Introduction to FCAW 261

AC

Alternating current. Electricity that reverses direction at regularly recurring intervals of time. In the United States, AC reverses 120 times per second, or 60 hertz.

air-cooled guns

A type of welding gun that uses air or gas as a coolant. Air-cooled guns have a small nozzle on the end to provide the air or gas.

alloying elements

A material that is intentionally added to a metal in order to change its properties. Alloying elements can improve the strength, ductility, hardness, and toughness of a finished weld.

alternating current

AC. Electricity that reverses direction at regularly recurring intervals of time. In the United States, alternating current reverses 120 times per second, or 60 hertz.

alternators

A device that converts mechanical energy into AC energy. An alternator can provide electrical energy to a power source.

American Welding Society

AWS. The non-profit organization that regulates industrial standards for welding. The American Welding Society also promotes the welding industry in the United States.

amperage

The amount of current flowing in a circuit. Amperage is measured in amperes (A), or amps, and is determined by wire feed speed (WFS) in FCAW.

arc length

The distance that electricity must travel from the tip of the electrode to the weld pool. Longer arc lengths require more voltage.

arc stability

A measure of a welding arc’s consistency and predictability. Arc stability is essential during the welding process.

arc welding

A group of welding processes that use electricity to generate the heat needed to melt the base metals and fuse them together permanently. Arc welding processes include shielded metal arc welding (SMAW), gas metal arc welding (GMAW), flux-cored arc welding (FCAW), and gas tungsten arc welding (GTAW).

argon

Ar. A heavy, inert gas commonly used for shielding in arc welding processes. Argon is much heavier than air and can effectively shield the weld area.

atmospheric contaminants

Any element of the surrounding environment that can impact the quality and strength of a finished weld. Atmospheric contaminants are usually ambient gases such as oxygen and nitrogen.

automatic

A type of welding process in which a computer or a robot controls both the welding equipment and the weld variables. In automatic welding, the welder is responsible for setting and controlling the specialized settings for the computer or robot.

AWS

American Welding Society. The non-profit organization that regulates industrial standards for welding. The AWS also promotes the welding industry in the United States.

base metals

One of the metals that are welded together to form a joint. The base metal and its properties influence the type of welding and the type of electrode that should be used.

carbon dioxide

CO₂. A heavy, active gas composed of carbon and oxygen that is commonly used for shielding in arc welding processes. Carbon dioxide breaks down into carbon monoxide in the heat of the arc.

carbon steels

The most basic form of steel, which contains less than 3.0% alloying elements. Carbon steels are divided into low-, mild, medium-, and high-carbon steels.

chemical composition

The type, amount, and arrangement of atoms that, when combined, compose a whole material or substance. Chemical composition can be altered whenever a change occurs at the atomic level.

circuit

A controlled path for electricity. All arc welding processes require a closed electrical circuit that includes a source, path, load, and control.

climate-controlled environment

An environment in which the temperature and humidity are strictly regulated. Climate-controlled environments are ideal for storing FCAW electrodes.

combustible

A material capable of igniting and burning if its temperature is raised. Combustible materials can ignite without being exposed to a flame, unlike flammable materials.

conductors

A material that allows electricity to flow. Conductors are typically metals.

constant voltage

CV. A power supply in which the voltage is set at a fixed level and the amperage varies to maintain relatively constant voltage. With constant voltage power, the wire feed speed (WFS) is also set at a fixed rate and maintained by the varying amperage.

consumable electrode

An electrode that conducts electricity to the arc and also melts into the weld as filler metal. Some consumable electrodes may also provide shielding that protects the arc and weld pool.

contact tip

The device located inside the welding gun that conducts electricity to the electrode. The contact tip is usually made of copper.

contaminants

Any foreign substance that may cause a loss of efficiency or a breakdown. Contaminants in welds include oxygen and nitrogen.

copper

A reddish metal that is very ductile, thermally and electrically conductive, and corrosion resistant. Copper is used to make the contact tips of welding guns.

copper alloy

A metal consisting of two or more elements, one of which is copper. Common copper alloys include aluminum-silicon-copper-magnesium and zinc-aluminum-copper-magnesium.

core

The inner part of an electrode that is surrounded by an outer metal sheath. The core of FCAW electrodes contains flux materials.

corrosion resistance

The ability of a material to resist deterioration and chemical breakdown due to surface exposure to certain conditions. Corrosion resistance is an important physical property of finished welds.

current

The flow of electricity through a circuit. Current strength is measured in amperes (A), or amps, and controls the heat of the arc.

