Compendium

Welding Processes — Family Index

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Welding Processes — Family Index

Cross-reference of the metal-joining processes recognized by the American Welding Society (AWS) and ISO 4063, with AWS letter codes, ISO numeric codes, typical filler-metal specifications (AWS A5.x), and process-selection guidance. Companion to [[Engineering/joining-welding]] (overview) and [[Engineering/Tier3/joining-taxonomy]] (whole-tree taxonomy including mechanical fastening and adhesive bonding).

1. At a glance — AWS process family tree

AWS A3.0 (Standard Welding Terms & Definitions) and ISO 4063 (Numerical representation of welding processes) divide all welding into the following high-level groups. Every weld procedure specification (WPS) references a process from this list.

  • Arc welding (AW) — heat from electric arc between electrode (consumable or non-consumable) and work.
    • SMAW — shielded-metal-arc (“stick”), AWS code SMAW, ISO 111
    • GMAW — gas-metal-arc (“MIG/MAG”), AWS code GMAW, ISO 131 (inert gas) / 135 (active gas)
    • FCAW — flux-cored-arc, ISO 136 (gas-shielded) / 114 (self-shielded)
    • GTAW — gas-tungsten-arc (“TIG”), AWS code GTAW, ISO 141
    • SAW — submerged-arc, AWS code SAW, ISO 12
    • PAW — plasma-arc, AWS code PAW, ISO 15
  • Solid-state welding (SSW) — no melting; bond forms below solidus by pressure + plastic flow ± frictional heat.
    • FRW — friction (rotary), ISO 42
    • FSW — friction-stir, ISO 43
    • LFW — linear friction (no ISO number; AWS recognized)
    • USW — ultrasonic, ISO 41
    • CW — cold welding (pressure only), ISO 48
    • DFW — diffusion welding, ISO 45
    • EXW — explosion welding, ISO 441
    • FOW — forge welding, ISO 43 (historically)
  • High-energy-density (HEDW) — focused-beam keyhole melting.
    • LBW — laser-beam, ISO 52
    • EBW — electron-beam, ISO 51
  • Resistance welding (RW) — Joule heating at faying surfaces under electrode force.
    • RSW — resistance spot, ISO 21
    • RSEW — resistance seam, ISO 22
    • PW — projection, ISO 23
    • FW — flash, ISO 24
    • UW — upset, ISO 25
  • Oxyfuel-gas welding (OFW) — chemical combustion flame.
    • OAW — oxy-acetylene, ISO 311
    • OHW — oxy-hydrogen, ISO 313
  • Other fusion — thermite (TW, ISO 71), electroslag (ESW, ISO 72), electrogas (EGW, ISO 73), stud welding (SW, ISO 78).
  • Brazing & soldering — separate AWS C3 committee (B = braze, S = solder). Filler melts; base metal does not. Included here in §17 because procedurally adjacent.

2. AWS / ISO 4063 process-code crosswalk

AWS letterISO 4063Process
SMAW111Shielded-metal-arc (stick)
GMAW131Metal-inert-gas (MIG, Ar/He shield)
GMAW135Metal-active-gas (MAG, CO₂ or Ar+CO₂)
GMAW138Metal-cored arc (composite solid wire)
FCAW-G136Flux-cored gas-shielded
FCAW-S114Flux-cored self-shielded
GTAW141Gas-tungsten-arc (TIG)
PAW15Plasma-arc
SAW12Submerged-arc
RSW21Resistance spot
RSEW22Resistance seam
PW23Projection
FW24Flash butt
LBW52Laser-beam
EBW51Electron-beam
FSW43Friction-stir
FRW42Friction (rotary)
USW41Ultrasonic
ESW72Electroslag
OAW311Oxy-acetylene
TW71Thermite
SW78Arc stud

3. Shielded-Metal-Arc Welding (SMAW / “stick”)

Consumable flux-coated electrode struck against work, constant-current (drooping) power source. Slag covers solidifying pool, must be chipped between passes. Equipment is portable and tolerant of wind/contamination — dominant in field structural, pipeline tie-ins, repair.

