What is Welding: Definitions, Different Types

One of the most essential construction-related activities is welding. While there are other processes that can bind materials together, this is the only one that can do so with metals. But most people are unaware that it now goes beyond that definition, even already capable of binding wood and plastic. Also, not a lot of people know that it comes in different types.

The good news if you’re looking at becoming a welder – there’s currently a shortage in the industry for those possessing the skills we’re going to describe below.

We’ll take you on an adventure to start learning some of the basics, and we’ll also include links and references to other articles we have written that you may be interested in.

flux core welding


For many, welding is defined as the process where two metals are joined together using extreme heat. Most people are aware of this definition, but they cannot distinguish it from other similar processes, namely soldering or brazing, and that pressure alone or combined with heat can also melt materials.

Not a lot of people are aware that it is limited to bonding the same kind of material only. This means welding metal to metal is doable, but not metal to steel or any other combination of varying base materials. The same material should be used to ensure a strong final product; not doing so will prevent the two materials from being joined together permanently, which is the goal .

And between welding, soldering, and brazing, welding produces the strongest joints when the practitioner does it correctly.

welder instructing a student

What is it?

In a nutshell, it involves bonding two parent or base materials together that are of the same type using either heat or pressure, or even both. As a result, the two separate parent materials end up becoming one. On the other hand, you can use a plasma cutter when you have a piece of metal that you want to cut – we have also written extensively on how you can find the best one if that is what you are more so interested in.

While it usually involves only the base materials, filler materials can also be added. Metal is added to the weld to strengthen the joint formed, while certain gases are used for shielding to prevent oxidation or contamination that can weaken the joint formed.

High heat from a tool or machine, such as a blowtorch, is used to melt a part or section of the base material where the other one will be attached to. This softens that area or creates a molten pool of material where the material to be joined is attached to. This pool or soften material is set to cool down and once it resolidifies, the two are now joined to form one single material.

Pressure can also be used to bond them together. This pressure alone may be enough to successfully bond the materials involved, or this pressure is used together with the heat generated by the pressure exerted over the base materials that need to be joined together.

welding helmet being put on a student

Different Types

Contrary to what most people think, welding is not just about using a machine to join two metals together. In fact, there are different types present, which are listed below:

Stick Metal Inert Gas Tungsten Inert Gas Flux-Cored Arc
Submerged Electroslag Electrogas Atomic Hydrogen
Carbon Arc Energy Beam Gas Resistance
  • Stick – also known as the Shielded Metal Arc Welding or SMAW, it is named as such because the use of rods or sticks is essential. These rods consist of the filler material that binds the metals and flux that aids in the binding process of the molten metals and at the same time protects them. Stick is considered the most popular in developing countries due to its low cost, despite the weaker bond produced.

Stick is used in a variety of applications and industries, such as construction, aerospace, shipbuilding, marine, petroleum, nuclear, field repair, mining, structural welding, steel fabrication, and manufacturing.

  • Metal Inert Gas or MIG – the second most popular type, the Gas Metal Arc Welding or GMAW technique involves the use of a stick or gun where an electrode current-connected consumable wire passes through. It forms an electric arc that produces enough heat to bond the materials, while at the same time releasing a shielding gas. It has gained popularity due to its ease of use.

MIG is typically used in manufacturing, construction, automotive, and other industrial processes. Check out our section of the various MIG welders that you might have an interest in.

  • Tungsten Inert Gas or TIG – this follows the same process as that of wire or MIG, but it specifically involves the use of a non-consumable electrode containing Tungsten to create the required arc. TIG is now the most popular due to its ability to create a clean weld and high-purity, which results in a superior result.

TIG is commonly used in doing repairs and creating art, as well as in the automotive and aerospace industries.

  • Flux-Cored Arc or FCAW – also similar to MIG, but the wire used is a special tubular type containing flux.

FCAW is best for doing general repairs, as well as in manufacturing, shipbuilding, underwater, and pipeline projects.

  • Submerged Arc or SAW – while it also uses flux, this differs from the flux-cored arc because it occurs under a blanket of loose or granular flux. This results in fewer fumes and ultraviolet light, making it the safest type.

SAW is commonly used in industrial projects, especially in vessel and structural construction.

  • Electroslag – typically used on thick metals that are non-ferrous, it involves melting flux to form a molten slag or pool where an electric arc will pass through. The pool will eventually reach the electrode to extinguish the arc.

Electroslag is also typically used for industrial purposes, such as castings, vessels, structures, ships, machinery, and pressure vessels.