DC

Direct current. Electricity that flows in one continuous direction. DC is required for several common welding processes such as GMAW and FCAW.

defects

An irregularity in the specified and expected composition of a weld that exceeds the part design’s tolerances. A defect is an unacceptable discontinuity.

denitrifiers

A material that removes nitrogen from the molten weld pool and arc. Denitrifiers prevent nitrogen from ruining a weld bead.

density

The amount of material within a specific volume. Objects with greater density have a relatively large amount of weight compared to the amount of physical space they occupy.

deoxidizers

A material that removes oxygen from the molten weld pool and arc. Deoxidizers prevent oxygen from ruining a weld bead.

deposition rates

The rate at which filler metal is deposited into the molten weld pool to form a weld. The deposition rate can be measured in pounds per hour (lb./hr.) or in kilograms per hour (kg/hr).

designators

A character or collection of characters that specifies an electrode’s characteristics and properties in the AWS classification system. Designators can be numbers, letters, or a combination of both.

diffusible hydrogen

The maximum amount of hydrogen, given in milliliters (mL), that will be present per 100 grams (g) of weld metal. An electrode’s classification may specify its diffusible hydrogen.

direct current

DC. Electricity that flows in one continuous direction. Direct current is required for several common welding processes such as GMAW and FCAW.

direct current electrode negative

DCEN. Current that always flows in one continuous direction from the negative electrode to the positive workpiece. Direct current electrode negative polarity is also known as straight polarity, but this is a non-standard term.

direct current electrode positive

DCEP. Current that always flows in one continuous direction from the negative workpiece to the positive electrode. Direct current electrode positive polarity is also known as reverse polarity, but this is a non-standard term.

directly proportional

A relationship in which one number increases or decreases at the same rate and in the same ratio as another number. Directly proportional is the opposite of inversely proportional.

discontinuity

An irregularity in the specified and expected composition of a weld. A discontinuity becomes a defect if it exceeds specifications.

drawing dies

A tool used to form wire or metal into a specified shape. Drawing dies reduce an FCAW electrode’s diameter and compress its core materials during fabrication.

drive rolls

A set of wheels that moves electrode wire through a wire feeder. Drive rolls are specially designed for various types and sizes of electrodes and can be either smooth or knurled.

ductility

A material's ability to be drawn, stretched, or formed without breaking. Ductility generally increases as hardness decreases.

duty cycle

The amount of time in a ten-minute period that an electrical device can perform work before it must rest to prevent overheating. Duty cycle ratings are given as a percentage of the ten-minute period.

electric arc

The area in which electricity jumps from an electrode to a workpiece. Electric arcs produce extreme heat and light.

electric shock

The flow of electricity through the body. Severe electric shock can be fatal.

electrode

A component of an electrical circuit that conducts electricity. Electrodes can also serve as filler metal in some arc welding processes.

electrode cable

The path used in arc welding to conduct electricity from the power source to the electrode. The electrode cable connects the power source to the wire feeder or to the gun.

electrode efficiency rates

The percentage of a welding electrode that becomes filler metal. A higher electrode efficiency rate indicates a lower amount of electrode lost due to spatter or wasted as unusable stubs.

electrode extension

The distance from the end of the contact tip to the end of the electrode. Electrode extension combined with arc length is equal to the contact tip to work distance.

electrode liner

The insulated lining that surrounds the electrode and supports it from the wire feeder to the contact tip in a welding gun. Electrode liners are made of coiled steel wire and can be either permanent or interchangeable.

electrode oven

An enclosed heating device used to store and recondition welding electrodes. Electrode ovens maintain different temperatures depending on the type of electrode.

energy efficient

Having an energy output that is close to the total energy supplied. Energy-efficient devices do work using smaller amounts of electricity, which costs less.

engine-driven power source

A welding machine that converts mechanical energy from an engine into electrical energy. Engine-driven power sources may include alternators that allow them to run both AC and DC.

fabrication

The process of creating or building parts from raw materials and components. Fabrication methods include forming, molding, and joining processes like welding and assembly.

FCAW

Flux-cored arc welding. A semi-automatic or automatic arc welding process that uses a continuously fed consumable electrode with an inner core of flux. FCAW includes both self-shielded flux-cored arc welding (FCAW-S) and gas-shielded flux-cored arc welding (FCAW-G).