Filler specs (AWS A5 series):

  • A5.1 — carbon-steel covered electrodes. E6010 (cellulosic, all-position, deep penetration, pipeline root), E6011 (AC version of 6010), E6013 (rutile, easy-arc, sheet), E7014 (iron-powder rutile), E7016 (low-hydrogen basic), E7018 (low-hydrogen iron-powder, structural workhorse), E7024 (high-deposition iron-powder, flat/horizontal only).
  • A5.5 — low-alloy covered. E7018-A1 (½Mo), E8018-B2 (1¼Cr-½Mo for P11 piping), E9018-B3 (2¼Cr-1Mo for P22), E8018-C3 (Ni for low-temp), E11018-M (military 110 ksi).
  • A5.4 — stainless covered. E308L-16 (304L base), E309L-16 (dissimilar joints, clad overlay first layer), E316L-16 (316L), E347-16 (Nb-stabilized), E2209-16 (duplex 2205).
  • A5.11 — nickel covered. ENiCrFe-3 (Inconel 182, for 600/625/X-750).
  • A5.15 — cast-iron. ENi-CI, ENiFe-CI for repair of Class 30/40 gray iron.

Coating types: cellulosic (E6010/11 — high H₂, deep penetration), rutile (E6013, E7014 — easy arc, low penetration), basic/low-hydrogen (E7018, E7016 — tough, requires oven storage at 120-150 °C to keep diffusible H < 8 mL/100g), iron-powder (high deposition).

Typical use: pipeline X70 girth welds (downhill cellulosic root + low-H fill/cap), structural steel buildings (A992), pressure-vessel field welds, cast-iron repair.

4. Gas-Metal-Arc Welding (GMAW / MIG / MAG)

Continuous solid-wire electrode through gun, external shielding gas. Constant-voltage power supply. Higher deposition than SMAW, no slag (no chipping), excellent for production.

Shielding gas selection:

  • 100% Ar — Al, Mg, Cu, Ti (DCEP).
  • Ar + 1-2% O₂ or Ar + 2-5% CO₂ — stainless spray transfer.
  • Ar + 5-25% CO₂ (“C25” = Ar+25%CO₂) — carbon steel spray/pulsed.
  • 100% CO₂ — carbon-steel short-circuit, deep penetration, more spatter, cheaper.
  • Ar + He (25-75% He) — Al thick section, higher heat input.

Filler specs:

  • A5.18 — carbon-steel solid wire. ER70S-3 (general), ER70S-6 (highest Mn/Si — workhorse, runs over mill scale), ER70S-2 (triple-deox for rusty plate).
  • A5.28 — low-alloy solid wire. ER80S-D2 (Mo), ER80S-Ni1, ER110S-G.
  • A5.9 — stainless solid wire. ER308LSi, ER309LSi (transition layer on cladding), ER316LSi, ER347Si, ER2209 (duplex). “Si” = silicon-enhanced for improved bead wetting.
  • A5.10 — Al wire. ER4043 (Al-Si, general 6061), ER4047 (high-Si braze-like), ER5356 (Al-Mg, high-strength 5xxx/6xxx, marine), ER5183, ER5556.
  • A5.14 — Ni wire. ERNiCrMo-3 (Inconel 625), ERNiCrMo-4 (Hastelloy C-276), ERNiFeCr-2 (alloy 718), ERNiCr-3 (alloy 82 for nuclear pressure-vessel clad).
  • A5.16 — Ti wire. ERTi-1 to ERTi-5 (CP grades + Ti-6Al-4V).

Metal-transfer modes:

  • Short-circuit (GMAW-S, “short arc”) — 17-22 V, < 220 A. Wire dips into pool ~50-200 Hz. Thin material (0.6-3 mm), out-of-position, gap-bridging. Cold — risk of lack-of-fusion in thick steel.
  • Globular — transition regime, large irregular droplets, much spatter. Avoided.
  • Spray — > 24 V on Ar-rich shield (>80% Ar). Fine droplets propelled axially. Flat/horizontal only (fluid pool). High deposition, smooth bead. Production fillet welding.
  • Pulsed (GMAW-P) — modern inverter pulses between background (no transfer) and peak (one drop per pulse). All-position spray-like, low heat, controllable. Aluminum (Lincoln Power Wave, Miller Axcess, Fronius TPS/i, ESAB Aristo).
  • Controlled short-circuit — Lincoln STT (Surface Tension Transfer), Miller RMD (Regulated Metal Deposition), Fronius CMT (Cold Metal Transfer — reciprocating wire). Used for open-root pipe and Al sheet (§16).

5. Flux-Cored Arc Welding (FCAW)

Tubular wire with flux/alloy core. Higher deposition than GMAW, deeper penetration, better tolerance of mill scale and primer.

  • FCAW-G (gas-shielded) — external CO₂ or Ar+CO₂ shield. Flux generates slag + deoxidizers. Used for thick structural steel, shipbuilding, mining equipment.
  • FCAW-S (self-shielded) — core generates all shielding gas + slag, no external gas. Used in field where wind would blow gas away (bridge erection, ironwork, storage tanks). Lincoln NR-211, NR-232, Hobart Fabshield.

