Welding Terminology Guide

This section of our site contains information, definitions and explanations of terms very common in the welding industry. If any information on this site has been a bit confusing, this page will probably help you.

Welding is the sculptural or fabrication process where materials, usually thermoplastics and metals, are joined through fusion. This process is distinct and is quite different from the lower-temperature metal joining techniques like soldering and brazing which do not melt the base metal. After melting the base material, an extra filling material is added to the welded joints to create a weld pool (a pool of molten material), which, once it has cooled down, forms a joint that is as strong as the base metal material.

Now there are different methods that are used when it comes to welding. It is therefore important that you first understand some of the common welding methods before looking at the basic welding terminologies. 

SMAW or Shielded Metal Arc Welding

Also referred to as stick welding, this welding approach employs the use of an electrode with flux (which is the material that protects the puddle) around it. The electrode holder then holds this electrode in place as it slowly melts the material away. The importance of the slag is to protect the welding puddle from atmospheric contaminants.

GTAW or Gas Tungsten Arc Welding

Also called TIG or Tungsten, Inert Gas, this method employs the use of a non-consumable tungsten electrode to create the weld. The area being welded is protected from atmospheric contaminants by an inert shielding gas like Helium or Argon.

GMAW or Gas Metal Arc Welding

Also known as MIG or metal inert gas, this method uses a wire-feeding gun that feeds a wire at a speed that can be adjusted and flows an argon based shielding gas or a mixture of carbon dioxide and argon over the weld puddle to shield it from contaminations.

FCAW or Flux-Cored Arc Welding

This method is almost similar to MIG welding, the only difference is that it uses a special tube-like wire that’s filled with flux. Depending on the filler used, this wire can be used with or without the shielding gas.

SAW or Submerged Arc Welding

This method uses a consumable electrode that is automatically fed and a blanket of granular and fusible flux to weld. The molten material and the arc zone are both protected from contaminants by being submerged in this flux blanket.

ESW or Electro Slag Welding

This is a highly productive, single-pass welding process designed to weld thicker materials; that is materials that are between 1 inch or 25mm and 12 inches or 300mm in or close to a vertical position.

Arc Blow

This basically refers to when the arc is going everywhere you do not want it to go. However, this only happens in DC mode and especially when welding up into corners. It is believed that the effect is in somehow caused by magnetism.

Arc Cutting

This is the process where one cuts through steel using the arc’s force. While arc cutting does not make very pretty cuts, it gets the job done when you do not have a torch at hand. Arc cutting can be done using a 6011 or a 6010 rod with the welding machine turned up to very hot or warp 10.


This refers to any element (metal) that is added to another metal to improve its properties.

Backup Strip

The backup strip is a section or strip of steel that butts up to an open space between 2 pieces of steel. A 6010 welding rod can be used in open butt-welding while the 7018 cannot and will require a backing strip to provide a better surface where the electrode to weld to.

Build-Up Weld

This is where there one builds up the surface of any steel part such as a sprockets teeth or the bucket on the front-end of a loader. In this option, the welder simply builds up a component that serves as a replacement of a part that either broke off or got worn out. Often, build-up welds are normally done or created using hard surface electrodes.


This is where a fillet weld bead slumps inwardly from the face of the Root to the Root itself.

Consumable Insert

In this instance, the filler rod or wire stands in a gap; you then weld it on to the base metal along with the rod.

Critical Temperature

Critical temperature refers to when the base metal transitions from solid state to liquid state as you heat it up. It’s at this crucial point that things go from being solid matter, to melting, then to molten.


The cylinder in welding is where the oxygen and acetylene are stored. Cylinders are also used for shielding the gases used in TIG and MIG welding processes. Cylinders come in different sizes and shapes.

Depth of Fusion

This refers to how deep a filler material penetrates into the base metal from its surface.

Edge Preparation

Before welding a plate or pipe edge, it is important that the edge is prepared to ensure that the weld is sound. Edge preparation basically entails the torch cutting, machine grinding, filing, or beveling of the edge.

Flash Burn

Flash burns refer to the burn from the radiations produced from the UV rays emitted by the welding arc. The burns caused by these UV rays are very much similar to those experienced after getting sunburned and blister the cornea. Often, one doesn’t realize it until a couple of hours later when they start feeling as though their eyes are being rubbed with hot sand.

Flow Meter

The flow meter basically works at reducing the pressure in the shielding gas bottle as it can soar to up to 2400 lbs. per in.

Heat Affected Zone

When welding, even the area surrounding the part you are working on gets affected by the heat. As it cools down, temperatures will fall at different rate throughout the material. This heating and cooling will significantly affect the properties of the material. Materials that are considerably affected by heat will usually crack if not managed well.


Refers to the lowest temperature that a metal or steel becomes a liquid.