FCAW-G

Gas-shielded flux-cored arc welding. A type of FCAW that uses a flux-filled, tubular wire electrode and an external shielding gas to protect the weld area. FCAW-G processes reduce the risk of weld cracking.

FCAW-S

Self-shielded flux-cored arc welding. A type of FCAW that relies on the flux materials within a tubular wire electrode to provide shielding for the weld area. FCAW-S processes do not require external shielding gas.

ferrous metals

A metal that contains iron. Ferrous metals are the most common type of welded metal.

filler metal

Metal deposited into the weld that often adds strength and mass to the welded joint. The electrode provides the filler metal in some arc welding processes.

fire extinguisher

A portable device that uses a rapid spray of chemicals to put out small fires. Fire extinguishers are an essential part of fire prevention.

fire-resistant

Made of materials that are designed to resist burning and withstand heat. Fire-resistant materials are essential to welding safety.

flammable

A material that can ignite and burn if it comes in contact with sparks or fire. Flammable materials can ignite without their temperature being raised, unlike combustible materials.

flat

Welding that is performed from the upper side of a joint. In the flat position, the face of the weld is horizontal.

flowmeters

The device that indicates and controls the volume of shielding gas that flows to the welding gun. The flowmeter consists of a flow gauge that measures the volume and an adjustment valve that controls the volume.

flux

A non-metallic material containing shielding and scavenging elements that is used to protect the weld pool and arc from atmospheric contamination. In FCAW, flux material is contained in the core of the electrode.

flux-cored arc welding

FCAW. A semi-automatic or automatic arc welding process that uses a continuously fed consumable electrode with an inner core of flux. Flux-cored arc welding includes both self-shielded flux-cored arc welding (FCAW-S) and gas-shielded flux-cored arc welding (FCAW-G).

fluxing reactions

A chemical process that cleans and purifies the weld metal. Fluxing reactions occur when flux material vaporizes and combines with the weld metal.

frequencies

The rate at which an alternating electrical current changes direction. Frequency is typically measured in hertz (Hz), or cycles per second.

fume extractor

Any device that uses suction to remove gases and particulate matter from the environment. A fume extractor should almost always be used during welding.

fume plume

A cloud-like area above the arc containing welding gases, metallic fumes, and particulates. The fume plume can present an inhalation risk if safety precautions are not followed.

fumes

Airborne particulate matter that behaves similar to a gas. Welding fumes include particulates from the electrode, base metal, and any coatings included on the welding materials.

gas cylinders

A metal container used to store pressurized gases for manufacturing purposes. Gas cylinders are built specifically for each gas and have different properties depending on the gas.

gas diffuser

A device inside a welding gun through which shielding gas flows. The gas diffuser regulates the flow of gas.

gas hoses

A flexible tube used to deliver shielding gas. Gas hoses run from the gas cylinder to the welding gun.

gas marking

A discontinuity that occurs when gas bubbles from the arc become trapped in the weld pool and leave small grooves along the surface of the weld bead after the slag solidifies. Gas marking, also called worm tracking, is more common with FCAW-G than FCAW-S.

gas metal arc welding

GMAW. An arc welding process in which a bare wire electrode and shielding gas are fed to the weld through a welding gun. Gas metal arc welding is also sometimes referred to as metal inert gas welding (MIG welding) or metal active gas welding (MAG welding), but these terms are non-standard in the United States.

gas nozzle

A device in a welding gun that forces shielding gas to surround the electrode and arc. The gas nozzle is placed directly over the contact tip and gas diffuser in a welding gun.

gas-shielded FCAW

FCAW-G. A type of FCAW that uses a flux-filled, tubular wire electrode and an external shielding gas to protect the weld area. Gas-shielded FCAW processes reduce the risk of weld cracking.

gas-shielded flux-cored arc welding

FCAW-G. A type of FCAW that uses a flux-filled, tubular wire electrode and an external shielding gas to protect the weld area. Gas-shielded flux-cored arc welding processes reduce the risk of weld cracking.

generator

A device that converts mechanical energy to electrical energy. Generators use mechanical devices like engines and motors to generate electricity.

goggles

A type of tight-fitting eye protection that completely covers the eyes, eye sockets, and surrounding facial area. Goggles offer protection from impact, dust, chips, and splashes.

