[Ref: M.M. Schwartz, “Brazing”, 1987] 2-127 Introduction to Cutting Processes

Module 2D Module 2 – Welding and Cutting Processes Cutting Processes Definition of Thermal Cutting Process

ƒ A concentrated heat source melts metal and high speed gas and/or plasma flow removes the melt to form a cut kerf ƒ Some thermal cutting processes z Oxyfuel cutting - OFC z Air carbon arc cutting or gouging – CAC-A z Plasma arc cutting - PAC z Laser beam – LBC

ƒ Waterjet cutting is an alternative cutting technology to the thermal cutting processes

2-129 Module 2 – Welding and Cutting Processes Cutting Processes Oxyfuel Cutting

ƒ Preheat flames produced by combustion of a fuel gas with oxygen z Acetylene, natural gas, propane, etc. ƒ Preheat flames increase metal temperature to allow burning by an oxygen jet ƒ Advantages z Inexpensive z Portable equipment ƒ Disadvantages z Only for oxidizing metals with a low melting point oxide

Courtesy of the AWS Welding Handbook, Volume 1, 9th Edition 2-130 Module 2 – Welding and Cutting Processes Cutting Processes Air Carbon Arc Cutting or Gouging

ƒ Electric arc between carbon electrode melts metal, expelled by pressurized air ƒ Advantages z Portable z Relatively inexpensive ƒ Disadvantages z Debris z Possible carbon deposition

2-131 Module 2 – Welding and Cutting Processes Cutting Processes Plasma Arc Cutting

ƒ Transferred arc plasma jet melts and expels metal from kerf ƒ Advantages z Works for all metals z High speed ƒ Disadvantages z Relativelyyp expensive z Tapered kerf

Courtesy of the AWS Welding Handbook, Volume 1, 9th Edition

2-132 Module 2 – Welding and Cutting Processes Cutting Processes Laser Beam Cutting

ƒ Focused high power laser beam melts material, expelled by assist gas flow z CO2, Nd:YAG, fiber lasers z Air, oxygen, nitrogen, argon assist gases ƒ Advantages z High speed z Narrow kerf ƒ Disadvantages z Expensive

Courtesy of the AWS Welding Handbook, Volume 1, 9th Edition 2-133 Module 2 – Welding and Cutting Processes Cutting Processes Thermal Cutting Materials Effect

ƒ Material heat-affected zone adjacent to kerf z In some materials, heat treatment may be required to restore material properties. ƒ Rapidly-solidified (recast) layer remains on sides of kerf, dross (slag) may be deposited at lower edge of kerf z Dross should be removed prior to welding z Recast layers may require heat treatment or removal by grinding, machining, etc.

Supplementary Paragraph Brief of Variables Essential Essential Nonessential

QW-410 .6 φ Method of Back Gouging x Technique .64 Use of Thermal Processes X ƒ ASME Section IX has a weld procedure variable defining thermal processing of low-alloy quench and tempered steels

2-134 Module 2 – Welding and Cutting Processes Cutting Processes Applicability of Thermal Cutting Processes

Cutting Processes Material OFC PAC CAC-A LBC Carbon steel X X X X

Stainless steel X X X X

Cast ironXXXX

Aluminum X X X

Titanium X X X X

Copper X X X

Refractory materials X X X

2-135 Module 2 – Welding and Cutting Processes Cutting Processes Water Jet Cutting

ƒ High pressure (P=30-60kPSI) water through a small orifice (f = 0.1-0.6mm) erodes material ƒ Abrasive grit usually added to water for metal cutting ƒ Advantages z Non-thermal ƒ Disadvantages z Slow z Expensive

Courtesy of the AWS Welding Handbook, Volume 1, 9th Edition 2-136 Welding Process Applications

Module 2E Module 2 – Welding and Cutting Processes Welding Process Applications Welding Process Applications

2-138 Module 2 – Welding and Cutting Processes Welding Process Applications Narrow Groove

ƒ Often used for thick-wall pipe or nozzle to pipe applications z Weld prep angles as shallow as 1° z Typical GTAW joint preparation and welding setup are shown

