100 Welding Terms You Need to Know

Welding is a complex metal joining process that can be confusing to complete beginners, but understanding basic terms can make a significant difference in the quality of your work.

In this article, we'll delve into the basic welding terminology for beginners and explore the most commonly used terms in the industry.

Keep in mind that the welding glossary contains thousands of welding-related terms, but we will focus more on the ones that will help you understand welding basics and make following our blog posts easier.

Welding Terminology From A to Z

A

Arc: a welding arc formed between a consumable or non-consumable electrode and the base material using either direct (DC) or alternating (AC) currents.

Amperage: refers to how fast the electrons are moving in a circuit. The number of amps produced by the welding machine determines the amount of heat used to melt the electrode and the workpiece.

Alternating Current: electrons oscillate back and forth from the positive to the negative side of the cycle. AC is commonly used to weld non-ferrous and precious metals such as aluminum, magnesium, copper, and titanium.

Alloy: a substance that is added to the base metal to increase its properties such as corrosion resistance, strength, or ductility. Alloys are made by melting the substances, mixing them, and then letting them cool to room temperature.

Acetylene: a colorless hydrocarbon gas that ignites with a dazzling flame. It is used as a fuel gas in the oxyacetylene welding process.

Arc Blow: a phenomenon in DC arc welding when the arc stream does not follow the shortest path between the electrode and the workpiece. Arc wonders around the joint due to the thermal or magnetic properties of base metal.

B

Bead: a result of depositing filler material on and in the work surface when the wire or electrode is melted and fused into the base metal.

Bevel: the process of preparing metal to be welded, usually by cutting an angled slope on the edge of the metal. It is commonly used to ensure better penetration on thicker pieces of metal.

Backhand Welding: a welding technique, also known as pull welding, or welding from left to right, while applying the torch before the rod.

Bare electrode: a welding electrode that has no coating that would protect it from atmospheric contaminations. Bare metal arc welding was the first process that yielded brittle welds due to contamination.

Base metal: the metal you are about to weld or cut, often referred to as parent metal.

Brazing: a process for joining two pieces of metal using heat provided by a torch and a filler metal that melts at 800 ºF (427 ºC).

Butt joint: a simple welding design where the joint is formed simply by placing two pieces of metal end-to-end and welding along the join

C

Cap: the last pass in a multi-pass weld sequence used to cover the entire weld joint with a layer of weld metal.

Coated Electrode: an arc welding electrode protected by a layer of flux that forms a layer of slag that protects the molten metal from atmospheric contamination.

Concavity: the maximum distance from the face of a concave fillet weld perpendicular to a line joining the weld toes.

Corner Joint: a simple weld design where the edges of two plates butt up to each other at a 90-degree angle, forming the letter L to achieve a very strong and durable weld.

Closed Circuit: when you touch the base metal with your electrode, the electrical energy circuit is complete. The current is flowing between the electrode and work, and you are welding.

Crack: a weld defect occurring when internal stresses exceed the strength of the weld metal, the base metal, or both. The weld becomes weak to sustain heavy pressure, leading to failure.

Crater: a weld defect that represents the unfilled end of a weld. It occurs once you stop the welding arc too soon, not allowing it to fill the end of the weld.

Critical Temperature: a temperature that defines the phase transition between two substances from one crystalline form to another.

Cylinder: a portable cylindrical container that stores compressed gas, usually a shielding gas required for welding.

D

Direct Current: the current is flowing one way, from the negative to positive (Cathode to Anode) side of the welding circuit. Direct current arc welding is widely used to weld steel or stainless steel.

Direct Current Electrode Negative (DCEN, Straight Polarity): a setup where the electrode is connected to the negative side and the earth clamp to the positive side of the terminal. The electrons flow from the electrode (torch) to the base metal, causing higher penetration in TIG welding.

Direct Current Electrode Positive (DCEP, Reverse Polarity): a setup where the electrode is connected to the positive and the work clamp is connected to an opposing side of the terminal. The electrons jump from the base metal to the electrode, causing cleaning action and lower penetration in TIG, but it is standard for Gas Metal Arc Welding and Stick welding.

Discontinuity: a flaw that represents a lack of mechanical, physical, or metallurgical harmony in the weld that manifests as porosity, lack of fusion, uneven beads, etc.

Ductility: measures the way that metals are able to withstand tensile, stretching, or stress without breaking.

Duty Cycle: a representation of how long a machine can run at certain amperage in ten minutes before it overheats. A duty cycle of 60% means you can weld interrupted for 6 minutes at specific amps before waiting for a 4-minute cooldown period.

Distortion: the welded component fails to maintain its original shape due to expansion and contraction caused by heating or cooling. It results in shrinkage, angular movement, or buckling.

E

Edge Joint: weld design used to join parts that are parallel to each other or nearly parallel to bind pieces together and distribute stresses.

Edge Preparation: beveling, machining, or hand tooling the edges of a plate or pipe before welding to ensure a sound weld.