green steel

Steel that is raw and untreated. Green steel rods and strips are used in the FCAW electrode fabrication process.

hand shield

A metal piece on an FCAW-S gun that protects the welder’s hand from the excessive amount of slag and spatter produced during FCAW-S. The hand shield is located over the trigger on the gun.

hardness

A material's ability to resist scratching, abrasion, indentation, or cutting. Hardness generally increases as ductility decreases.

heat treatment

A controlled heating or cooling process used to change the structure of a material. Heat treatment alters a material's physical and mechanical properties.

high-carbon steels

A carbon steel that contains 0.50-1.00% carbon. High-carbon steels are extremely strong and hard, but they always require heat treatment for effective welding.

horizontal

Welding that is performed on a fillet weld from the upper side of a horizontal surface and against a vertical surface. Horizontal welding on groove welds is performed on a horizontal plane with the weld face in a vertical plane.

hydrogen

H. A colorless, odorless gas that is the most abundant element on the planet. Hydrogen can cause weld metal to crack.

hydrogen cracking

A weld defect that occurs when weld metal absorbs too much hydrogen. Low-hydrogen electrodes reduce hydrogen cracking.

impact toughness

A material’s ability to absorb energy from a sudden, sharp blow without breaking or fracturing. Impact toughness is a key property because it determines the ability of a material to withstand sudden stresses.

input voltage

Electricity from an electrical distribution system that supplies power to electrical equipment. Input voltage for welding power sources is higher than the voltage used during arc welding.

insulated guides

A threaded copper part that is attached to the end of the main tube of some FCAW-S guns. Insulated guides protect the end of the gun from becoming electrically charged and help maintain proper electrode extension.

insulated nozzle

A type of gas nozzle with an integrated piece of non-conductive material that prevents it from becoming electrically charged. Insulated nozzles are more expensive than slip-on nozzles.

insulator

A non-conductive component that prevents the flow of electricity. Insulators are used to prevent certain parts of the FCAW gun from becoming electrically charged.

inverter

An electrical device that uses transistors to increase the frequency of supplied electricity and convert DC to AC. Inverters allow welding power sources to be smaller and more efficient.

inverter power source

A welding machine that uses a series of components including inverters and transistors to convert input electricity to usable power. Inverter power sources are small, portable, and energy-efficient, but expensive.

joining

A process that brings materials together. Joining methods include fastening, adhesive bonding, and welding.

kilopounds per square inch

ksi. A unit of pressure used in the US Customary System that is equal to thousands of pounds per square inch. The unit kilopounds per square inch is often used to measure the tensile strength of a weld.

knurled

A surface that has been marked with small diamond-shaped impressions. Knurled drive rolls are able to more easily grip FCAW electrodes without deforming them.

low-alloy steels

A steel that contains small amounts of intentionally added materials that change the properties of the metal. Low-alloy steels commonly include manganese, molybdenum, and nickel.

low-carbon steels

A carbon steel that contains 0.05-0.15% carbon. Low-carbon steels are generally tough, ductile, and easy to weld.

lubricant

A substance used to prevent friction between two surfaces in relative motion. Lubricants reduce resistance, wear, and heat.

manual process

A type of welding process in which the welder controls all welding variables. Shielded metal arc welding (SMAW) is an example of a manual process.

mechanical properties

A characteristic that describes how a material responds to forces that attempt to compress, stretch, bend, scratch, dent, or break it. Mechanical properties include tensile strength and ductility.

mechanical ventilation

A means of supplying fresh air to and removing hazardous fumes and gases from an area that uses a system of devices. Mechanical ventilation is required for many welding processes.

medium-carbon steels

A carbon steel that contains 0.30-0.50% carbon. Medium-carbon steels are strong, hard, and not as easy to weld as low-carbon steels.

melt-off rate

The rate at which metal melts off the electrode. The melt-off rate is measured in pounds per hour (lb./hr.) or kilograms per hour (kg/hr).

molybdenum

A hard, silvery-white metal that is strong and corrosion resistant. Molybdenum-based lubricant is applied to FCAW electrodes to prevent rust from forming on their surface.

negative

An electric charge with a surplus of electrons. A negative charge is often symbolized by a minus (-) sign.

oxygen

O. A colorless, odorless, tasteless gas that naturally exists in the atmosphere. Excessive oxygen can cause cracking, porosity, and rusting in welded metals.

