Everything you need to know about laser welding. Almost.

Laser welding is a multi-faceted process that includes materials, processes, technology and expertise customized to meet specific engineering requirements. Learning all that laser lingo can be a challenge, so we’ve provided this glossary to make understanding laser a little easier.  Can’t find what you need here?  Don’t hesitate to just Ask ARCOR.

Abrasive – Slag used for cleaning or surface roughening.

Alloying – Adding a metal or alloy to another metal or alloy.

Annealed Condition – A metal or alloy that has been heated and then cooled to remove internal stresses and to make the material less brittle.

Arc Welding – A group of welding processes which produces coalescence of metals by heating them with an arc, with or without the application of pressure and with or without the use of filler metal.

As-Welded – The condition of the weld metal, after completion of welding, and prior to any subsequent thermal or mechanical treatment.

Austenitic – Composed mainly of gamma iron with carbon in solution.

Autogenous Weld – A fusion weld made without the addition of filler metal.

Automatic – The control of a process with equipment that requires little or no observation of the welding and no manual adjustment of the equipment controls.

Backing – A material (base metal, weld metal, or granular material) placed at the root of a weld joint for the purpose of supporting molten weld metal.

Backing Gas – A shielding gas used on the underside of a weld bead to protect it from atmospheric contamination.

Backing Ring – Backing in the form of a ring, generally used in the welding of pipe.

Base Metal (material) – The metal (material) to be welded, brazed, soldered, or cut. See also substrate.

Bend Radius – Radius of curvature on a bend specimen or bent area of a formed part. Measured on the inside of a bend.

Blanking – Process of cutting material to size for more manageable processing.

Brazing – A group of welding processes which produces coalescence of materials by heating them to a suitable temperature and by using a filler metal, having a liquidus above 840 °F (450 °C) and below the solidus of the base materials. The filler metal is distributed between the closely fitted surfaces of the joint by capillary attraction.

Burr – A rough ridge, edge, protuberance, or area left on metal after cutting, drilling, punching, or stamping.

Butt Joint – A joint between two members lying in the same plane.

Camber – Deviation from edge straightness, usually the greatest deviation of side edge from a straight line.

Cosmetic Pass – The final pass of a weld joint.

Cladding – A thin (> 0.04″) layer of material applied to the base material to improve corrosion or wear resistance of the part.

Clad Metal – A composite metal containing two or three layers that have been welded together. The welding may have been accomplished by roll welding, arc welding, casting, heavy chemical deposition, or heavy electroplating.

Complete Fusion – Fusion that has occurred over the entire base material surfaces intended for welding, and between all layer and passes.

Complete Joint Penetration – Joint penetration in which the weld metal completely fills the groove and is fused to the base metal throughout its total thickness.

Crack – A crack in the weld bead visual to 20X to 50X magnification.

Cryogenic – Refers to low temperatures, usually -200 o (-130 o) or below.

Defect – A discontinuity or discontinuities that by nature or accumulated effect (for example, total crack length) renders a part or product unable to meet minimum applicable acceptance standards or specifications.

Deposited Metal – Filler metal that has been added during welding, brazing or soldering.

Deposition Rate – The weight of material deposited in a unit of time. It is usually expressed as pounds/hour (lb/h) or kilograms per hour (kg/h).

Depth of Fusion – The distance that fusion extends into the base metal or previous pass from the surface melted during welding.

Dilution – The change in chemical composition of a welding filler material caused by the admixture of the base material or previously deposited weld material in the deposited weld bead. It is normally measured by the percentage of base material or previously deposited weld material in the weld bead.

Electron Beam Welding – A welding process producing coalescence of metals with molten slag which melts the filler metal and the surfaces of the work to be welded. The molten weld pool is shielded by the slag, which moves along the full cross section of the joint as welding progresses.

Facing Surface – The surfaces of materials in contact with each other and joined or about to be joined together.

Filler Material – The material to be added in making a welded, brazed, or soldered joint.

Fillet Weld – A weld of approximately triangular cross section that joins two surfaces approximately at right angles to each other in a lap joint, T-joint, or corner joint.

Friction Welding – A solid welding process which produces coalescence of material by the heat obtained from a mechanically induced sliding motion between rubbing surfaces. The work parts are held together under pressure.