Filler specs:

  • A5.20 — carbon steel. E71T-1 (gas, rutile, all-position, structural workhorse), E70T-1 (gas, flat/horizontal high-deposition), E71T-8 (self-shielded, low-H, structural — AISC seismic prequalified), E71T-11 (self-shielded, general — sheet metal).
  • A5.29 — low-alloy. E81T1-Ni1 (low-temp impact), E91T1-K2.
  • A5.22 — stainless flux-cored. E308LT1-1, E309LT1-1.
  • A5.36 — unified spec (2016+) combining A5.20/A5.29 carbon + low-alloy under one designation system with optional supplemental codes.

6. Gas-Tungsten-Arc Welding (GTAW / TIG / WIG)

Non-consumable tungsten electrode in Ar (or Ar+He) gas; filler added separately as cut rod or cold-wire feed. Constant-current power. Cleanest, most precise process — no spatter, low heat input, excellent control. Slow.

Electrode types (AWS A5.12 / EN ISO 6848):

  • EWP (pure W, green band) — AC for aluminum/magnesium (ball tip from melted end).
  • EWTh-2 (2% thoria, red band) — DC for steel; legacy; radioactive (ThO₂), being phased out.
  • EWLa-1.5 / EWLa-2 (lanthanated, gold / blue band) — modern replacement for thoriated; non-radioactive, runs AC and DC.
  • EWCe-2 (cerium, orange band) — low-current TIG, orbital.
  • EWZr-1 (zirconium, brown band) — AC aluminum, retains balled shape.

Polarity:

  • DCEN (DC-) / “straight polarity” — 70 % heat in workpiece, narrow penetration. Steel, stainless, Ni, Ti, Cu.
  • DCEP (DC+) — 70 % heat in electrode (overheats W). Rarely used except thin Al with helium and short bursts. Provides cleaning.
  • AC (sine or square-wave inverter, balanced or EP/EN biased) — Al/Mg only. EN half cycle = penetration; EP half cycle = cathodic cleaning of refractory Al₂O₃ oxide.

Shielding: 100% Ar standard; Ar+He for Al thick section (hotter); Ar+H₂ (1-5%) for austenitic stainless (faster, cleaner — never on ferritic or martensitic — H embrittlement).

Variants: orbital GTAW (Polysoude, AMI, Magnatech) for sanitary tube welding (semiconductor fab gas distribution, pharmaceutical 316L, dairy) — auto-rotating head, programmable pulse, no filler (“autogenous”) on thin wall. Hot-wire TIG — resistive preheat of filler wire — high deposition for clad overlay.

Typical use: aerospace Ti-6Al-4V (with Ar trailing shield + back-purge), bicycle frames, exotic alloys, root passes of pressure-vessel pipe, sanitary stainless, jewelry.

7. Submerged-Arc Welding (SAW)

Bare consumable wire under a blanket of granular flux that melts to form a protective slag. Arc is buried — no visible UV/IR — operator-friendly. Extremely high deposition (5-30 kg/h on a tandem-wire head, up to 100 kg/h on triple-wire ESAB / Lincoln tractor systems).

Filler specs:

  • A5.17 — carbon-steel wire-flux combinations. Designation example: F7A2-EM12K = 70 ksi tensile, as-welded, 20 ft-lb @ 0 °F, EM12K wire on neutral-fused flux. Wires: EL8, EM12K, EH14. Fluxes: Lincoln 761/780/860, ESAB OK Flux 10.71 / 10.81, Hobart Cougar.
  • A5.23 — low-alloy SAW. F8A4-ECM2-M2 (Cr-Mo).
  • A5.25 — electroslag (ESW) wire-flux pair.

Typical use: longitudinal seams of large-diameter pipe (DSAW = double-submerged-arc, X70/X80 line pipe), pressure-vessel longitudinal welds (ASME Section VIII), shipbuilding flat-panel butt welds, wind-tower can welds, beam fabrication.

Flux can be fused (glassy, neutral, recyclable) or bonded/agglomerated (alloyed, picks up moisture). Flux recovery via vacuum hose feeds it back into hopper.

8. Plasma-Arc Welding (PAW)

GTAW with the arc constricted through a water-cooled copper orifice. Plasma gas (Ar) + shielding gas (Ar or Ar+H₂). Three flavors:

  • Microplasma — 0.1-15 A — foil welding (50-500 µm), jewelry, bellows, thermocouples.
  • Medium-current “soft” plasma — 15-100 A — sheet metal aerospace.
  • Keyhole PAW — 100-400 A, single-pass full-penetration of 3-10 mm stainless/steel/Ti in one shot — used for stainless tube longitudinal seam mills (linear at 1-3 m/min), aerospace Ti pressure vessel.