particulate matter

A solid contaminant that consists of microscopic particles of metal, dirt, sand, or dust. The metal vapors created by welding condense into particulate matter that can be harmful if inhaled.

penetration

The depth to which the arc heat melts the joint below the surface of the base metals. Penetration is directly affected by the amount of amperage.

percent fill

The ratio of the weight of an electrode’s core compared to the electrode’s total weight. Percent fill can vary based on the materials included in the electrode’s core and their density.

personal protective equipment

PPE. Any clothing or device worn or used to minimize exposure to hazards and prevent injury. Personal protective equipment for welding usually includes a welding helmet, jacket, safety glasses, and gloves.

physical properties

A characteristic of a material that describes how it responds to environmental, electrical, magnetic, and thermal forces. Physical properties include corrosion resistance and conductivity.

polarity

Having two oppositely charged poles, one positive and one negative. Polarity determines the direction in which current flows.

porosity

A discontinuity characterized by the presence of tiny voids in a weld bead, which occurs when gas is trapped in the weld metal. Excessive porosity can weaken a weld.

positive

An electric charge with a shortage of electrons. A positive charge is often symbolized by a plus (+) sign.

pounds per square inch

psi. A unit of pressure used in the US Customary System. The unit pounds per square inch measures the amount of load pressure that is applied over an area of one square inch.

power source

The device that provides the electricity needed to perform arc welding. Power sources may also contain the wire feeder for the electrode.

pressure gauges

The device that indicates the amount of gas present in a gas cylinder. The pressure gauge detects the level of gas pressure and displays it on a dial.

pressure vessels

A container designed to hold liquids or gases at high pressures. Pressure vessels include gas cylinders and propane tanks.

radiation

Energy emitted in the form of particles or waves. Radiation exposure for prolonged periods of time can cause serious health problems.

ratio

The relationship between two quantities. Ratios can be expressed as a fraction or as two numbers separated by a colon.

reconditioned

Repaired or restored to the original condition. Welding electrodes can be reconditioned by heating them in a special oven at a specific temperature for a designated length of time.

rectifier

An electrical device that converts alternating current (AC) to direct current (DC). Rectifiers are sometimes used with transformers in welding power sources.

safety glasses

Protective eyewear with metal or plastic frames and impact-resistant lenses that may or may not offer vision correction. Many safety glasses also have protective side shields.

scavenging elements

A material that cleanses and purifies the weld pool while it is still in a molten condition. Scavenging elements can help improve the quality of the finished weld.

self-shielded FCAW

FCAW-S. A type of FCAW that relies on the flux materials within a tubular wire electrode to provide shielding for the weld area. Self-shielded FCAW processes do not require external shielding gas.

self-shielded flux-cored arc welding

FCAW-S. A type of FCAW that relies on the flux materials within a tubular wire electrode to provide shielding for the weld area. Self-shielded flux-cored arc welding processes do not require external shielding gas.

semi-automatic

A type of welding process in which the power source maintains a uniform arc and a wire feeder controls the electrode. In semi-automatic welding, the welder is responsible for controlling the position of the welding gun as well as the direction and speed of travel.

sheath

A case or covering that usually encloses a tubular structure. In FCAW electrodes, a metal sheath surrounds a flux core.

shielded metal arc welding

SMAW. An arc welding process that uses a flux-coated, stick-like consumable electrode. Shielded metal arc welding is also called stick welding or manual welding.

shielding

A substance that protects the weld pool and arc from reacting negatively with the atmosphere. Shielding can be provided by an external supply of gas or by a type of flux material.

shielding gas

A gas that protects the weld pool and arc from reacting negatively with the atmosphere. External shielding gas is supplied by a cylinder and flows through the welding gun.

single-pass welds

A weld that is formed by running a single weld bead. Single-pass welds often use stringer beads.

slag

A non-metallic byproduct of flux that floats to the top of the molten weld pool and forms a hardened layer on top of the solidified weld metal. Slag protects cooling metal and is then chipped off.

slag inclusions

A discontinuity that occurs when flux residue is trapped in the weld metal. Slag inclusions can affect the strength and integrity of a finished weld.

slip-on nozzle

A type of gas nozzle that consists of separate insulator and nozzle components. Slip-on nozzles are less expensive than insulated nozzles.