Friction Stir Welding – A solid-state welding process, which produces coalescence of material by the heat obtained from a mechanically induced rotating motion between tightly butted surfaces. The work parts are held together under pressure.

Forehand Welding – A welding technique where the welding torches or gun is pointed toward the direction of welding.

Fusion – The melting together of filler metal and base metal (substrate), or of base metal only, which results in coalescence.

Gas Metal Arc Welding (GMAW) – An arc welding process where the arc is between a continuous filler metal electrode and the weld pool. Shielding from an externally supplied gas source is required.

Gas Tungsten Arc Welding (GTAW) – An arc welding process where the arc is between a tungsten electrode (non-consumable) and the weld pool. The process is used with an externally supplied shielding gas.

Gas Welding – Welding with the heat from an oxy-fuel flame, with or without the addition of filler metal or pressure.

Groove Weld – A weld made in a groove between two members. Examples: single V, single U, single J, double bevel etc.

Hard-Facing – Surfacing applied to a workplace to reduce wear.

Heat-Affected Zone – That section of the base metal, generally adjacent to the weld zone, whose mechanical properties or microstructure, have been altered by the heat of welding.

Hermetically Sealed – Airtight. Heterogenous –


Hot Crack – A crack formed at temperatures near the completion of weld solidification.

Incomplete Fusion – A weld discontinuity where fusion did not occur between weld metal and the joint or adjoining weld beads.

Incomplete Joint Penetration – A condition in a groove weld where weld metal does not extend through the joint thickness.

Inert Gas – A gas that normally does not combine chemically with the base metal or filler metal.

Intergranular Penetration – The penetration of filler metal along the grain boundaries of a base metal.

Joint – The junction of members or the edges of members that are to be joined or have been joined.

Kerf – The width of the cut produced during a cutting process.

Keyhole – A technique of welding in which a concentrated heat source penetrates completely through a work-piece forming a hole at the leading edge of the molten weld metal. As the heat source progresses, the molten metal fills in behind the hole to form the weld bead.

Lap Joint – A joint between two overlapping members in parallel planes.

Laser – A device that provides a concentrated coherent light beam. Laser is an acronym for Light Amplification by Stimulated Emission of Radiation.

Laser Beam Cutting – A process that severs material with the heat from a concentrated coherent beam impinging upon the work-piece.

Laser Beam Welding – A process that fuses material with the heat from a concentrated coherent beam impinging upon the members to be joined.

Leg of Fillet Weld – The distance from the root of the joint to the toe of the fillet weld.

Liquidus – The lowest temperature at which a metal or an alloy is completely liquid.

Mandrel – A metal bar serving as a core around which other metals are cast, forged, or extruded, forming a true, center hole.

Martensitic – An interstitial, super-saturated solid solution of carbon in iron, having a body-centered tetragonal lattice.

Manual Welding – A welding process where the torch or electrode holder is manipulated by hand. MIG – See Gas Metal Arc Welding (GMAW).

Mechanical Bond – The adherence of a thermal-spray deposit to a roughened surface by particle interlocking.

Mechanized Welding – Welding with equipment where manual adjustment of controls is required in response to variations in the welding process. The torch or electrode holder is held by a mechanical device.

Melting Range – The temperature range between solidus and liquidus.

Melt-Through – Visible reinforcement produced on the opposite side of a welded joint from one side.

Plasma – A gas that has been heated to at least partially ionized condition, enabling it to conduct an electric current.

Plasma Arc Welding (PAW) – An arc welding process that uses a constricted arc between a non-consumable electrode and the weld pool (transferred arc) or between the electrode and the constricting nozzle (non-transferred arc). Shielding is obtained from the ionized gas issuing from the torch.

Plasma Spraying (PSP) – A thermal spraying process in which a non-transferred arc is used to create an arc plasma for melting and propelling the surfacing material to the substrate.

Plug Weld – A circular weld made through a hole in one member of a lap or T joint.

Porosity – A hole-like discontinuity formed by gas entrapment during solidification.

Post-Heating – The application of heat to an assembly after welding, brazing, soldering, thermal spraying, or cutting operation.

Postweld Heat Treatment – Any heat treatment subsequent to welding.

