The main types of welding are stick (SMAW), MIG (GMAW), flux-cored (FCAW), TIG (GTAW), submerged arc (SAW), oxy-fuel gas welding and resistance spot welding. The first five use an electric arc to melt the metal, and they do most of the work on steel structures, from beams and columns to trailers and handrails.
Each process differs in how it makes heat, how it shields the molten metal from the air, how fast it lays down weld, and how much skill it takes. This guide explains each one in plain terms, compares them in a table, and covers which processes are used on structural steel and why.
How Welding Processes Are Grouped
OSHA’s fact sheet Controlling Hazardous Fume and Gases during Welding (checked October 2026) sorts welding into two groups: fusion welding, which uses heat alone, and pressure welding, which uses heat and pressure. It splits fusion welding into electric arc, gas and thermit welding, and notes that electric arc welding is the most widely used.
Every arc process works the same basic way. An arc between an electrode and the workpiece melts the base metal and usually a filler metal, forming a weld pool that cools into a solid joint. The molten metal has to be protected from oxygen and nitrogen in the air, or the weld turns porous and brittle. That protection comes from a shielding gas, a flux, or both, and how each process supplies it is the biggest difference between them.
Arc Welding Processes
1. Stick welding (SMAW)
Shielded metal arc welding uses a short rod electrode coated in flux. As the rod burns off, the coating gives off gas that shields the arc and leaves slag over the bead. The OSHA fact sheet describes the electrode as providing both the flux and the filler metal. The equipment is simple and portable, there is no gas bottle, and it copes with wind and less-than-clean steel, which is why it stays common for field repairs and site work. The downsides are slow deposition, frequent rod changes and slag to chip off between passes.
2. MIG welding (GMAW)
Gas metal arc welding feeds a solid wire continuously through a gun while a shielding gas flows around it from a bottle. It is fast, makes clean welds with little cleanup and is one of the easier processes to learn, which makes it a shop favorite for steel fabrication, sheet metal and general repair. Because the gas can be blown away, it is less suited to windy outdoor work. Our MIG vs TIG welding comparison goes into the differences in more detail.
3. Flux-cored welding (FCAW)
Flux-cored arc welding looks like MIG but uses a tubular wire with flux inside it. Self-shielded wires make their own shielding from the flux, so they work outdoors without gas; gas-shielded wires add a bottle for better weld quality in the shop. FCAW lays down metal quickly and penetrates well on thicker steel, so it is widely used in structural fabrication and erection. It leaves slag like stick welding and, per OSHA, produces the most fume of the common arc processes.
4. TIG welding (GTAW)
Gas tungsten arc welding uses a tungsten electrode that does not melt, with filler rod added by hand and an inert gas shield, usually argon. It gives the most control and the neatest welds, and it handles thin material, stainless steel and aluminum well. It is also the slowest arc process and needs the most skill. It is used where appearance or precision matters more than speed, such as on stainless work covered in our welding stainless steel guide.
5. Submerged arc welding (SAW)
In submerged arc welding, a wire is fed into a joint buried under a layer of granular flux, so the arc is hidden. It is almost always mechanized, running on a tractor or a fixed rig. It deposits weld metal very quickly with deep penetration, which makes it a fit for long, straight welds on thick plate, such as built-up girders, plate columns and heavy pipe. It is limited to flat and horizontal positions because the loose flux has to stay in place.
Other Types of Welding
6. Oxy-fuel gas welding
Gas welding melts the joint with a flame, usually from oxygen and acetylene. OSHA notes it is a common method for welding iron, steel, cast iron and copper. It needs no electricity, and the same torch set can cut, braze and heat. It is slow and puts a lot of heat into the part, so it is now used more for repair, brazing and cutting than for structural welding.
7. Resistance spot welding
Spot welding is a pressure process. Two copper electrodes clamp overlapping sheets and pass a high current through them; the resistance heats a small spot until it fuses. There is no filler or shielding. It is fast and easy to automate, so it is used for sheet metal in car bodies, appliances and enclosures, but not for structural shapes.
Types of Welding Compared
| Process | Electrode or heat source | Shielding | Outdoors in wind | Skill to learn | Typical uses |
|---|---|---|---|---|---|
| Stick (SMAW) | Flux-coated rod, consumed | Flux coating | Good | Moderate | Field work, repairs, structural steel |
| MIG (GMAW) | Solid wire, consumed | Gas from a bottle | Poor | Easier | Shop fabrication, sheet, general repair |
| Flux-cored (FCAW) | Tubular wire, consumed | Flux core, with or without gas | Good (self-shielded) | Moderate | Structural fabrication and erection, heavy equipment |
| TIG (GTAW) | Tungsten, not consumed | Inert gas | Poor | Hardest | Thin metal, stainless, aluminum, precision work |
| Submerged arc (SAW) | Wire, consumed | Granular flux | Shop process | Machine operated | Thick plate, long straight welds |
| Oxy-fuel | Gas flame | Flame envelope | Fair | Moderate | Repair, brazing, cutting |
| Resistance spot | Electrical resistance and pressure | None | Shop process | Machine operated | Sheet metal assemblies |
Which Welding Processes Are Used on Structural Steel?
In the fabrication shop, steel beams, columns and connection plates are usually welded with FCAW or GMAW for speed, with submerged arc for long welds on built-up members. In the field, where wind would blow away a gas shield, erectors lean on stick welding and self-shielded flux-cored wire. Our structural steel fabrication article walks through where welding fits in the shop process.
Structural welding in the US is normally done to the AWS D1.1 Structural Welding Code, Steel (AWS page checked October 2026), which covers welding procedures, welder qualification and inspection. The weld size, type and length are shown on drawings with standard symbols; our weld symbols chart explains how to read them. Coated steel needs extra care: see welding galvanized steel for why the zinc has to be dealt with first.
The process does not decide whether a weld is strong enough. Weld size and type for any structural connection have to be designed by a licensed structural engineer and made by a qualified welder following an approved procedure.
Safety Across All Types of Welding
All welding produces fume, and arc welding also gives off intense ultraviolet light. The OSHA fact sheet ranks the arc processes by fume output, from most to least: flux-cored, stick, MIG and TIG. It lists the metals that can be in welding fume, including manganese, chromium and nickel, and notes that exposure depends on the process, the base and filler metals, and whether the work is outdoors or in an enclosed space. Local exhaust ventilation, eye and skin protection and fire watch are standard. OSHA’s welding, cutting and brazing page links to the standards for general industry, maritime and construction.
Types of Welding FAQ
What are the 4 main types of welding?
The four most common are stick (SMAW), MIG (GMAW), flux-cored (FCAW) and TIG (GTAW). All four are arc welding processes.
What is the easiest type of welding to learn?
MIG is usually the easiest to start with, because the wire feeds automatically and there is no slag. TIG is generally the hardest, because both hands and often a foot pedal are in use at once.
What type of welding is best for steel beams?
Shops commonly use flux-cored or MIG, and submerged arc for long welds on heavy members. On site, stick and self-shielded flux-cored are preferred because they are not upset by wind. The procedure must meet AWS D1.1 or whatever code the project specifies.
Which type of welding is strongest?
No process is strongest in general. A correctly made weld from any of the arc processes, with the right filler metal and size, can match or exceed the strength of the steel it joins. Strength depends on design, procedure and workmanship.
Can you weld outdoors with MIG?
It is possible with wind screens, but drafts can blow the shielding gas away and cause porous welds. For outdoor work, stick or self-shielded flux-cored wire is usually more reliable.
Reference information only, not engineering advice. Disclaimer.