A Glossary of Welding Terms

welding glossary

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If you’re starting a welding career, you will learn a lot of welding terminology. It may seem a bit overwhelming at first, but you’ll get the hang of it during your welding training. To get you started, here’s a compilation of the most commonly used welding terms:


A metal made from two or more combined elements.


Annealing is the slow cooling of the metal to reduce internal stresses, make the material softer and change ductility, among other things.

Arc Welding

A general term that applies to many kinds of welding. The common denominator is using an arc to create heat. Arc welding may also use other filler materials or pressure to create a weld.

Base Metal

This has two meanings: 1) the metal that will be cut or welded; 2) in an alloy, it is the largest proportion of the metal.

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The point where the welding metal is joined with the base metal.


This welding technique uses a filler metal to create a bond. The filler metal is nonferrous and has a melting point below the melting point of the base metal.

Carbon-Arc Welding

A welding method that involves creating an arc between a carbon electrode and a metal.

Case Hardening

This process hardens the surface of the metal by using inward diffusion with gasses or a liquid before applying heat.

Coated Electrode

The electrode is covered with flux through dipping or painting. When heat is applied, the flux produces a gas that shields the arc.

Covered Electrode

The metal electrode is covered with asbestos, flux, paper or other materials to make the arc more stable and improve the welding metal.

Critical Temperature

The temperature at which the material transitions from one crystalline form to another.

Current Density

The amount of amperes applied per square inch across a particular area.

Cutting Torch

This welding tool controls gas for preheating the metal, as well as the oxygen for cutting the metal.

Direct Current Electrode Negative (DCEN)

The metal being welded is the positive pole, and the electrode is the negative pole of the arc.

Direct Current Electrode Positive (DCEP)

DCEP is the opposite of DCEN. The welded metal is the negative pole, and the electrode is the positive pole of the arc.

Electric Arc

An electrical current that forms in the gap between two electrodes creates an electric arc.


There are many types of electrodes used in welding. An electrode conducts the electrical current through a work piece to create the weld. Some electrodes are consumed in the welding process while others are not.

Filler Material

This is the metal that is added when making a weld.

Flame (Oxygen) Cutting

The chemical action of oxygen applied to the elements in the base metal at high temperatures cuts ferrous metals.

Flame (Oxygen) Gouging

This method is used to create a groove in the metal using an oxygen-cutting tool.

Flame Hardening

The metal surface is hardened using a heated flame, followed by a quick quench.

Flame Softening

This technique makes metal softer by first heating it and then slowly letting it cool down.


This material cleans metals to prepare them for welding.

Forehand Welding

The flare is aimed at the metal ahead of the completed weld.

Gas Carbon-Arc Welding

The weld is accomplished by an electrical arc between a carbon electrode and the welding metal. Argon or helium gas provides the shielding.

Gas Metal-Arc Welding (GMAW)

The heat from the arc produced between the electrode and the metal results in a weld. A gas like helium provides the shielding. This technique is also called Metal-Inert-Gas (MIG) welding.

Gas Tungsten-Arc Welding, GTAW

Also called Tungsten-Inert-Gas (TIG) welding, this arc welding method uses an electrode made from tungsten with inert gas.

Gas Welding

Welding type where the heat for welding comes from a gas flame.

Groove Weld

Creating this weld requires filler material that goes in the groove between two metals to join them.

Hammer Welding

Hammering two pieces of heated metal together.

Hydrogen Brazing

A type of brazing in a furnace under a hydrogen atmosphere.

Hydromatic Welding

This method is also called pressure-controlled welding. Spot welds are made in a sequence using more than one electrode under pressure.

Inert Gas

Gas that doesn’t combine chemically with metal.

Ionization Potential

The amount of electrical voltage needed to create ionization of the materials, which either adds or removes electrons.


The area where materials are fused together.


The width of a piece of metal removed by cutting.


The lowest temperature at which the metal or alloy turns liquid.

Metal-Arc Welding

This arc welding method uses metal electrodes.

MIG Welding

See gas metal arc welding (GMAW).

Multi-Impulse Welding

Making more than one weld by using multiple pulses of electricity.


These metals do not have any iron, such as titanium, nickel, lead, copper, bronze, brass and aluminum.


In this process, iron-based alloys are heated to 100°F above the critical temperature and then allowed to cool down in air temperature.

Oxyacetylene Welding

The temperature needed for welding comes from burning a combination of acetylene and oxygen.

Oxy-Natural Gas Welding

In this welding process, the heat necessary to make the weld comes from burning natural gas with oxygen.

Oxy-Hydrogen Welding

The heat source for this welding method is a mixture of oxygen and hydrogen.

Oxy-Propane Welding

The heat for welding comes from burning a mixture of oxygen and propane.


Small hammer blows stretch the surface of cold metals and reduce stress in the metal.

Percussive Welding

This method involves applying high temperature to the welding site, just before pressure is applied.

Plasma Arc Welding

In this welding process, a constricted arc is created between a non-consumable electrode and the weld pool or between an electrode and the constricting nozzle. Ionized Gas coming out of the torch provides the necessary shielding.

Plug Weld

A hole is cut in one piece of metal. Another piece of metal is put behind the hole, and the weld is made in the hole to connect the two pieces of metal.


This means that gas pocket or inclusions are present in the welded material.

Pressure Controlled Welding

This welding technique creates spot or projection welds in sequence with pressure applied to the weld made by multiple electrodes.

Pressure Welding

Pressure fuses the materials.

Projection Welding

A resistance welding technique used between two surfaces or the ends of one member and the surface of another.

Pulsation Welding

The welds for each spot receive more than one electrical pulse without the electrode moving or releasing the pressure.


The rapid cooling of metal using water, air or oil.

Resistance Welding

Heat is generated through the resistance to the electric current flowing through the circuit of which the welded metal is a part.

Root of Joint

This is the part where the materials are joined are the smallest distance from each other, which could be an area, a line or a point.

Root of Weld

The point where—when observed from a cross-section viewpoint—the bottom of the weld fuses with the base metal.

Seal Weld

The main purpose of this weld is to get a tight connection and prevent leaks.

Seam Welding

This weld forms a long line that connects joints in the welded material.[1][2]

An easy way to memorize what all these different terms mean is to apply them during your vocational training. Before you know it, many of these welding terms will be part of your daily language.

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