The American Welding Society counts more than 90 distinct joining processes, yet most working welders touch only a handful across an entire welder career. That gap between the full catalog and daily practice is where confusion starts.
Processes split into recognizable families: arc welding (stick, MIG, TIG Welding, flux-cored), oxyfuel gas welding, resistance spot and seam welding, solid-state methods like friction and ultrasonic, and high-energy laser and electron beam. Each earns its place by matching a specific base metal, thickness, and production rate.
The practical tension is rarely which process is "best." It's which one fits the code you weld to, the material on your bench, and the equipment budget you can actually justify.
How Welding Processes Are Classified: Fusion, Pressure, and Brazing/soldering
Every joining method used on metal today falls into one of three physical categories, and understanding that split is the fastest way to make sense of a field with dozens of acronyms.
The Three Physical States of a Joint
AWS A3.0, the current 2025 standard that defines welding terminology, sorts welding processes by what happens physically at the joint during coalescence rather than by equipment type.1 Fusion welding melts the base metal into a liquid state, so the joint forms liquid to liquid.2 This is the family that includes SMAW (stick welding), GMAW (MIG welding), FCAW, GTAW (TIG), plasma arc welding, submerged arc welding, oxyfuel gas welding, and the beam processes (laser and electron beam). Solid-state welding, often called pressure welding in shop language, keeps both materials solid throughout and instead uses applied force, sometimes combined with heat, to fuse them at the solid-to-solid interface.2 Resistance welding is conventionally grouped here as well.
Why Brazing and Soldering Don't Count as Welding
Brazing and soldering form a third, separate category: liquid to solid.2 A filler metal melts and flows into the joint, but the base metal itself never reaches its melting point. AWS draws the line at 450°C (840°F) filler liquidus: above that temperature it's brazing, below it's soldering.2 Because the parent metal stays solid, AWS classifies both as allied processes, not true welding, even though the results look similar to an untrained eye.
Numbering and Obsolete Terms
AWS also assigns each process a short letter code (SMAW, GMAW-P, GMAW-S, FCAW-G, FCAW-S, GTAW-P, and so on) that maps to these three families for documentation and welding procedure specifications.3 A3.0 keeps older terms like oxyacetylene welding and carbon arc welding on the books, but flags them as obsolete or seldom used, listed separately so historical documents remain readable without implying they're current shop practice.4
Arc Welding: The Core Processes You'll Use Most
Arc welding still accounts for the overwhelming majority of structural and fabrication work, but the balance inside that family keeps shifting as wire-fed processes take share from stick in the field. Four processes carry nearly all of it, and every credential path you'll encounter is built around some combination of them. All four strike an electric arc between an electrode and the workpiece, melting base metal into a puddle that solidifies into the joint. What separates them is how the puddle gets shielded from atmospheric oxygen and nitrogen, and that single difference drives everything about speed, cleanliness, and how hard the process is to learn.
Stick and Flux-Cored: The Field Processes
- SMAW (shielded metal arc welding), AWS code SMAW, shop name "stick": A flux-coated consumable electrode burns down as you weld, the coating vaporizing into shielding gas and leaving a slag crust you chip off. Equipment is cheap, portable, and tolerant of wind, rust, and paint, which is why it dominates pipeline repair, structural ironwork, and farm work. Downsides: slow, lots of slag cleanup, and you stop to change rods every few inches of weld.
- FCAW flux-cored arc welding: A continuously fed tubular wire with flux in the core. Self-shielded versions (FCAW-S) need no gas bottle and hold up outdoors; gas-shielded versions (FCAW-G) run cleaner and hotter. Deposition rates are the highest of the four, which makes it the default on heavy structural steel, shipyards, and bridge work. Expect slag and expect smoke.
MIG and TIG: The Shop Processes
- GMAW (gas metal arc welding), shop name "MIG": Solid wire fed through a gun with an external shielding gas, usually argon/CO2 blends on steel or straight argon on aluminum. Fast, nearly slag-free, and the easiest of the four to learn, which is why MIG Welding owns auto body, light manufacturing, and most production lines. The tradeoff is wind sensitivity and a tendency to produce pretty-looking welds with cold lap underneath if parameters are wrong.