Electrode: is used to conduct current through a workpiece to fuse two pieces together. An electrode is called a "rod" in stick welding, and a "wire" for MIG and Flux Cored Arc Welding. TIG welding utilizes non-consumable electrodes made of tungsten.

Electric arc: a welding arc that melts the base metal and filler metal to join pieces, created by an electrical source.

Electrode Holder: an accessory in Stick welding that holds a welding rod and conducts electricity out of the rod.

F

Ferrous Metal: metal that contains iron as the primary element, such as alloy steel, carbon steel, cast iron, and wrought iron.

Filler Metal: additional metal that is added into the weld joint to fill the space between two close-fitting materials.

Fillet Weld: a type of welding joint in which two pieces of metal are joined together at approximately right angles, and the metal is deposited in a fillet weld cross-section.

Flow Meter: an accessory that allows you to control the flow of shielding gas used to protect the weld.

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Flux: a mixture of various minerals, chemicals, and alloying materials that primarily protect the molten weld bead from contamination by oxygen and nitrogen, and other contaminants in the atmosphere.

Flux-Cored Arc Welding (FCAW): a wire welding process that utilizes a continuously-fed flux-cored wire. It is similar to MIG welding, but you don't need a shielding gas which makes it suitable for outside work.

Fumes: heating base metal or filler metal to melting point causes the production of fumes. These are a complex mixture of metals metallic oxides, silicates, and fluorides, which makes them toxic.

Fusion: melting the filler metal and base metal fuses two pieces of metal, causing a very strong bond.

Flat Position: the workpieces that are to be welded are placed flat. An electric arc is passed over the workpieces in a horizontal direction.

Forehand Welding: welding technique in which the flame or electrode advances in the direction of the weld progression.

G

Galvanized: an electrochemical process where mild steel is hot-dipped into liquid zinc to create an anti-corrosive layer.

Gas Metal Arc Welding (GMAW) or MIG welding: one of the most popular welding processes, known for its good results and ease of use. A power source (MIG welder) continuously feeds the solid wire through a MIG gun and deposits it into a joint, which is protected by shielding gas.

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Gas Tungsten Arc Welding (GTAW) or TIG Welding: is a highly specialized process that uses a non-consumable tungsten electrode and a power source (TIG welder) to produce an arc. If required, the filler rod is manually fed into a joint. TIG welding is known for its excellent heat control and weld quality, which makes it suitable for delicate metals and once the highest quality welds are required.

Gas Welding: a metal joining process in which the heat required to join the pieces is obtained from a gas flame, often referred to as Oxyfuel welding.

Groove weld: a grooved opening in the beveled piece over the root opening, that needs to be filled with filler metal.

H

Heat Affected Zone: an area of metal around the weld that has not been melted, but it has undergone changes in properties as a result of being exposed to relatively high temperatures during welding.

Hand Shield: a handheld tool used to protect the face and neck from heat, and eyes from radiation during welding.

Heat Treatment: the material is heated up and cooled down, using predefined methods to achieve the desired mechanical properties like metallurgical structure, hardness, toughness, strength, etc.

I

Inverter: a power source that uses solid-state electronic parts to improve efficiency in the electric current conversion. Inverter welders are smaller, lighter, and more efficient than traditional (transformer) welding machines.

Inert Gas: a gas that chemically does not interact with the base metal or filler metal.

Intermittent Weld (Skip Weld or Stitch Weld): laying multiple welds with spacing between your welds instead of having one long continuous weld to reduce heat buildup on thin pieces.

J

Joint: point or edge where two or more pieces are joined together.

Lap Joint: when the surfaces of the two pieces overlap one another. The weld is deposited in the joint where the two intersect.

K

Kerf: the width of a cut or width of a material that is removed by a cutting process.

L

Leads: an encased cable of stranded wire used to conduct electricity and power an electrode from an arc welding machine.

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M

Melting Point: the temperature at which a metal starts to melt.

Manual Welding: a welding procedure manually performed by a welder.

Multipass Welding: filling a large gap by using multiple welds on top of each other.

Multi-process Welder: a welding machine that can be used for more than one or two welding processes (MIG/Flux core/TIG/Stick or even cutting).

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N

Non-Ferrous: metals that do not contain any appreciable amounts of iron such as copper, aluminum, nickel, etc.

Nozzle: a brass attachment to the end of the welding torch that directs the gas into the weld puddle and protects the contact tip from molten metal.

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O

Open Circuit: occurs once you raise your electrode from the weld. the electricity is not being grounded, so if you touch the electrode, you can easily serve as earth ground and get shocked.

Overlap: molten metal that flows over the surface of the base material and then cools without fusing with the base material

P

Plug Weld: fusing two metals together by making a weld inside small circular holes.

Penetration: a depth of fusion into the parent metal or previous pass from the surface.

Polarity: the direction of current flow when welding, depending on the terminal of the electrode and the work clamp.

Porosity: impurity in the weld shown as small holes of trapped gas or contaminants.

Pre Heating: heating the base metal before welding to reach desired welding properties, slow cooling rate to reduce thermal stress and get rid of moisture.

