Welding Terminology A-Z

Welding, an essential craft in the world of metalworking, serves as the foundation for creating strong and lasting connections between metal pieces. From building structures to crafting machinery, welding is a vital part of various industries, influencing our daily lives in ways we may not even realize. To truly appreciate the art of welding, it’s important to grasp the language that welders use to communicate and understand their work. This article aims to simplify the terminology associated with welding, making it accessible and engaging for aspiring welders around the world. Whether you’re just starting to explore the world of welding or are simply curious about the process, join us as we break down the key terms that form the backbone of this transformative skill.

Weld Terminology From A-Z

A-Number : A designation for ferrous weld metal for procedure qualification based upon chemical composition of weld deposit.

Acetone: This flammable liquid is utilized in welding to dissolve and stabilize acetylene, a gas type, within high-pressure cylinders.

Acetylene: A combustible gas composed of carbon and hydrogen, frequently employed as a fuel in welding processes.

Acceptable Weld : A weld that meets the applicable requirements

Actual throat: Describes the THROAT OF FILLET WELD, indicating the measurement from the weld’s root to the center of its face.

Active Fluxes : Active fluxes produce changes in weld metal chemistry when welding is changed. Active fluxes are restricted to single or minimal multi-pass welding.

Aging : The procedure of allowing metals or alloys to stabilize at room temperature following shaping or heat treatment. This is done to enhance dimensional stability or improve hardness and strength through structural changes, often achieved by precipitation.

Agglomerated Flux : Granular flux created by heating a pelletized blend of powdered ingredients and bonding agents at a temperature adequate to eliminate moisture, then processed to achieve the desired particle size.

Air-Acetylene: A welding flame variety generated by burning acetylene with air rather than oxygen is known as an oxy-acetylene flame.

Air Carbon Arc Cutting – A variation of the carbon arc cutting process that eliminates molten metal using a stream of air.

Alloy : A mix of two or more elements, including at least one metal, that has metallic properties.

Allotropic : A substance where atoms have the ability to transition into two or more crystalline structures at varying temperatures.

Alternating current (AC): Alternating Current (AC) is an electric current that reverses direction periodically, forming a sine wave. It is widely used for efficient power distribution and operates key electrical devices in homes, industries, and various applications.

Ammeter: An instrument used to gauge the electric current within a circuit.

Annealing: The method of gradually heating and cooling steel to modify its characteristics, such as rendering it more pliable or modifying its internal structure.

Arc Blow : The deviation of an electric arc from its typical trajectory caused by magnetic forces.

Arc Cutting : Cutting methods in which materials are melted due to the heat generated by the arc between the electrode and the metal.

Arc Force : The axial force generated by plasma formed by the arc.

Arc Length : The distance from the tip of the welding electrode to the nearby surface of the weld pool.

Arc Strike :

Arc Time : The time during which an arc is maintained in making an arc weld.

Arc Voltage : the voltage that runs along the welding arc.

Arc Weld Deposition Efficiency – The percentage expressing the ratio of the weight of deposited filler metal in the weld to the weight of melted filler metal.

Arc Welding : welding methods where fusion is achieved by heating the materials to be joined using an electric arc(s). This may be done with or without filler material.

As Cast Structures –The crystalline structure before stress relief through rolling or hammer forging.

As Welded : The condition of the weld and welded joints immediately after welding and prior to any subsequent treatments.

Austenite : A non-magnetic variation of iron formed by heating steel above a specific temperature, capable of absorbing significant amounts of carbon and other elements.

Autogenous Weld : a fusion weld created without incorporating additional filler material


Back Fire: The momentary recession of the flame into the oxyful torch, posing a potential risk of flashback. Typically indicated by a popping sound, the flame may subsequently either extinguish or reignite at the tip’s end.

Back-gouging – The removal of weld metal and base metal from the weld root side of a welded joint to enable thorough fusion and complete joint penetration during subsequent welding from that side.

Back Pass: A pass made to deposit a back weld.

Backhand Welding : A welding method where the flame from the welding torch or gun is directed towards the completed weld.

Backing Gas : A gas employed to shield the root side of a weld joint is commonly known as a “backing gas.

Backing Ring – Backing in the shape of a ring, typically employed in pipe welding.

Backing Strip: A material employed to hold molten metal at the weld root and/or enhance the joint’s thermal capacity to mitigate excessive warping of the base metal.

Backing Weld: A weld bead administered at the root of a single groove joint to ensure thorough penetration of the root.

Bare electrode : An arc welding electrode with no coating except for what naturally occurs during the wire drawing process.

Bare Metal-Arc Welding : An arc welding method where fusion is achieved by heating with an unshielded arc formed between a bare or lightly coated electrode and the workpiece. No pressure is applied, and the filler metal is derived from the electrode.

Base Metal – The metal or alloy that is welded, brazed, soldered, or cut.

Bevel : An angular edge shape.

Bevel Angle – The angle created between the cut surface and an imaginary plane perpendicular to the plate surface. Plasma arc cutting typically results in the removal of more metal from the top than the bottom, generating a cut angle, also known as the cut angle itself.

Bead Weld: A weld type consisting of one or more string or weave beads deposited on a continuous surface.

Binary Alloy : An alloy composed of two elements.

Block Brazing: A brazing technique where bonding is achieved through the heat generated by heated blocks applied to the parts to be joined. It involves the use of a nonferrous filler metal with a melting point above 800 ºF (427 ºC) but below that of the base metal. Capillary attraction is utilized to distribute the filler metal in the joint.

Blowhole : A flaw in metal arising from rapid cooling of hot metal when an excess of gaseous content is present. In welding, it refers to a gas pocket within the weld metal formed as a result of the hot metal solidifying before all gases have escaped to the surface.

Bond: The junction of the welding metal and the base metal.

Bonded Fluxes : Manufacturing of bonded fluxes involve binding a variety of powders together and then baking them at a low temperature. The primary benefit is the ability to introduce additional alloying ingredients into the mixture.

Brazing : A brazed weld is created by heating an assembly to the brazing temperature, employing a filler metal with a liquidus above 450°C (840°F) and below the solidus of the base metal. Capillary action is utilized to distribute the filler metal between the closely fitted faying surfaces of the joint.

Braze welding: Welding is performed using a filler metal that melts above 450 ºC (842 ºF) and below the solid state of the base metals in braze welding. In contrast to brazing, capillary action is not employed to distribute the filler metal within the joint.

Buildup Sequence: The order in which the weld beads of a multipass weld are deposited with respect to the cross section of a joint.

Brittleness : The tendency of a material to fail suddenly by breaking, without any permanent deformation of the material before failure.

Buildup : A surfacing modification wherein surfacing material is applied to attain the necessary dimensions. Also referred to as buttering, cladding, and hard-facing.

Butt Joint : A joint between two workpieces in such a manner that the weld joining the parts is between the surface planes of both of the pieces joined.