SMAW

Shielded metal arc welding. An arc welding process that uses a flux-coated, stick-like consumable electrode. SMAW is also called stick welding or manual welding.

spatter

Liquid metal droplets expelled from the welding process. Spatter can leave undesirable dots of metal on a workpiece surface.

spools

A cylindrical device used for storing, winding, and unwinding wires. Spools of electrode wire are used in semi-automatic and automatic welding processes.

spray arc transfer

A type of metal transfer in which the filler metal at the end of the electrode melts into small, fine droplets. Spray arc transfer creates a stable arc and little spatter.

stainless steels

A type of steel that contains 11-30% chromium and exhibits excellent hardness and corrosion resistance. Stainless steel can be welded with many different welding processes.

strength

The ability of a material to resist forces that attempt to break or deform it. A material exhibits tensile, compression, or shear strength, depending on the deforming force.

tensile strength

A material’s ability to resist forces that attempt to pull it apart or stretch it. Tensile strength of welds is usually expressed in kilopounds per square inch (ksi) or kilopascals (kPa).

terminals

A connecting point in a circuit where a conductor can be attached to connect a component. Terminals can be either positive or negative.

toughness

A material’s ability to absorb energy without breaking or fracturing. Toughness generally increases as hardness decreases.

transformer

An electrical device that uses mutual induction to transfer electrical energy from one circuit to another without changing the frequency. Transformers are used in welding power sources to provide a usable low-voltage, high-amperage current.

transformer power source

A welding machine that uses a large transformer to convert input electricity to usable power. Transformer power sources are relatively inexpensive but large and inefficient.

usability designator

A number or letter used to indicate an FCAW electrode’s operating requirements and characteristics in the AWS classification. Usability designator numbers range from 1-14, but 1, 9, and 12 are most common.

valve cap

A device used to protect the valves on a gas cylinder. Valve caps are an important safety device.

valves

A mechanical device that controls the flow of fluids such as liquid or gas. Valves contain movable parts that open, close, or obstruct one or more openings or passageways.

vaporizes

Changes from a solid or liquid to a gas. Some of the flux material at an FCAW electrode’s core vaporizes to create shielding and initiate fluxing reactions within the weld metal.

ventilation

A means of moving air to remove contaminants and provide clean air. Ventilation reduces the hazards posed by welding fumes and gases.

voltage

The electrical force or pressure that causes current to flow in a circuit. Voltage is measured in volts (V).

water-cooled guns

A type of welding gun that uses water as a coolant. Water-cooled guns require external equipment to deliver the water.

weld bead

The end product of a joint that has been welded. Weld beads are formed using a variety of different techniques.

weld pool

The small area of molten metal that forms during welding and that, when cooled, forms the permanent joint. The weld pool is sometimes called the weld puddle.

welder

A person who performs welding. Welders perform many arc welding processes.

welding

A joining process that permanently bonds two separate components together. Welding uses heat, pressure, or a combination to make one new part.

welding gun

A welding instrument that conducts electricity, guides the electrode, and, in some cases, releases shielding gas. Welding guns are used in some automatic and semi-automatic welding processes.

welding helmet

A heat-resistant head covering that consists of a hard face-guard and a dark-tinted filter plate. Welding helmets protect welders from flying debris and the intense ultraviolet light produced by the arc and may reduce exposure to welding fumes.

welding positions

The position in which a welder performs a weld. Welding positions include overhead, vertical, flat, and horizontal.

wire feed speed

WFS. The rate at which the wire electrode is fed through the welding gun. Wire feed speed determines amperage and the amount of heat in the arc.

wire feeder

The device that feeds a supply of wire electrode to the welding gun. Wire feeders are either built inside or set beside the power source.

wire feeder welder

A self-contained welding unit that houses both the power source and a constant-speed wire feeder. Wire feeder welders are economical and good for performing light-duty FCAW.

work cable

The path used in arc welding to conduct electricity from the power source to the workpiece. The work cable attaches to the workpiece via the work clamp.

work clamp

A component that connects the work cable to the workpiece. The work clamp helps form the welding circuit.

workpiece

A part that is being worked on during manufacturing. The workpiece may be subject to cutting, welding, forming, or other operations.

worm tracking

A discontinuity that occurs when gas bubbles from the arc become trapped in the weld pool and leave small grooves along the surface of the weld bead after the slag solidifies. Worm tracking, also called gas marking, is more common with FCAW-G than FCAW-S.