  • Electrogas– shares the same process as electroslag, but the electric arc present is deliberately left alone. Also, the arc is known to be positioned vertically and allows the process to occur in a single pass.

Electrogas is best for the construction of storage tanks, blast and chemical furnaces, vertical vessels, bridges, and ships.

  • Atomic Hydrogen or AHW – slowly becoming obsolete, this type involves using two metal tungsten electrodes in an atmosphere containing hydrogen. This will cause the hydrogen to break apart and recombine, generating the heat that is needed.

AHW is suitable for any application where rapid processing is a must.

  • Carbon Arc ‘or CAW – known as the first type of arc welding, the CAW technique uses a carbon electrode that is non-consumable to heat the metals together, eventually bonding them. It is also becoming obsolete.

CAW is known for being suitable for use with copper, repairing cast iron parts with bronze, galvanized steel, and for thinner materials.

  • Energy Beam or EBW – involves placing the parent materials in a total vacuum and shooting a beam of electrons to those materials at high velocity. The electrons fired are converted to heat that is needed to melt them and bond them together. It has two specific types available: electron beam and laser beam welding

EBW is used for a wide variety of industries, namely aerospace, research, defense, medical, power generation, electronics, oil and gas, and automotive.

  • Gas – best known as oxyacetylene or oxyfuel welding, fuel gases are mixed with pure oxygen to adjust the temperature of the flame of a torch used for the bonding process. It is considered as one of the oldest types of the trade.

It is normally used in manufacturing, as well as in the aircraft and automotive industries.

  • Resistance – force is applied to both ends of the metal to be joined and an electric current is applied nearby to create the extreme heat required’. Various techniques of resistance ‘nclude seam, spot, flash, upset, butt, and projection welding.

It is best for industrial, aerospace, and automotive applications.

Among the different types used, arc is the most widely used in various industries. Arc is a broad category that covers stick, MIG, TIG, flux-cored arc, submerged arc, electroslag, electrogas, atomic hydrogen , and carbon arc welding and is used in a wide variety of industries. All these require electricity to generate the arc required for the bonding process.

Not a lot of people know that it can also be done underwater, but only for specific types. Hyperbaric is a specialized option that can be done via either wet or dry welding. Wet welding often uses the stick type, with the bubbles produced by the flux acting as a shield to prevent electrocution of the craftsman. On the other hand, dry welding involves creating a hyperbaric chamber surrounding the area before following the chosen type.

welder welding inside a building


Aside from choosing what type to use, craftsmen also concern themselves with choosing among the processes available to determine which one is most suitable for their project. Which process to choose mainly depends on the type of joint, whether edge, T, butt, corner, or lap, and the material to be joined together.picture of a welder

Cold pressure  Explosive  Friction  Inertial 
Induction  Percussion  Ultrasonic   

The processes available are broadly categorized into two: fusion and pressure.

Fusion – the process many are most familiar with since it involves heat to bond materials together. The edges of the parent material are heated so that when they cool down and harden, they are already joined together. Using filler material and inert gases are optional, and no pressure is needed to bond them together. The different types mentioned above fall under fusion.

It should be noted that fusion requires at least one of the parent materials to have a solid-state solubility, as this determines their weldability. If the parent material is non-soluble in the solid state, it will require a soluble material for the process to be possible.

On the other hand, the pressure techniques involves the use of external pressure to the joints to be joined. Producing these joints are done through either solid state welding, which involves adding pressure at temperatures below the melting points, or fusion state that requires doing so at above melting point temperatures.

Unlike fusion, pressure requires that the joints or ends of the material are free of contaminants, particularly oxides and films that are non-metallic in nature. These joints should be completely clean to ensure that the joint made between the materials is the strongest possible.

Welder at construction site

Pressure welding is normally used when the materials involved are known for being ductile or whose ductility increases as the temperature also increases. Some examples are:

  • Cold pressure – joins materials, specifically for electric components, wires, and sheets, without requiring heat to do so.
  • Explosive – necessary if the parent materials are dissimilar metals whose joints require welding, such as for cladding. This solid-state process involves using explosives to bond materials together. These explosives cause one of the materials to accelerate toward the other and weld them together.
  • Friction – two metals are rubbed together and the friction between them generates the heat needed. This is also suitable for dissimilar metals, but it can also be used for similar ones
  • Inertial – similar to the friction technique, but it involves rotating one of the materials to the other, with the latter remaining stationary. This is ideal for alloys with high strength
  • Induction – mostly used for pipes and tubes, it involves using an induction coil that electromagnetically produces the heat required. The tube or pipes involved pass through the coil at high speeds, which causes heating on its edges and are squeezed together to form a seam that joins them together.
  • Percussion – involves using quick electrical discharges to form an arc that has a high temperature. This discharge causes pressure to be applied to the materials involved, bonding them together. This is also suitable for joining dissimilar metals
  • Ultrasonic – vibrations are produced through sound waves at high frequency, and these cause the materials to bond together. This is normally used for thin sheets and plastics.