Arc is stiffer than TIG (narrow column, less torch-to-work-distance sensitivity). Slower than laser but cheaper.

9. Resistance welding

Joule heat (I²R) at the faying interface; electrode force forges the molten “nugget.” No filler. Power: AC line, MFDC (medium-frequency 1 kHz DC inverter), or capacitor-discharge.

  • RSW (spot) — auto body BIW workhorse. 3-15 kA at 6-12 V for 50-300 ms with 1-5 kN electrode force. ISO 18278/18594 for Al; AWS D8.1 / D8.9 for steel automotive. Cu-Cr-Zr electrodes. Hot-stamped boron steel (22MnB5) and Al 6xxx have driven RSW to MFDC + adaptive control (Bosch, ARO, NIMAK). New: friction-stir spot alternative (§10) for Al, DeltaSpot with consumable Cu ribbon for Al-steel dissimilar.
  • RSEW (seam) — wheel electrodes, overlapping nuggets → leak-tight. Sealed steel fuel tanks (legacy), automotive exhaust mufflers, can ends. Mash seam = lap with crushed lap.
  • PW (projection) — embossed bump or wire concentrates current. Cross-wire (refrigerator shelves), nut welding, bolt welding to BIW.
  • FW (flash butt) — two faces brought together under current, arcing “flashes” off oxides, then forged. Rail-track butt joints — AWS D15.2, EN 14587. Tubing mills (HF induction seam-weld of API line pipe is electrically similar but uses HF current rather than contact).
  • HFRW / HFIW — high-frequency (450 kHz) resistance/induction for ERW pipe mills (API 5L PSL2). Replaced flash-butt for pipe.

10. Friction welding (solid-state)

No melting — bond from plastic flow under heat from friction + forging force. Excellent for dissimilar metals, no porosity/HAZ-cracking issues, no filler/shielding.

  • FRW (rotary friction) — one part spins, the other is held; faces brought together; spin stops; forge force applied. Variants: continuous-drive (motor stays on through forge) and inertia friction (flywheel — Manufacturing Technology Inc., Thompson Friction Welding). Used for drive shafts, valves (Inconel head on stainless stem), drill-stem subs, aero engine compressor shafts.
  • LFW (linear friction welding) — reciprocating linear motion (~25-100 Hz, 1-3 mm amplitude); used for non-axisymmetric joints. Bladed disks (“blisks”) in jet engines — Rolls-Royce Trent, GE GE9X, Pratt & Whitney F119 — replaced firtree-root dovetail blades with LFW-joined integral blade-disk monolith. Equipment: TWI / MTI / KUKA.
  • FSW (friction-stir welding) — invented Wayne Thomas, TWI 1991 (GB 2,306,366). A non-consumable rotating tool (shoulder + pin) plunges into the joint and traverses; material plasticizes around the pin and is forged behind. Solid-state — no melting, no porosity, no solidification cracking. Tool: H13, MP-159, or PCBN (for steel/Ti) — MegaStir (now MELD) is canonical PCBN supplier.
    • Use cases: aluminum aerospace tank welds (SpaceX Falcon 9/Heavy LOX & RP-1 tanks, ULA Atlas V/Delta IV, NASA SLS core stage, Boeing Delta IV upper-stage), 787 spar (some sections), F-22 aft skin, automotive Al BIW (Honda NSX subframe), shipboard panel (Marine Aluminium / Hydro), railcar Al extrusions (Hitachi Shinkansen, Bombardier).
    • Variants: FSSW (friction-stir spot) — Mazda RX-8 / Toyota Prius Al hood; Refill FSSW (no keyhole — Helmholtz HZG, GKSS); bobbin-tool FSW (no backing anvil — full-penetration both sides); stationary-shoulder FSW for Ti (TWI); per FSW for additive (MELD Manufacturing).
  • USW (ultrasonic) — 20-40 kHz transverse oscillation under clamping force. Cold (< 1/3 Tmelt). Battery tab welding (Li-ion pouch tabs to bus bar — Branson, Schunk Sonosystems, Telsonic), wire-harness splices (Schunk), Al-to-Cu electronics. Power 1-10 kW.
  • CW (cold welding) — pure pressure, no heat. Al-Al cable splices, Cu-Cu. Pure plastic flow extrudes oxide.
  • EXW (explosion welding) — sheet of plastic explosive over flyer plate accelerates it onto baseplate at km/s; oxide-free wave-shaped interface. Clad plate (Ti-on-steel chemical-tank cladding, Al-on-steel transition joints for ship superstructures — DMC Clad / Nobelclad).
  • DFW (diffusion welding) — sustained pressure + temperature in vacuum or inert; atoms interdiffuse across interface. Aerospace Ti structures, Sup3D-printed-part joining.