Post heating: heating the base metal after welding to stop it from cooling down fast and cracking.

Plasma Arc Cutting Process: a fabrication process that employs a power source (Plasma cutter) a superheated, ionized gas funneled through a plasma torch to heat, melt and, ultimately, cut electrically conductive material into custom shapes and designs.

Puddle: a molten pool of metal that forms when two pieces of metal are joined together through welding.

Pulsed Welding: the current pulses between high and low amperage to reduce the heat input while retaining good penetration.

Q

Quenching: the rapid cooling of a metal to adjust the mechanical properties of its original state.

R

Radiation: welding arc emits intense visible, ultraviolet, and infrared radiation that can cause skin burns and eye damage.

Root Opening: a separation at the joint between the workpieces when welding two plates or pipes that are beveled, commonly used in pipe welding.

S

Seam: the seam is right where the two plates, strips, etc. touch. Seam welding is a method of joining workpieces made of similar or dissimilar materials along a continuous seam.

Semi-Automatic Welding: manual welding with equipment that automatically controls one or more of the welding conditions.

Self Shielded Wire (Flux Core Wire, Gasless Wire): a tubular filler wire and electrode filled with flux and used for Flux-cored arc welding FCAW.

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Shielded Metal Arc Welding (Stick welding, MMA welding): one of the oldest welding methods that utilize covered welding rods and an electric power source to join a variety of different metals.

Shielding Gas: a gas, or a mixture of gases that creates a protective atmosphere around the weld, protecting the molten metal from atmospheric gases such as oxygen, hydrogen, or nitrogen.

Slag: a protective layer of solidified flux melted from the electrode or inside the wire that protects the weld metal from defects and contamination.

Soldering: metal joining process that utilizes flame as a source and a filler metal (solder) with a melting point lower than 800 ºF.

Spatter: droplets of molten metal that don't end up in the weld and that need to be cleaned.

Solid Wire: a type of filler metal electrode used for MIG welding, that must be protected by shielding gas.

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Stick-out: how far the wire sticks out from the end of the nozzle in MIG welding.

Stud welding: an electric arc process that rapidly joins a fastener to a base metal or substrate.

Stringer Bead: a narrow, straight weld bead that is created by moving the electrode straight along the weld joint

Submerged Arc Welding: a common arc welding process that uses a continuously fed electrode to create an arc, which is submerged under the blanket of powdered flux.

T

Tack Weld: small weld used to hold two pieces in place until you weld them across the seam.

Tee Joint: a joint between two members at right angles to each other in the form of a letter "T".

Tensile Strength: a maximum amount of force that can be applied to the weld before it breaks

Tungsten Electrode: a non-consumable electrode used in TIG welding, capable of withstanding high temperatures.

U

Undercut: a weld defect that occurs once metal fails to fill in that grooved area due to improper fusion or underfilling of the weld.

Underfill: a weld defect that occurs due to the lack of the deposited weld metal into the weld.

Underwater Welding: welding underwater in a hyperbaric chamber, or wet conditions.

V

Vertical Welding: a welding position in which the axis of the weld is approximately vertical.

Voltage: the force that makes the electrons flow through the conductor. Voltage controls the arc length which is the distance between the molten weld pool and the wire filler metal at the point of melting within the arc.

W

Warping: deformation on the thin pieces either by twisting, bowing, or bending because of heat from the arc.

Weave Bead: a wide weld bead used to fill larger gaps. It is created by weaving the electrode in specific patterns.

Welding: a fabrication process whereby two or more parts are fused together by means of heat, pressure or both forming a join as the parts cool.

Weld Metal: that part of a weld that is melted during welding.

Weld Symbol: symbol on a blueprint or drawing that specifies a desired weld process, length, location, number of welds, and more.

Weldability: the ability of any material (usually metals and its alloys) to weld with similar materials and form a strong, lasting bond.

Welder Certification: formal assessments that verify and prove a welder's ability and knowledge of handling and maintaining equipment, as well as welding.

Weld Test: testing the durability and other properties of achieved welds either by Visual tests, Destructive tests, and Non-Destructive tests.

Welding Helmet: a crucial piece of PPE (Personal Protective Equipment) that will protect your eyes.

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Welding Rod: a rod (TIG, Stick) or heavy wire (MIG/Flux core) that melts and thus supplies metal in fusion welding.

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Welding Torch: an accessory used in TIG welding or gas welding to produce and control the arc.

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Wire Feed Speed: the rate at which filler wire is deposited into the weld in MIG or Flux-cored Arc welding.

Work clamp: ensures the electrical welding circuit is closed between the welding power source and the piece to be welded.

X

X-ray: a radiographic test method that detects defects inside a weld that cannot be observed by visual inspection.

Y

Yield Strength: the amount of stress a material can withstand before it begins to deform plastically.

Z

Zinc: a slightly brittle metal, mainly used as a coating to protect iron and steel from corrosion (galvanized metal), as alloying metal to make bronze and brass.