- GTAW (gas tungsten arc welding), shop name "TIG" or "heliarc": A non-consumable tungsten electrode under argon shielding, with filler rod fed by hand. TIG Welding gives the most control and the cleanest results on thin material, stainless, aluminum, and exotic alloys, and it's standard for aerospace, food-grade stainless, and pipe root passes. It is also the slowest and the most skill-intensive: both hands and one foot are working at once.
Picking Where to Start
Most programs teach stick first because it builds puddle-reading instinct, then MIG for production speed, then TIG for precision. If your target industry is structural, direct your practice hours toward SMAW and FCAW. If it's fabrication or aerospace, GTAW is where your certification money goes.
Plasma, Submerged Arc, and Other Arc Variants
Beyond the core four arc processes lie three specialized variants built for jobs the everyday shop rarely tackles: plasma arc welding (PAW), submerged arc welding (SAW), and electroslag welding (ESW). Each one exists because a specific industry needed more precision, more deposition, or thicker plate than SMAW, MIG welding, TIG, or flux-cored could reasonably deliver.
Plasma Arc Welding (PAW)
PAW is essentially TIG welding's more focused cousin. The arc is constricted through a narrow copper nozzle, producing a high-velocity plasma jet that concentrates heat into a tight column. That focus gives welders exceptional control on thin-gauge stainless, titanium, and exotic alloys, which is why aerospace, medical device, and instrumentation shops rely on it. It also handles keyhole welding on plate up to about half an inch in a single pass. The trade-offs: equipment costs several times more than a TIG rig, torches are delicate, and operators need real training before the process pays off.
Submerged Arc Welding (SAW)
SAW runs a continuously fed electrode under a blanket of granular flux that shields the weld pool, hides the arc, and eliminates most spatter and UV exposure. Deposition rates are enormous, often five to ten times faster than stick, which makes it the go-to process for shipyards, pressure vessel fabricators, structural beam manufacturers, and pipe mills. It is almost always mechanized or fully automated and works best on thick carbon and low-alloy steel in flat or horizontal positions. The catch is that SAW cannot weld out of position, and the flux handling adds a step most small shops will not bother with.
Electroslag Welding (ESW)
ESW joins very thick sections (often two inches and up) in a single vertical pass by melting filler through a molten slag bath. It was once common in heavy structural and shipbuilding work, but concerns about coarse grain structure and reduced toughness pushed most fabricators toward multi-pass SAW or narrow-gap GMAW. ESW still appears in specialized heavy fabrication, though its footprint keeps shrinking.
Welding Equipment and Consumable Costs by Process
Use this table as a starting point, not a quote. Equipment and consumable prices shift by region, order volume, and machine class, so request current figures directly from retailers such as Lincoln Electric, Miller, and Airgas, and from manufacturers or distributors for entry-level versus professional-grade machines. Check BLS.gov for wage and cost benchmarks, use AWS industry cost guides, and review local community college welding program equipment lists as a practical proxy; calculate consumable use per hour or per pound from manufacturer spec sheets before budgeting.
| Process | Equipment Cost | Consumable Cost | Notes |
|---|---|---|---|
| SMAW (stick) | $300 to $800 (basic MIG/stick machine) | $10 to $15 per hour of actual arc time | 1.5 to 3 pounds per hour deposition rate |
| GMAW/MIG | $300 to $800 (basic MIG/stick machine) | $0.80 to $1.40 per pound of weld deposited | 2 to 5 pounds per hour for short-circuit MIG; 5 to 12 pounds per hour for spray MIG |
| FCAW | $300 to $800 (basic MIG/stick machine) | $1.20 to $2.20 per pound of weld deposited | 8 to 25 pounds per hour deposition rate |
| GTAW/TIG | $300 to $800 (basic MIG/stick machine) | $5 to $10 per pound of weld deposited | 0.5 to 2 pounds per hour deposition rate |
| PAW (plasma arc welding) | ₹4,000 supplier unspecified | Not stated | Not stated |
| SAW (submerged arc welding) | ₹4,000 supplier unspecified | Not stated | 12 to 25 pounds per hour; 0.8 to 1.2 pounds of consumable per pound of deposited metal |
| Oxyfuel welding | ₹4,000 supplier unspecified | Not stated | Not stated |
| Resistance spot welding | ₹4,000 supplier unspecified | Not stated | Not stated |
| Friction welding | ₹4,000 supplier unspecified | Not stated | Not stated |
| Ultrasonic welding | ₹4,000 supplier unspecified | Not stated | Not stated |
| Laser welding | Not stated | Not stated | Professional laser welding services $100 to $200+ per hour; equipment price not stated |
| Electron beam welding | ₹4,000 supplier unspecified | Not stated | Not stated |
Material Compatibility and Thickness Ranges by Welding Process
This table summarizes practical material compatibility and thickness ranges for major welding processes, along with the joint types typically used for each. Match the process to the base metal and part thickness before committing to equipment or certification.