Preform – The initial press of a powder metal that forms a compact.

Preheating – The application of heat to the base metal immediately before welding, brazing, soldering, thermal spraying, or cutting.

Preheat Temperature – The temperature of the base metal immediately before welding is started.

Procedure Qualification – Demonstration that a fabricating process, such as welding, made by a specific procedure can meet given standards.

Reinforcement – Weld metal, at the face or root, in excess of the metal necessary to fill the joint.

Residual Stress – Stress remaining in a structure or member, as a result of thermal and/or mechanical treatment. Stress arises in fusion welding primarily because the melted material contracts on cooling from the solidus to room temperature.

Root Opening – A separation at the joint root between the work pieces.

Root Crack – A crack at the root of a weld.

Shielded Metal Arc Welding (SMAW) – A process that welds by heat from an electric arc, between a flux-covered metal electrode and the work. Shielding comes from the decomposition of the electrode covering.

Shielding Gas – Protective gas used to prevent atmospheric contamination.

Soldering – A joining process using a filler metal with a liquidus less than 840 °F and below the solidus of the base metal.

Solid State Welding – A group of welding processes which produces coalescence at temperatures essentially below the melting point of the base materials being joined, without the addition of a brazing filler metal. Pressure may of may not be used.

Solidus – The highest temperature at which a metal or alloy is completely solid.

Spatter – Metal particles expelled during welding that do not form a part of the weld.

Stress Relief Heat Treatment – Uniform heating of a welded component to a temperature sufficient to relieve a major portion of the residual stresses.

Stress Relief Cracking – Cracking in the weld metal or heat affected zone during post-weld heat treatment or high temperature service.

Submerged Arc Welding – A process that welds with the heat produced by an electric arc between a bare metal electrode and the work. A blanket of granular fusible flux shields the arc.

Substrate – Any material upon which a thermal-spray deposit is applied.

Synergistic – An action where the total effect of two active components in a mixture is greater than the sum of their individual effects.

Tack Weld – A weld made to hold parts of a weldment in proper alignment until the final welds are made.

Tensile Strength – The maximum stress a material subjected to a stretching load can withstand without tearing.

Thermal Conductivity – The quantity of heat passing through a material.

Thermal Stresses – Stresses in metal resulting from non-uniform temperature distributions.

TIG Welding – See Gas Tungsten Arc Welding (GTAW).

Torch Standoff Distance – The dimension from the outer face of the torch nozzle to the work piece.

Transferred Arc – In plasma arc welding, a plasma arc established between the electrode and the work-piece.

Underbead Crack – A crack in the heat-affected zone generally not extending to the surface of the base metal.

Undercut – A groove melted into the base plate adjacent to the weld toe or weld root and left unfilled by weld metal.

Vapor Pressure – The pressure exerted by a vapor when a state of equilibrium has been reached between a liquid, solid or solution and its vapor. When the vapor pressure of a liquid exceeds that of the confining atmosphere, the liquid is commonly said to be boiling.

Viscosity – The resistance offered by a fluid (liquid or gas) to flow.

Weldability – The capacity of a material to be welded under the fabrication conditions imposed into a specific, suitably designed structure and to perform satisfactorily in the intended service.

Weld Bead – The metal deposited in the joint by the process and filler wire used.

Welding Leads – The work piece lead and electrode lead of an arc welding circuit.

Welding Wire – A form of welding filler metal, normally packaged as coils or spools that may or may not conduct electrical current depending upon the welding process used.

Weld Metal – The portion of a fusion weld that has been completely melted during welding.

Weld Pass – A single progression of welding along a joint. The result of a pass is a weld bead or layer.

Weld Pool – The localized volume of molten metal in a weld prior to its solidification as weld metal.

Weld Puddle – A non-standard term for weld pool.

Weld Reinforcement – Weld metal in excess of the quantity required to fill a joint.

Welding Sequence – The order in which weld beads are deposited in a weldment.

Wetting – The phenomenon whereby a liquid filler metal or flux spreads and adheres in a thin continuous layer on a solid base metal.

Wire Feed Speed – The rate at which wire is consumed in welding.

Work Lead – The electric conductor between the source of arc welding current and the work.


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