Choosing the right piece of equipment

Welder working inside

It’s a wild world out there, and you may very well be in the very early stages of choosing the piece of equipment that will in fact get done what it is you are hoping to have it do, why we want to start preparing you for the process.

While you may not necessarily have an initial need for an engine driven welder, there is a chance that you may want one of those one day – if you are just getting started, it may be hard to justify going out and spending $4,000 to $6,000, which is the typical range that these machines fall in, if you haven’t already figured out the ins and outs of the business that you are trying to build.

There’s no denying that these types of machinery do have a time and a place, and that there are some craftsmen out there that are making extremely impressive metal work with some of these machines, but it’s like saying that you need to go out and spend in excess of $10,000 to buy a portable sawmill just because you have a couple of trees in the backyard that you are cutting down, or like saying that you need to buy a wide belt sander just because you found a piece of wood in your backyard that you want to smooth out a little bit.

Is that really what you want to do, or would you rather that you find the piece of equipment that may be appropriate to your level and start off by buying that. If you do that, you will make sure that you don’t go out and ruin a very expensive piece of equipment at the time that you are just learning how to do the craft!

While we have a bunch of different equipment available on our platform, we also encourage you to take a look at other platforms and see what your needs may be, and where you feel confident starting out the process – you may already have a price point in mind that you don’t want to go over, and if that is the case, we can definitely recommend a piece of equipment that works for that price point, too!

If you are getting more serious about your welding adventures and you have already figured out some of the features that would be important to you, we can recommend an appropriate machine.

However, if you are really trying to stay cost conscious, we would still not recommend that you simply go online and find the cheapest piece of equipment, as it will simply be a nightmare to work with, so in those instances, we would almost always rather encourage you to just buy something that has been mildly used before.

Welder in the middle of a weld

What to start looking for

As you have already seen, if you have made it this far down the article, is, that there are so many different processes that you can choose from, with each one of them having their own individual advantages and disadvantages to consider. You will need to figure out which one you will want to get started with, as it’s really quite likely that the first piece of equipment you buy will be tailored to only providing that one type of process.

If you are just getting started, and you want something that is relatively easy to learn without having a big need that all the welds have to be absolutely perfect, and of the highest quality, we’d probably recommend that you get started with MIG, although if you are slightly more ambitious and already know that you are wanting to take this craft more seriously, we’d recommend you skip that step and go straight to TIG.


You will also need to have an idea as to the type of work that you will be needing to do, as that will both guide the welding equipment you are looking for, as well as the process you should be doing. There are better and worse processes for each type, with the auto body repair kind of work being the thinnest types of metal you will likely be working on, whereas work on hunting stands and utility trailers requiring significantly more power.

Be sure that you are looking for equipment that can actually provide you with the level of power to weld the types of surfaces that you are looking to work on. You don’t want to have great aspirations for doing some really serious work, while you are left with a piece of equipment that does not have any realistic chance of providing you with that power that you so desperately need. The thicker the type of surface you’ll be working with, the higher the current will also need to be.

Be sure to check out the duty cycle of the machine that you are looking at, which is also often an indication as to whether you are currently looking at a cheap piece of machinery, or whether you are actually looking at a respectable piece of machinery. If you are looking to occasionally do a little bit of body repair work, you probably don’t need an extravagant machine with a high duty cycle, but you will still want something that won’t drive you crazy to use.

worker at construction site

Final note

Did this article on the topic help give you a better understanding of the process, or do you still have questions regarding the various types? On the topic of metal work, we have also written an article on how you get started using a plasma cutter, and if you aren’t entirely sure where to continue on from here, we also recommend a battle between the two most common types with our MIG vs TIG article.

Here at Atlantic Aspiration we’re on a mission to provide users with the best possible content when it comes to professional services like welding, woodworking and more, why we are continuously expanding our offering of articles. If you’re curious to learn more, you can also dive into our article on the best plasma cutters, where we take a closer look at some of the popular options on the market, and if you save this platform somewhere convenient and visit again next month, we’ll probably also have posted a bunch of new articles that might interest you, like this one on low-maintenance dwarf shrubs

Leave a Comment

Your email address will not be published. Required fields are marked *