| Process | Compatible Materials | Thickness Range | Common Joints |
|---|---|---|---|
| SMAW (stick welding) | Primarily carbon and low-alloy steels; with suitable consumables, stainless steels, cast iron, nickel alloys, copper alloys, and some other ferrous and nonferrous metals | About 1/8 in [3 mm] to several inches with multiple passes for thick plate | Butt, lap, tee, corner, and fillet joints |
| GMAW/MIG | Carbon and low-alloy steels, stainless steels, aluminum and aluminum alloys, magnesium alloys, copper alloys, nickel alloys, and other weldable metals | Thin sheet through heavy plate; short-circuit transfer is commonly limited to 0.25 in [6.4 mm] or less in the cited structural application, while spray and pulsed transfer handle thicker sections | Butt, lap, tee, corner, and fillet joints |
| FCAW | Primarily carbon and low-alloy steels; stainless-steel and nickel-alloy consumables are also available | About 1/8 in [3 mm] through several inches with multiple passes, with especially strong industrial use on medium and thick carbon-steel plate | Butt, lap, tee, corner, and fillet joints |
| GTAW/TIG | Carbon and low-alloy steels, stainless steels, aluminum and aluminum alloys, magnesium alloys, titanium, nickel alloys, copper alloys, and other weldable metals | Very thin sheet and foil through approximately 1/4 in [6 mm] in many manual applications; thicker sections can be welded with multiple passes, but productivity decreases | Butt, lap, tee, corner, edge, and fillet joints |
| PAW (plasma arc welding) | Carbon and stainless steels, aluminum and aluminum alloys, titanium, nickel alloys, copper alloys, and other electrically conductive metals | Thin-sheet and precision applications from approximately 0.040 in [1.0 mm] upward; keyhole plasma is used for thin-to-moderate sections, while non-keyhole plasma is used for thicker plate | Butt, lap, tee, corner, and fillet joints |
| SAW | Primarily carbon and low-alloy steels; stainless steels and nickel alloys can be welded with compatible flux and wire systems | Generally medium-to-heavy plate, approximately 1/4 in [6 mm] to several inches, with multiple-pass welding for very thick sections | Long butt and groove welds, longitudinal seams, circumferential joints, and fillet welds |
| Oxyfuel welding | Carbon steels, low-alloy steels, cast iron, copper and copper alloys, aluminum and aluminum alloys, and some nickel alloys, subject to suitable flux and flame control | Thin sheet through approximately 1/4 in [6 mm] in common manual welding; thicker sections are possible with preheating and multiple passes but are generally less practical | Butt, lap, tee, corner, edge, and fillet joints |
| Resistance welding | Carbon steel, stainless steel, galvanized and coated steels, aluminum alloys, nickel alloys, and other electrically conductive sheet metals | Primarily thin sheet and strip, commonly foil to approximately 1/8 in [3 mm] per sheet for spot welding; heavier total stacks require specialized equipment and procedures | Overlapping lap joints, spot welds, seam welds, projection welds, and butt or upset joints |
| Friction welding | Many weldable metals, including carbon and alloy steels, stainless steels, aluminum alloys, copper alloys, titanium, nickel alloys, and dissimilar-metal combinations | Small-diameter solid sections and tubes through large forgings and shafts; practical thickness is application- and machine-dependent rather than a single universal sheet-to-plate range | Primarily butt joints between rods, tubes, shafts, bars, and rings; friction-stir variants commonly produce butt and lap joints in plate and sheet |
| Ultrasonic welding | Thin ductile metals such as aluminum, copper, nickel, and gold, plus many thermoplastics; especially suitable for similar or compatible dissimilar foils, wires, tabs, and sheets | Foil, wire, and thin sheet; commonly used for very thin components, with capacity governed by horn, anvil, material, and joint design rather than thick-plate welding | Lap joints, foil stacks, wire-to-tab joints, and embedded or bonded thermoplastic joints |