10°

3 in. ƒ Processes used in a narrow groove z GTAW z SAW z GMAW 2-139 Module 2 – Welding and Cutting Processes Welding Process Applications Overlay

ƒ Welding is used to deposit weld alloy cladding layers ƒ Provide improved properties of vessel walls, pipes, etc z Corrosion resistance z Wear z Structural integrity ƒ Process parameters are selected to maximize deposition rate, minimize Cross section of dilution of clad metal with base metal tubing with internal weld cladding deposited by GTAW

2-140 Module 2 – Welding and Cutting Processes ASME Section IX – Overlay Procedure Variables ƒ ASME Section IX provides welding procedure variables for overlay welding procedures z The additional welding procedure variables depend on the welding process used to deposit the weld overlay and the application of the overlay (i.e., Hard-Facing or Corrosion-Resistant Overlays) Š Oxyfuel Welding, SMAW, SAW, GMAW, FCAW, GTAW, PAW, ESW and Laser Beam Weldinggy have weld overlay procedure variables Š Many of the variables are duplicates of typical procedure qualification variables Š The variables are usually related to the dilution of the base material or the chemistry of the welding material z Overlay welding procedures require testing to assure the overlay is suitable for the intended purpose

2-141 Module 2 – Welding and Cutting Processes Welding Process Applications ASME Section IX – GTAW Overlay Procedure Variables

Essential Variables Corrosion-Resistant Nonessential Paragraph Hard-Facing Overlay Overlay Variables QW-402 Joint .16 < Finished t < Finished t

QW-403 .20 φ P-No. φ P-No. Base Metals .23 φ T Qualified φ T Qualified .3 φ Wire Size .12 φ Classification .14 ± Filler Metal ± Filler Metal φ Filler Metal Product φ Filler Metal Product QW-404 .23 Form Form Filler Metals .37 φ A-No. QW-405 Position .4 + Position + Position QW-406 Decrease > 100ºF Preheat Decrease > 100ºF Preheat Preheat .4 > Interpass > Interpass 2-142 Module 2 – Welding and Cutting Processes Welding Process Applications ASME Section IX – GTAW Overlay Procedure Variables

Essential Variables Corrosion-Resistant Nonessential Paragraph Hard-Facing Overlay Overlay Variables

QW-407 .6 φ PWHT PWHT .9 φ PWHT

QW-408 .2 φ Single, Mixture, or % φ Single, Mixture, or % Gas .3 φ Flow Rate .4 φ Current or Polarity φ Current or Polarity

QW-409 .12 φ Tungsten Electrode Electrical 1st Layer Heat Input > 1st Layer Heat Input > Characteristics .26 10% 10%

2-143 Module 2 – Welding and Cutting Processes Welding Process Applications ASME Section IX – GTAW Overlay Procedure Variables

Essential Variables Hard-Facing Corrosion-Resistant Nonessential Paragraph Overlay Overlay Variables .1 φ Stringer/weave φ Orifice/Cup or Nozzle .3 Size .5 φ Method of Cleaning .7 φ Oscillation .15 φ Electrode Spacing .25 φ Manual or Automatic .26 ± Peening φ Multiple to Single φ Multiple to Single .38 Layer Layer

QW-410 .50 φ No. of Electrodes φ No. of Electrodes Technique .52 φ Filler Metal Delivery φ Filler Metal Delivery φ Filler Metal Delivery

2-144 Module 2 – Welding and Cutting Processes Welding Process Applications ASME Section IX – Overlay Qualification Requirements

2-145 Module 2 – Welding and Cutting Processes Welding Process Applications ASME Section IX – Overlay Qualification Requirements

2-146 Module 2 – Welding and Cutting Processes Welding Process Applications ASME Section IX – Overlay Qualification Requirements

2-147 Module 2 – Welding and Cutting Processes Welding Process Applications Orbital Welding

ƒ Specialized equipment used for pipe and overlay applications ƒ Can be used with several processes z GTAW z FCAW z GMAW z Hybrid ƒ Can be used in a narrow groove

2-148