Welding is a process used in fabrication for thousands of years. Different types of welding help fabricators forge swords, build ships, build furniture, and more. There are many kinds of welding to choose from, each with specific practical applications.
When you start, you will find that some welding types are easier to learn, while other processes can take years to master.
Different types of welding work indoors, while others are best applied outdoors. Read on to learn more about the types of welding and to determine which best suits your needs.
What is Welding?
Welding is a fabrication process whereby two or more parts are fused together by means of heat, pressure or both forming a join as the parts cool. Welding is usually used on metals and thermoplastics but can also be used on wood. The completed welded joint may be referred to as a weldment.
Some materials require the use of specific processes and techniques. A number are considered ‘unweldable,’ a term not usually found in dictionaries but useful and descriptive in engineering.
The parts that are joined are known as a parent material. The material added to help form the join is called filler or consumable. The form of these materials may see them referred to as parent plate or pipe, filler wire, consumable electrode (for arc welding), etc.
Consumables are usually chosen to be similar in composition to the parent material, thus forming a homogenous weld, but there are occasions, such as when welding brittle cast irons, when a filler with a very different composition and, therefore, properties is used. These welds are called heterogeneous.
The completed welded joint may be referred to as a weldment.
Types of Welding Processes
While there are several types of welding processes, such as – Arc welding, Gas welding, Resistance welding, Solid-state welding, Laser beam welding, Electron beam welding, Atomic hydrogen welding, Submerged arc welding, Plasma arc welding, Friction welding, Ultrasonic welding, and Explosive welding, the four main types of welding are:
- Gas Metal Arc Welding (GMAW/MIG)
- Gas Tungsten Arc Welding (GTAW/TIG)
- Shielded Metal Arc Welding (SMAW)
- Flux Cored Arc Welding (FCAW)
In this blog, we’ll detail the specifics assigned to each process and highlight their differences.
#1. Gas Metal Arc Welding (GMAW/MIG).
Also known as Metal Inert Gas or MIG welding, this process uses a thin wire as an electrode. The wire heats up as it is fed through the welding instrument and towards the welding site. Shielding gas must be used to protect the weld from contaminants in the air.
Typically, this comes in the form of carbon dioxide, oxygen, argon, or helium. This method is often used to work on metals such as stainless steel, copper, nickel, carbon steel, aluminum, and more. This one is most popular among all the welding processes across the construction and automotive industries.
GMAW is believed to be an easier welding technique to learn, making it a great area of focus for beginning welders. It also calls for minimal cleanup and offers high welding speeds and better control over thinner materials.
Some downsides associated with this welding process revolve around the costs of getting shielding gas and an inability to weld thicker metals or perform vertical or overhead welding.
#2. Gas Tungsten Arc Welding (GTAW/TIG).
This type of welding process, also known as Tungsten Inert Gas or TIG welding, is commonly used to weld together thin and non-ferrous materials like aluminum, copper, lead, or nickel. It’s commonly applied to bicycle or aircraft manufacturing.
Unlike other types of welding processes, TIG welding uses a non-consumable tungsten electrode to produce the weld. You will still need an external gas supply, usually argon or a mix of argon and helium.
This is considered one of the most difficult welding methods to master and produces the most high-quality welds. Because there is only a tiny area between the arc and the area being welded, it takes enormous precision and skill to complete. Welds born of this method are known to be extremely strong.
#3. Shielded Metal Arc Welding (SMAW).
This type of arc welding process relies on a manual technique using a consumable electrode coated in flux. This method tends to be most popular among home-shop welders. This process is also more informally known as stick welding.
The nickname references the electrode used to weld the metal, which comes in the form of a “stick.” Because SMAW requires minimal equipment, it’s one of the most low-cost processes.
This type of welding does not require shielding gas and can be performed outdoors in the wind or rain. It also works well on dirt and rusty materials. That said, downsides do exist.
Stick welds don’t typically produce the best quality products. They are prone to porosity, cracks, and shallow penetration. In general, stick welds are less durable than other types of welding.
#4. Plasma Arc Welding.
Plasma arc welding is a precision technique and is commonly used in aerospace applications where metal thickness is 0.015 of an inch.
One example of such an application would be on an engine blade or an air seal. Plasma arc welding is very similar in technique to TIG welding, but the electrode is recessed and the ionizing gases inside the arc are used to create heat.
The normal combination of gases is argon for the plasma gas, with argon plus 2 to 5% hydrogen for the shielding gas. Helium can be used for plasma gas but because it is hotter this reduces the current rating of the nozzle.
#5. Electron Beam and Laser Welding.
Electron beam and laser welding are extremely precise, high-energy welding techniques.
Electron beams and lasers can be focused and aimed with the exceptional accuracy required to weld the smallest of implantable medical devices, and yet also deliver the tremendous amounts of power required to weld large spacecraft parts.
Electron beam and laser welding are versatile, powerful, automatable processes. Both can create beautiful welds from a metallurgic and an aesthetic perspective. Both can be cost-effective.
#6. Flux Cored Arc Welding (FCAW).
Similar to MIG welding, FCAW revolves around a continuous wire feed process. There are two separate processes associated with FCAW. One involves the use of shielding gas, while the other relies on self-shielding agents produced when fluxing agents decompose within the wire.
This type of welding is known for being inexpensive and easy to learn. Much like the MIG welding process, it’s a great way for beginning welders to kick off their careers in the field.