| Laser beam welding | Carbon and alloy steels, stainless steels, aluminum alloys, copper and copper alloys, titanium, nickel alloys, and many other metals; suitable for similar and selected dissimilar-metal joints | Foil to plate; process capability depends strongly on laser power and configuration, with industrial systems welding thin sheet through multi-millimeter and thicker sections, often with multiple passes or hybrid welding | Butt, lap, fillet, edge, and tailored-blank joints |
| Electron beam welding | Almost any metal, including steel, aluminum, copper, titanium, nickel alloys, and many other materials; similar and selected dissimilar-metal combinations are possible | Foil to plate; steel up to 4 in [100 mm], aluminum up to 6 in [150 mm], and copper up to 1 in [25 mm] are identified as weldable in one pass | Primarily precision butt and full-penetration groove joints; lap and other geometries are possible where beam access and fit-up permit |
Related Articles
Gas, Resistance, and Solid-State Welding
Some processes join metal without ever striking an arc, and some barely melt it at all. Oxyfuel, resistance, and solid-state welding sit outside the arc welding family, but they show up constantly in manufacturing, from car bodies to aerospace fittings.
Oxyfuel Gas Welding
Oxyfuel gas welding (OFW), often just called gas welding, burns a mix of oxygen and acetylene to produce a flame hot enough to melt steel. In the history of welding, it was once the default trade process before arc welding took over. Today its niche is narrower but real: thin-gauge sheet metal repair, pipe work in the field where power isn't available, and jewelry or artistic welding. Oxyfuel torches also do double duty for cutting, brazing, and heating, which keeps them in almost every welder's toolbox even if they're not the primary joining method anymore.
Resistance Welding
Resistance welding uses electrical current and mechanical pressure instead of a flame or arc. Current passing through overlapped metal creates heat at the contact point, and squeezing the pieces together forms the joint. Three variants dominate:
- Spot welding: joins overlapping sheets at discrete points, the backbone of automotive body assembly.
- Seam welding: produces a continuous leak-tight joint, used for tanks and containers.
- Projection welding: concentrates current at raised points on one workpiece, common in fastener and bracket attachment.
Solid-State Welding
Solid-state processes join metal without fully melting it. Friction welding spins one part against another under pressure until heat and friction fuse them, common for shafts and fasteners. Friction stir welding drags a rotating tool along a seam, softening and stirring metal together, widely used for aluminum panels in aerospace and shipbuilding. Ultrasonic welding uses high-frequency vibration to bond thin sheets or wires, especially in electronics and battery manufacturing.
These processes rarely make headlines, but they run high-volume production lines every day. Anyone eyeing welding jobs in manufacturing or automation should know these processes exist alongside the arc welding types more commonly taught in shop programs.
High-Energy Welding: Laser and Electron Beam
Laser beam welding (LBW) and electron beam welding (EBW) are the two high-energy-density processes in the welding world. Instead of an arc or a flame, they concentrate an intense beam of photons or electrons onto a spot smaller than a pencil tip, melting metal so fast and so locally that the surrounding material barely heats up. The result is a narrow, deep weld that other processes simply cannot match.
How the Beams Work
Laser welding uses a focused beam of coherent light, typically from a fiber, disk, or CO2 laser source, delivered through optics or a flexible fiber cable. Electron beam welding uses a stream of high-velocity electrons accelerated through a vacuum chamber and steered by magnetic lenses. Both can operate in conduction mode for shallow welds or keyhole mode, where the beam vaporizes a channel through the joint and fuses metal along its walls.