11. Laser-Beam Welding (LBW)

Focused photon beam (typ. 100-500 µm spot) — power densities > 10⁶ W/cm² produce a keyhole vapor cavity that traps the beam and gives deep penetration with low heat input.

Laser sources:

  • Fiber laser (Yb-doped fused silica) — IPG Photonics (dominant), nLIGHT, Trumpf TruFiber, Coherent. 1070 nm, wall-plug efficiency 30-40 %, beam delivered through fiber. Power 1-50 kW. Dominant today.
  • Disk laser (Yb:YAG) — Trumpf TruDisk. Same wavelength.
  • Diode laser (direct) — broad spot, conduction-mode brazing/cladding.
  • CO₂ laser (10.6 µm) — older; cannot use silica fiber (Cu mirror delivery); declining. Some auto-body installs still operate.

Modes: conduction (low power density, shallow weld, smooth bead — battery tab, e-mobility hairpin) vs keyhole (deep, narrow, high aspect ratio — auto body BIW seam, ship deck).

Use: automotive tailored blanks, EV hairpin stator winding (Cu, 3-6 kW fiber), Li-ion battery cell-to-busbar (1-2 kW pulsed green/IR for Cu), aircraft skin-to-stringer (Airbus A380 fuselage panels, A320neo), shipbuilding plate.

12. Electron-Beam Welding (EBW)

Stream of electrons accelerated through 30-200 kV in a vacuum chamber (HV 10⁻⁴ mbar, MV 10⁻² mbar, NVEB = non-vacuum at 1 atm with degraded penetration). Deep keyhole — 50-200 mm in steel single pass. ~99 % efficient at converting input electrical to absorbed beam (after gun losses); very narrow HAZ.

Vendors: PTR/Hamilton, Sciaky (also EB additive — EBAM), Pro-Beam, Cambridge Vacuum Engineering.

Use: aero engine disks (rotor LP turbine, IP compressor — Rolls-Royce, GE), nuclear pressure-vessel longitudinal/circumferential welds (Kyushu Electric, Areva), gear-to-shaft (transmission), bimetal saw bands (HSS tooth-band onto spring-steel back), Ti-6-4 spaceframes.

13. Oxyfuel welding (OFW)

Chemical flame (oxy-acetylene 3,200 °C, oxy-hydrogen 2,800 °C, oxy-propane 2,500 °C). Flame settings: neutral (1:1 O₂:C₂H₂, general), carburizing/reducing (excess fuel — surfacing cast iron, hardfacing Stellite), oxidizing (excess O₂ — brass).

Largely displaced by GMAW/GTAW for production welding; survives for:

  • Light-gauge sheet repair (auto body restoration).
  • Brazing torches (oxy-acetylene for BAg fillers on HVAC Cu).
  • Cutting (OFC, ISO 81) — still dominant for structural-steel demolition and shipbreaking.

14. Thermite welding (TW, “exothermic welding”)

Goldschmidt 1893. Filler is a powdered mixture of aluminum + iron oxide (Fe₂O₃ or Fe₃O₄): Reaction is self-sustaining at ~2,500 °C; molten Fe runs into a graphite/sand mold around the joint; slag (Al₂O₃) floats. No external power.

Use:

  • Rail-track field joints — Pandrol (formerly Railtech Boutet), Goldschmidt-Thermit. Continuous welded rail (CWR) in-track joints worldwide.
  • Cadweld® / Erico — electrical grounding bonds — Cu-thermite to bond Cu cable to rebar, structural steel, ground rods. Substation and lightning-protection ground grids.

15. Hybrid laser-arc welding (HLAW)

Coaxial / tandem laser + GMAW. Laser provides deep keyhole penetration (single-pass full-penetration 8-15 mm steel); GMAW arc provides filler addition, gap bridging, and improved fit-up tolerance. Travel speeds 1-3 m/min on shipbuilding plate. Pioneered by Meyer Werft (cruise-ship panel lines) and ESAB Hybrio. Use also in heavy automotive (Audi A8 spaceframe nodes), Lincoln HyperFill.