It also allows welders to work outdoors (windy conditions won’t affect the weld). The semi-automatic arc provides high welding speed and portability, making it a popular process to employ on construction projects.
#7. Thermite Welding.
Thermite Welding, or exothermic welding, is a welding process that uses molten metal to permanently join the metals to be welded. The process needs thermite – a mixture of metal oxide and aluminum powder.
The process is an exothermic reaction of the thermite composition that heats the metals and fuses them together. An external heat source ignites the thermite and starts the chemical reaction. This type of welding is commonly used to weld cracks in railways and make heavy, strong joints for large pieces of machinery.
#8. Submerged Arc Welding (SAW).
The Submerged Arc Welding process is a type of arc welding. The formation of the arc is made from an electrode, acting as the filler material. The weld zone is entirely covered with a layer of granulated flux, hence the term “submerged” in the name.
This flux is made from carbon and silicate material. The flux generates a gas shield and facilitates electrical conduction when molten. During the welding process, the flux is continuously delivered by a tube attached to a flux hopper.
The entire welding process is mechanized and is buried under the granular flux, so it can’t be seen from the outside.
This type of arc welding process can have a high metal deposition rate of up to 20 kg/hour. It also has a capacity for welding metals with thicknesses up to 100mm. This type of welding is often used in heavy fabrication industries. The aviation industry, shipbuilding, railroads, and bridge-building also use this type of welding.
#9. Gas Welding/Oxyacetylene Welding.
Gas Welding is also known as oxy acetylene-fuel welding or oxy welding for short. This type of welding process is a form of solvent-based fusion welding.
This process involves a handheld torch that pumps out acetylene and oxygen—combining these two burns to form a flame that connects the surface of the two metals using oxygen as the fuel.
The flame produced from combustion is scorching – more than 4500 degrees Fahrenheit. This intense heat is more than enough to weld two metals together.
Welders usually use this welding technique to join thinner metals. These types of metals can be ferrous, non-ferrous metals, alloy steel, carbon steel, etc. Moreover, it has been used in the aircraft and automotive industries.
#10. Electroslag Welding (ESW).
This advanced technique is specifically designed to vertically join thin metal plates edge-to-edge. Unique to ESW, the welding action occurs directly between the edges of the plates rather than being applied externally to a joint.
The process begins by positioning consumable metal guides between the two plates, setting them up for the welding operation. A copper electrode, which doubles as the filler material for the joint, is then introduced through these guides.
The welding arc is initiated by applying an electrical current, and the weld begins at the start of the seam, progressively moving across the designated weld area. This movement is meticulously controlled by a machine, rendering the process fully automated once the plates and guides are set up.
Electroslag Welding is predominantly used for joining low-carbon steel plates that are exceptionally thick. It can also be aptly applied to structural steel, provided certain precautions are considered.
A distinctive feature of ESW is its reliance on slag conduction, which is pivotal in carrying the welding current through the process.
Electroslag Welding (ESW) finds its application in industries such as shipbuilding, power generation, and petrochemical sectors, where it serves as a crucial welding process.
#11. Resistance Welding.
Resistance spot and seam welding (RSW) join two or more welded metal sheets by melting them between the two electrodes as a result of electrical resistance flow. The electrodes introduce electricity into the metal sheets.
However, welded metal sheets have a higher resistance to electricity than electrodes, causing them to melt and fuse. The electrodes also apply pressure before, during, and after the welding process.
Resistance welding is used in the automotive industry, appliance production, aerospace, and general fabrication, where sheet metal must be welded quickly.
#12. Stud Welding.
Stud welding is most commonly applied as an arc welding process where the electric arc is drawn between the stud and the metal surface, causing them to fuse.
The stud gun also applies pressure, plunging the stud into the molten pool. It doesn’t use filler metal, but can require a shielding gas or a ceramic shielding ferrule.
Stud welding is extremely fast. It’s the most productive way to weld a large number of studs to the metal surface. It’s most commonly used for through-deck welding in construction, where shear studs are welded to the steel deck before pouring the concrete.
They are also heavily used in shipbuilding (decks), equipment manufacturing, insulation fastening, cable management, piping supports, and other applications where studs are irreplaceable.
#13. Friction Welding.
Friction welding is an advanced welding process typically used in high-volume production. It involves rapidly moving one part over the surface of another or rotating it, causing friction that melts and fuses the two.
Friction welding and its subgroup friction stir welding are used in industries where weld quality must pass stringent standards. Some applications are aerospace, defense, chemical, nuclear, and similar industries.
Equipment for friction welding can be very expensive and the working process may not be possible for all parts. For example, one part must be symmetrical, and the process must support rotating the part around its symmetry axis.
#14. Cold Welding.
Cold welding uses pressure to form a weld between two metals pressed together. It’s most commonly used for welding wires and applications where electric arc or flame could be hazardous.
It’s limited to welding ductile and face-centered cubic lattice structure metals like aluminum and copper.
#15. Atomic Hydrogen Welding.
Atomic Hydrogen Welding (AHW) is a type of arc welding. It uses an arc between two electrodes made of tungsten with hydrogen gas.
The electric arc between the two electrodes breaks down the hydrogen molecules.
The molecules later recombine and produce a very high amount of heat. This heat facilitates the welding process by fusing the two metals. Nowadays, the GMAW welding process replaced AHW.