Precision and Depth-to-Width Ratio
These processes routinely achieve depth-to-width ratios of 10:1 or greater, compared to roughly 1:1 for MIG Welding, TIG Welding, and most other arc processes. That means you can weld a joint an inch deep with a bead only a tenth of an inch wide. Heat-affected zones are tiny, distortion is minimal, and thin foils down to a few thousandths of an inch can be joined without burn-through.
Where They Are Used
Aerospace relies on EBW for turbine blades, engine casings, and titanium airframe components. Medical device manufacturers use LBW to seal pacemaker housings, surgical instruments, and implantable titanium parts. Automotive plants deploy laser welding for tailored blanks, transmission gears, and battery tabs in EV production.
Cost and Automation
The tradeoff is capital cost. A production laser cell can run $250,000 to over $1 million; electron beam systems with vacuum chambers often exceed that. Both demand CNC motion control, fixturing, and trained technicians rather than hand-held operation, which is why they live in high-volume or high-value manufacturing rather than field work.
Welding Safety Hazards and Ventilation Requirements by Process
Every welding process carries a mix of physical, electrical, and respiratory hazards. The specific risks shift depending on the arc type, heat source, and consumables, but the Welder Safety framework stays consistent: OSHA's 29 CFR 1910.252 sets the baseline for welding, cutting, and brazing3, and AWS Z49.1 (Safety in Welding, Cutting, and Allied Processes) fills in industry best practice2. OSHA also requires that ventilation systems keep toxic fumes, gases, and dusts below the exposure limits in 29 CFR 1910.10003.
Arc Process Hazards
SMAW, GMAW (MIG Welding), FCAW, and PAW share the same core risk profile: metal fumes, ultraviolet radiation, burns, eye damage, electrical shock, and fire or explosion1. Fume generation runs on the higher side for FCAW and SMAW (flux and coating burn-off), moderate for GMAW, and lower for GTAW (TIG Welding), which uses an inert shield and no flux. GTAW still produces UV and visible radiation plus shock risk from the high-frequency start2. Submerged arc welding is unusual: the granular flux blanket shields most of the arc radiation, so the main concerns are fumes, burns, shock, and fire, though exposed personnel still need radiation protection1.
For all arc processes, provide adequate general ventilation or local exhaust to keep airborne contaminants below OSHA limits1. On stainless, galvanized, or coated stock, or in any confined space, step up to source-capture fume extraction at the torch or hood1.
Non-Arc and High-Energy Processes
Oxyfuel welding and cutting introduces infrared radiation, fire, explosion, and oxygen-enrichment hazards on top of fumes and burns1. Confined-space oxyfuel work requires ventilation sufficient to prevent both toxic accumulation and oxygen deficiency1.
Resistance welding produces fewer fumes in clean steel but adds pinch and crush injuries, sparks, molten metal expulsion, and shock risk2; coated materials (galvanized, painted) can release significant fumes that require local exhaust1.
Laser beam welding demands laser-safety controls for direct and reflected-beam exposure, plus fume and gas extraction2. Electron beam welding operates in vacuum but generates X-radiation that must be contained by chamber shielding, alongside shock, fume, and fire hazards2.
Baseline Practice
Regardless of process, follow the hierarchy: engineering controls (local exhaust, source capture) first, then administrative controls, then respirators. Match hood shade to arc intensity per AWS Z49.12, and never weld on unknown coatings without identifying what will burn off1.
Welding Certifications and Career Paths: Your Roadmap
Welding credentials are not one-size-fits-all. The certification path you choose depends on the code, process, and position you’ll actually weld to.
- AWS Certified Welder (CW)A performance qualification earned by passing a welder test at an AWS Accredited Test Facility. You select the welding process, base metal, joint, and position. It is not granted by school completion alone, and maintenance is required before expiration, commonly every six months.
- AWS Certified Welding Inspector (CWI)An inspection credential, not a welder performance qualification. Candidates meet AWS QC1 education and experience requirements and pass a multi-part exam that includes a vision test. A CWI verifies welds but does not qualify you to weld to a production procedure.
- ASME Section IX welder qualificationA code-based qualification record controlled by your employer or organization. It qualifies you to weld within the ranges of a qualified Welding Procedure Specification (WPS). Changing essential variables such as process or position usually requires requalification.