16. Cold-Metal-Transfer (CMT) and other controlled-short-circuit GMAW

Modern inverter-controlled processes that mechanically retract the wire (Fronius CMT) or current-shape (Lincoln STT, Miller RMD) the short-circuit transfer to eliminate spatter and reduce heat input ~30 % vs conventional short-arc.

  • Fronius CMT — wire reciprocates at 70-130 Hz; pulls drop off after short. Used for thin Al (down to 0.3 mm), galvanized-steel auto body (Zn boils — CMT suppresses), and CMT braze (Al-Si filler on Zn-coated steel for roof-to-body joints in Audi, Mercedes).
  • Lincoln STT (Surface Tension Transfer) — controls current during the ball-detach. Pipeline open-root replacement for SMAW cellulosic E6010 (especially on TMCP X80).
  • Miller RMD (Regulated Metal Deposition) — sanitary stainless open root, pipe.
  • ESAB SAT (Swift Arc Transfer), OTC Lincoln STAH.

Used also for WAAM (wire-arc additive manufacturing — large-scale Ti/Al/steel near-net-shape parts; Norsk Titanium, Cranfield/WAAM3D).

17. Brazing (in scope for joining-process selection)

Filler melts (> 450 °C, < base-metal solidus) and capillaries into a close-fit joint (typ. 0.05-0.15 mm). Base metal does not melt. Different AWS committee (C3) but appears in every WPS selection matrix because it competes with welding for thin/dissimilar/leak-tight joints.

Heating methods:

  • Torch brazing — oxy-acetylene/oxy-propane; HVAC Cu tubing (BCuP); plumbing.
  • Induction — RF coil; automotive fittings, carbide tool tipping, sensor housings. Eldec / Ambrell / Inductoheat.
  • Furnace — controlled atmosphere (H₂, N₂/H₂ “dissociated ammonia”, or vacuum). Brazed-Cu copper-water heat-exchangers in HVAC, EGR coolers.
  • Vacuum brazing — 10⁻⁵ mbar; oxide-free; Ni-base BNi fillers, aerospace honeycomb panels, fluid plates for fuel-cell stacks, additively-manufactured part joining (Premier Aviation, IPSEN, ALD).
  • Dip brazing — molten flux salt bath; Al automotive heat exchangers (legacy — now CAB / NOCOLOK flux furnace).

Filler metals (AWS A5.8):

  • BAg-x — silver-copper-zinc-cadmium (BAg-1, -1a, -2) or Cd-free (BAg-7, -24). Tube-to-fitting in instrumentation, HVAC service valves. Working T 600-800 °C.
  • BCuP-x — Cu-P (BCuP-2, -3) self-fluxing on copper. Refrigeration tubing.
  • BCu-1 — pure Cu — furnace-brazed steel hydraulic fittings.
  • BNi-x — Ni-Cr-(Si-B-P). High-temperature service (jet-engine fuel manifold, turbine static parts). Vacuum/H₂ furnace, 1,050-1,200 °C.
  • BAlSi-x — Al-Si (BAlSi-4 = 4047) — Al auto-radiator (CAB process).
  • BAu-x — Au-Cu/Au-Ni — electronics, medical implants, high-vacuum.

18. Comparison table

ProcessEnergy modeThickness rangeDeposition ratePositionShieldingTypical use
SMAW (111)Arc, CC1.5-100 mm1-3 kg/hAllCoatingPipeline, structural field, repair
GMAW short-arc (135)Arc, CV0.6-3 mm1-3 kg/hAllGasSheet, thin, gap bridging
GMAW spray (135)Arc, CV3-25 mm4-9 kg/hFlat/horizGas (Ar)Production fillet/groove
GMAW pulsedArc, CV1-15 mm3-7 kg/hAllGasAll-position production
FCAW-G (136)Arc, CV3-50 mm3-12 kg/hAllGas + fluxStructural, shipbuilding
FCAW-S (114)Arc, CV3-25 mm2-6 kg/hAllFlux onlyField structural (windy)
GTAW (141)Arc, CC0.1-10 mm0.5-2 kg/hAllGas (Ar)Aerospace, Ti, root passes
SAW (12)Arc, CC/CV5-200 mm5-30 kg/hFlatGranular fluxPipe-mill, vessel, ship plate
PAW (15)Arc, CC0.05-10 mm0.5-2 kg/hAllGasStainless tube, foil, aerospace
RSW (21)Resistance0.5-3 mm/siden/a (spot)n/aNoneAuto BIW
RSEW (22)Resistance0.4-2 mmn/an/aNoneLeak-tight cans, exhaust
FW (24)Resistance5-200 mm rodn/aButtNoneRail joints
LBW (52)Photon beam0.1-25 mmvariesAllGas / noneAuto BIW, EV stator, aero
EBW (51)Electron beam1-200 mmvariesFlat (vac)VacuumAero engine disk, nuclear PV
FSW (43)Solid-state0.5-75 mm Aln/aMostly flatNoneAerospace Al tank, rail car
FSSWSolid-state1-3 mm Aln/a (spot)n/aNoneAl auto BIW
LFWSolid-staten/a (forge)n/an/aNoneJet-engine blisk
USW (41)Solid-state< 1 mm foil/wiren/an/aNoneBattery tabs, harness
ESW (72)Slag resistive25-500 mm15-40 kg/hVerticalFluxHeavy plate, ship rudder
OAW (311)Combustion< 6 mm< 1 kg/hAllFlameRepair, brazing torches
TW (71)Chemicaln/a (cast)n/an/aMoldRail tracks, grounding
Hybrid laser-arcPhoton + arc4-25 mm4-12 kg/hAllGasShipbuilding, automotive
CMT (135 var.)Arc, CV0.3-4 mm1-4 kg/hAllGasAl sheet, Zn-steel braze
Vacuum brazingFurnacen/an/an/aVacuumAero heat-exchangers

