What is Fusion Welding?

Fusion welding is a method that makes use of heat to combine or fuse two or more materials into a melting point by heating them. The method may involve the use of filler material, or it may not.

Outside pressure application is not needed for fusion welding processes, with the exception of resistance welding, where significant contact pressure is necessary for the sound joining during welding. Here is more on what is fusion welding.

What is welding?

Before we start to discuss ‘what is fusion welding’, it is important to quickly understand welding and its two main types. Welding can be described as a manufacturing process through which two or more identical or different materials can be securely joined by the forming of coalescences with or without filler component applications, heat, or outside pressure.

Welding processes may be loosely divided into two categories – fusion welding and solid-state welding– based on the absence or presence of base material fuses. If fading surfaces of parent components melt down together with filler material to form weld beads, it is called fusion welding.

At the other end, if no melting happens throughout welding, then it is considered solid-state welding. Parent components, however, can be warmed to extreme temperatures in solid-state welding (but lower than its boiling point).

What is fusion welding?

Fusion welding methods include the welding methods in which faying parent surfaces, as well as filler material, liquefy during welding for the creation of welded beads. Therefore heat is often related to these processes.

Outside pressure application is not needed for these processes, except for a resistance welding group where there is a need to sustain significant contact pressure throughout welding to ensure a solid joint. It may or may not be added to filler material.

What are the different fusion welding processes?

When discussing fusion welding, the different fusion welding processes are the most critical things to understand. Fusion welding processes may be categorized by the heat source, e.g. high energy, electrical resistance, gas, and electric arc.

Based on this, the following are the different fusion welding processes:

Arc welding processes

Arc-welding is the most common method of fusion welding. Arc welding lives up to the hype; it uses an electric arc to connect two or more parts.

With electric arcs reaching up to six thousand degrees Fahrenheit, this method of fusion welding is extremely competent at fusing even the hardest metals.

In addition, underwater arc welding can be carried out, making it a perfect solution for offshore ventures. The most common fusion welding processes being used today, arch welding processes include the following.

Shielded metal arc welding (SMAW)

Often referred to as stick welding, flux shielded arc welding, or manual arc welding (MMAW), SMAW is useful for welding in all places of the ferrous and non-ferrous components.

MIG and MAG welding

Short for Metal Inert Gas Welding and Metal Active Gas Welding, MIG and MAG Welding are often referred to as gas metal arc welding (GMAW). Arc welding processes that are increasingly common today, MIG and MAG, are welding processes where an electrical arc occurs between the workpiece and perishable wire electrode, which leads to melting and binding.

In the case of MIG welding, both use a shielding gas to secure the weld against airborne chemicals or oxidation.

Tungsten inert gas welding

TIG welding is an arc method that produces the arc between the base plate and the electrode using a tungsten electrode that is not consumable. This inert shielding gas is used to shield against oxidation or other pollution in the atmosphere.

This method can be used viscerally on lean parts, but for heavier components, it will involve inserting a tube, rod, or consumable.

Plasma arc welding

This method utilizes an electric arc produced between a torch nozzle and an electrode. The gas (typically argon) within the area is ionized by the arc, producing what is called a spark.

It is then pushed via a fine bore copper nozzle, which inhibits the arc and guides it to the workpiece, enabling the spark arc to be isolated from the shielding gas (typically created from a combination of hydrogen and argon).

Submerged arc welding (SAW)

A commonly utilized arc welding method, SAW utilizes an actively fed usable electrode and a fusible flux blanket which, when molten, becomes permeable and creates a current path between the electrode and the workpiece. The plasma, while removing ultraviolet radiation and gases, also stops staining and fires.

Flux colored arc welding

Created as an alternate to SMAW, this method utilizes a regularly fed perishable electrode with a flux and a steady voltage or power supply with consistent voltage. This process may also often use a shielding gas to ensure safety from the atmosphere using only the flux.

Gas welding processes

The following is the most commonly used gas welding process today:

Oxy-fuel welding

Often referred to as gas welding and oxyacetylene welding, oxy-fuel welding is a process that utilizes a blowpipe or torch that can be held in hand with a combination of acetylene and oxygen that burns to form a flare. Oxyfuel welding, which is a form of solvent-based fusion welding, requires the utilization of a flame to melt and connect surfaces, using oxygen as the fuel source.

Naturally, fire requires oxygen, which is the foundation on which oxyfuel welding operates. The fire is fueled by oxygen to produce a hot flame greater than four thousand five-hundred degrees Fahrenheit.

Oxyfuel welding generally uses a mixture of combustible gas and oxygen to produce a hot flame for materials to connect together.

Resistance welding processes

The following are the most commonly used resistance welding processes today:

Resistance spot welding

This simple bonding method produces heat across two electrodes, depending on the thickness of the workpiece and the properties of the material. The welding voltage is confined to a small location, as the workpieces are fastened together concurrently.

Resistance seam welding

This form of spot welding creates a sequence of persistent joint alternating nuggets by swapping traditional spot welding electrodes with disks that shift as the workpieces are rotated in between them.

High energy welding processes

The following are the main types of high energy welding processes.

Electronic beam welding (EBW)

This method of welding is carried out under atmospheric conditions, with the use of a wave of high-velocity electrons to fuse the workpieces as the electrons produce heat as they enter the material. Welts are mostly thin and deep.

Laser beam welding (LBW)

Frequently utilized in large-volume applications, LBW makes use of a laser beam to ensure a focused energy source of high precision rates that can be utilized to connect polymers and metal. Often referred to as laser welding, this includes the use of light energy for heat generation.

The laser welding rig basically shoots out dissipated light on the surfaces. The surfaces get a little warmer with every blast.

These connect together as the artifacts melt.

There you have it—the different fusion welding processes. Using the information above, you can determine which fusion welding process is the best for your application.

Additionally, you can thoroughly understand how the different fusion welding processes work by referring to the information provided above.

The advantages and disadvantages of fusion welding processes

Fusion welding processes come with their fair share of pros and cons. The following are the advantages and disadvantages of fusion welding processes:

The advantages of fusion welding processes

The following are the main advantages of fusion welding processes:

  • It’s easy to weld two or more components at a single stage.
  • It can be easily added to filler material, so you can fill a big gap
  • The design of the joint and preparation of edges are not important, as these variables mostly impact possible penetration
  • There is no need to apply outside pressure – therefore, the primary element shape doesn’t matter (an appropriate structure is needed to create pressure evenly)

Disadvantages of fusion welding processes

The following are the main disadvantages associated with fusion welding processes:

  • Binding different metals via fusion welding is a difficult job, particularly if the metals have significantly different points of melting and thermal expansion coefficients
  • The method is linked with degradation and the production of remnant stress as it requires fusion and solidification
  • Extreme heating also significantly affects the microstructures of parent materials
  • The soldered parts include a measurable heat-affected zone (HAZ), which is often seen as the vulnerable component of the welded assembly


In this article, we discussed the different fusion welding processes as well as the main advantages and disadvantages of these welding processes. With this information, you can decide whether using fusion welding processes for your application is a good idea or not and also which fusion welding process you should use for your application.