- API 1104 pipeline weldingA performance qualification used when pipeline projects or owners invoke API 1104. It is specific to pipe material, diameter, wall thickness, joint, and welding process. Project owners may add extra tests or production weld requirements.
- Process-specific and position-specificNo credential automatically covers every process. A SMAW qualification does not transfer to GTAW, GMAW, FCAW, or SAW. Each welding process and position generally needs its own qualification test.
- Inspector career progressionAWS also offers Certified Associate Welding Inspector (CAWI) and Senior Certified Welding Inspector (SCWI) levels, allowing welders to move into inspection and quality-control roles as they gain experience.
Welding Processes by Industry: Where Each Type Excels
Different industries favor specific welding processes because production demands vary. Construction and shipbuilding prioritize deposition rate and thick-material capability, while aerospace favors precision and low heat input. The table below maps common industries to the processes most often used and the practical reasons behind those choices.
| Industry | Most Common Processes | Typical Applications |
|---|---|---|
| Construction and structural steel | Submerged arc welding (SAW), flux-cored arc welding (FCAW), gas metal arc welding (GMAW/MIG) | Structural-steel fabrication and long, thick-material welds; SAW is chosen for high deposition and long weld runs. |
| Automotive | Resistance spot welding, gas metal arc welding (GMAW/MIG) | High-volume vehicle assembly and general automotive fabrication; resistance spot welding handles the high number of joints in production, while GMAW covers general fabrication. |
| Aerospace | Laser welding, gas tungsten arc welding (GTAW/TIG) | Precision aerospace components and safety-critical assemblies; laser welding is valued for precision, low heat input, and high productivity. |
| Pipelines | Mechanized gas metal arc welding (GMAW/MIG), shielded metal arc welding (SMAW/stick) | Pipeline construction and field welding governed by API 1104; mechanized GMAW improves productivity, while SMAW supports field welding and repair. |
| Manufacturing and general fabrication | Gas metal arc welding (GMAW/MIG), flux-cored arc welding (FCAW), gas tungsten arc welding (GTAW/TIG), submerged arc welding (SAW) | General fabrication, heavy fabrication, pressure-vessel production, and automated manufacturing; GMAW for high productivity, FCAW for higher-deposition medium-to-thick work, GTAW for precision and root passes, SAW for long, heavy welds. |
| Shipbuilding and marine | Flux-cored arc welding (FCAW), laser-arc hybrid welding, submerged arc welding (SAW) | Hull, panel-line, shipyard, offshore-platform, and other long-weld applications; FCAW and SAW suit thick materials and high deposition, while laser-based processes improve efficiency and address skilled-labor constraints. |
| Pressure vessels and storage tanks | Submerged arc welding (SAW), gas tungsten arc welding (GTAW/TIG), gas metal arc welding (GMAW/MIG) | Long, thick welds in pressure vessels and storage tanks; SAW is chosen for high deposition and long welds, while GTAW/TIG is used where precise, high-quality welds are required. |
| Energy, wind towers, and heavy fabrication | Submerged arc welding (SAW), flux-cored arc welding (FCAW), shielded metal arc welding (SMAW/stick) | Wind towers, heavy fabrication, large-diameter pipe, and thick plate; SAW is selected for long welds and thick materials, while FCAW and SMAW support heavy structural and field work. |
Choosing the Right Welding Process: A Decision Guide
Start with what you are joining and how thick it is, then narrow by where the work happens and what you can spend. Use the final scenario check to confirm your process choice against real repair or fabrication needs.
Picking a first process and mastering a specialty are two very different problems.
Welding splits into three physical categories: fusion (arc, gas, high-energy beam), pressure (resistance, solid-state), and brazing or soldering. Inside fusion, the arc family carries most day-to-day work, with stick, MIG, flux-cored, and TIG Welding doing the heavy lifting and plasma, submerged arc, and electroslag handling specialized jobs. Matching the process to base metal, thickness, and setting matters more than chasing the newest machine.
If you are starting out, MIG Welding is the easiest to learn on thin steel, and stick is the most forgiving in the field. From there, revisit the safety and certification sections to plan your training path and pick a credential that matches the work you actually want to do.