19. Filler-metal specifications (AWS A5.x summary)

SpecProcess(es)Metal familyExample designation
A5.1SMAWCarbon steelE7018-H4R
A5.4SMAWStainlessE316L-16
A5.5SMAWLow-alloyE8018-B2
A5.7GTAW/GMAWCu alloyERCuSi-A
A5.8BrazingAllBAg-1, BNi-2
A5.9GTAW/GMAW/SAWStainless wireER308LSi
A5.10GTAW/GMAWAlER5356, ER4043
A5.11SMAWNi-base coveredENiCrFe-3
A5.12GTAWW electrodeEWLa-1.5
A5.13SMAW surfacing—ECoCr-A (Stellite)
A5.14GTAW/GMAWNi-base bareERNiCrMo-3 (625)
A5.16GTAW/GMAWTiERTi-5
A5.17SAWCarbon steel wire-fluxF7A2-EM12K
A5.18GMAWCarbon steelER70S-6
A5.20FCAWCarbon steelE71T-1
A5.22FCAWStainlessE309LT1-1
A5.23SAWLow-alloyF8A4-ECM2-M2
A5.28GMAW/GTAWLow-alloyER80S-D2
A5.29FCAWLow-alloyE81T1-Ni1
A5.30AllInserts/consumable insertsIN308
A5.36GMAW/FCAWUnified (replaces A5.20/A5.29/A5.28)E71T1-C1A2-CS1

20. Process selection heuristics

  • Thin (< 1 mm) Al sheet → GTAW pulsed AC or Fronius CMT (lowest distortion).
  • Thick (50-200 mm) steel single pass → SAW (flat), EBW (vacuum), or hybrid laser-GMAW (open).
  • Field structural high-strength steel → SMAW E7018 (low-H, AISC seismic) or FCAW-G E71T-1 / FCAW-S E71T-8.
  • Sanitary stainless 316L tube (semicon, pharma, dairy) → orbital GTAW (Polysoude / AMI / Magnatech), autogenous with Ar back-purge.
  • Aerospace Ti-6Al-4V → GTAW with Ar trail + back-purge (clean field), EBW (vacuum, deep), or LBW (closed cell).
  • Auto-body steel BIW → RSW; for Al BIW → RSW (MFDC, Cu-Cr-Zr electrodes) or FSSW or laser-stitch.
  • Pipeline X70/X80 root → SMAW cellulosic E6010 (manual) or GMAW STT/RMD (mechanized).
  • Pipeline fill/cap → SMAW E8010-G or FCAW-G or mechanized GMAW pulsed.
  • Ship hull / panel line → FCAW-G E71T-1 or hybrid laser-GMAW (Meyer Werft, STX).
  • Rail-track joint → Thermite (Pandrol) in field; flash-butt in shop / rail-mounted welder.
  • Spacecraft Al alloy tanks (2xxx/5xxx) → FSW (SpaceX Falcon, ULA Atlas/Delta, NASA SLS, Blue Origin New Glenn).
  • Jet-engine blisk → LFW (Rolls-Royce, GE, P&W).
  • Aero-engine compressor rotor disks → EBW (Rolls-Royce Trent welded rotor stack).
  • Battery cell tabs → USW (Cu/Al tabs to bus bar) or green laser (Trumpf 515 nm for Cu).
  • EV hairpin stator winding → fiber LBW.
  • Heat-exchanger Cu manifold → torch brazing BCuP-2 (or furnace BCu-1).
  • Cast-iron repair → SMAW with ENi-CI / ENiFe-CI nickel electrodes, low heat, peening between passes.
  • Dissimilar Al-to-Steel auto roof → CMT braze with Al-Si filler on Zn-coated steel.

21. Codes & qualification

Procedure / welder qualification (WPS / PQR / WPQ):

  • AWS D1.1 — structural steel (buildings, bridges).
  • AWS D1.2 — structural aluminum.
  • AWS D1.3 — structural sheet steel.
  • AWS D1.4 — reinforcing steel (rebar).
  • AWS D1.5 — bridge welding code (AASHTO).
  • AWS D1.6 — structural stainless.
  • AWS D1.8 — seismic supplement to D1.1 (moment frames).
  • AWS D14.x — industrial / mill equipment.
  • AWS D15.1 / D15.2 — railroad, rail-flash-butt.
  • AWS D17.1 / D17.2 — fusion / resistance welding for aerospace.
  • AWS D18.x — sanitary / hygienic stainless tube.
  • ASME BPVC Section IX — pressure-equipment WPS/PQR/WPQ (the global de-facto pressure-vessel and piping standard, referenced by Section VIII Div 1/2 vessels, B31.1/B31.3 piping, etc.).
  • ISO 15614 — WPS qualification (multiple parts by process: -1 arc, -7 surfacing, -11 EB/LB, -12 spot/seam/projection, -13 flash, -14 hybrid laser-arc).
  • ISO 9606 — welder performance qualification (-1 steels, -2 Al, -3 Cu, -4 Ni, -5 Ti).
  • EN 1090 — execution of steel & aluminum structures (Europe, includes welder & WPS requirements + factory production control).

NDT methods for welds (see separate Tier3 note for NDT): RT (radiographic), UT (ultrasonic, incl. PAUT and ToFD), PT (penetrant), MT (magnetic-particle), ET (eddy current), VT (visual).

22. Cross-references

  • [[Engineering/joining-welding]] — survey-level Tier 2 note (parent).
  • [[Engineering/Tier3/joining-taxonomy]] — overall joining decision tree (welding + brazing + adhesive + mechanical).
  • [[Engineering/Tier3/steel-grades]] — base-metal weldability (carbon-equivalent, CET, preheat, HAZ hardness).
  • [[Engineering/Tier3/aluminum-alloys]] — 1xxx-7xxx weldability, ER4043/ER5356 selection.
  • [[Engineering/Tier3/stainless-steels]] — 304L/316L/duplex 2205/super-duplex weld procedure constraints, Schaeffler/DeLong/WRC-92 diagrams.
  • [[Engineering/Tier3/titanium-alloys]] — α/α+β/β weldability and shielding requirements.
  • [[Engineering/Tier3/copper-alloys]] — brass/bronze/Cu-Ni weldability.
  • [[Engineering/Tier3/fasteners-taxonomy]] — non-welding alternative when applicable.

23. Citations & primary references

  • AWS Welding Handbook (9th ed., multi-volume) — Volume 1 (Welding Science & Technology), Volumes 2-3 (Processes), Volume 4 (Materials & Applications), Volume 5 (Materials & Applications).
  • Lincoln Electric, Procedure Handbook of Arc Welding (14th ed., 2000) — process selection and PQR practice.
  • AWS A3.0 — Standard Welding Terms and Definitions.
  • ISO 4063 — Welding and allied processes — Nomenclature of processes and reference numbers.
  • AWS A5.x — filler-metal specifications (see §19 table).
  • AWS D1.x / D14.x / D17.x — welding codes.
  • ASME BPVC Section IX — Welding, Brazing, and Fusing Qualifications.
  • ISO 15614 / 9606 — WPS / welder qualification.
  • Kou, S., Welding Metallurgy, 3rd ed., Wiley, 2020 — HAZ, solidification cracking, dissimilar metals.
  • Lippold, J. C., Welding Metallurgy and Weldability, Wiley, 2014.
  • Messler, R. W., Principles of Welding, Wiley, 1999.
  • Thomas, W. M. et al., GB Patent 9125978.8 (1991) — Friction-stir welding (TWI, Cambridge).
  • Mishra, R. S. and Ma, Z. Y., Friction Stir Welding and Processing, Materials Science and Engineering R 50 (2005) — canonical FSW review.
  • API 1104 — Welding of Pipelines and Related Facilities (transmission pipelines).
  • EN ISO 6848 — Tungsten electrodes for inert-gas-shielded arc welding.

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