FCAW Applications 321
FCAW Applications provides a comprehensive overview of how to perform FCAW processes. Before beginning FCAW, it is important to prepare the joint and select the appropriate electrode. During FCAW, the welder controls the electrode's orientation and travel speed. Welders must also be aware of many FCAW-specific variables, such as amperage, voltage, and shielding gas, as well as the effects of such variables. Understanding variables helps prevent FCAW weld discontinuities and defects, such as excessive spatter, porosity, and slag inclusion.
After taking this class, users will be familiar with many of the considerations and variables that go into using FCAW processes, which is essential to producing quality welds and avoiding weld discontinuities and defects. The ability to recognize and avoid common welding issues reduces scrapped parts and increases quality.
Number of Lessons 27
- FCAW: Overview
- Choosing FCAW
- Electrode Selection
- Electrode Selection: Metal Properties
- Review: FCAW Basics
- Joint Design
- Joint Preparation
- Electrode Orientation: Work Angle
- Electrode Orientation: Travel Angle
- Electrode Orientation: Techniques
- Electrode Orientation: In Action
- Review: FCAW Preparation
- Starting the Arc
- Running Bead: Electrode Extension
- Running a Bead
- Running a Bead: In Action
- Review: FCAW Process
- Variables: Amperage and Wire Feed Speed
- Variables: Output Type
- Variables: Contact Tip to Work Distance
- Variables: Heat Input
- Variables: Shielding Gas and Gas Flow
- Review: FCAW Variables
- Troubleshooting: FCAW Discontinuities
- Troubleshooting: FCAW Discontinuities and Defects
- Troubleshooting: Arc Blow
- Review: FCAW Troubleshooting
- Describe FCAW processes.
- Identify the factors to consider when choosing an FCAW process.
- Describe various factors that affect FCAW electrode selection.
- Identify important metal properties to consider when choosing FCAW electrodes.
- Describe joint design for FCAW.
- Describe joint preparation for FCAW.
- Describe the work angle for FCAW processes.
- Describe the travel angle for FCAW processes.
- Distinguish between backhand and forehand techniques.
- Distinguish between backhand and forehand techniques.
- Describe important aspects of starting the arc in FCAW.
- Describe electrical extension for FCAW processes.
- Describe the effects of travel speed on running FCAW beads. Describe the characteristics of FCAW beads.
- Describe the characteristics of FCAW beads.
- Describe the relationship between amperage and wire feed speed in FCAW.
- Describe the ways in which output type affects FCAW processes.
- Describe the way in which contact tip to work distance affects FCAW processes.
- Describe the ways in which input heat affects FCAW processes.
- Describe the ways in which shielding gas and gas flow affect FCAW-G.
- Describe common FCAW welding discontinuities.
- Identify common FCAW welding discontinuities and defects.
- Describe arc blow.
A gas that reacts with other elements. Active gases used in welding processes include carbon dioxide and oxygen-gas mixtures.
An angle that measures between 0 and 90 degrees. Examples of acute angles in welding include travel angles and most work angles.
A material that is intentionally added to a material in order to change its properties. Alloying elements can improve the strength, ductility, hardness, and toughness of a finished weld.
A silvery white metal that is soft, light, and an effective conductor. Aluminum is often one of the main deoxidizers in flux material.
American Welding Society
AWS. The non-profit organization that regulates the industrial standards for welding. AWS also promotes the welding industry in the United States.
A measurement of current. FCAW amperage is determined by the speed in which the electrode is fed through the welding gun.
A shielding gas mixture composed of argon and carbon dioxide. Ar/CO2 mixtures are the most commonly used shielding gases in FCAW processes.
The area in which electricity jumps from the electrode to the workpiece. Arcs generate heat that melt the base metals and filler metal during welding processes.
A condition resulting from the interaction of an electric current and the magnetic field the current induces. Arc blow can cause several weld discontinuities, including excessive spatter, incomplete fusion, and porosity.
The distance that the electricity must travel from the tip of the electrode to the weld puddle. Longer arcs require more voltage.
The process of controlling a welding arc in an even and predictable manner. Arc stability is essential during the welding process.
Elements and materials included in the core of FCAW electrodes that prevent them from becoming erratic and difficult to control. Arc stabilizers used in FCAW electrodes include potassium and sodium.
Ar. An inert gas commonly mixed with carbon dioxide for use as a shielding gas. Argon is much heavier than air, so it effectively shields the weld area, especially when used in the flat position.
Moving the electrode along the workpiece when it is pointing opposite the direction of travel. The backhand technique is often used with self-shielded FCAW.
The angle formed between the prepared edge of one side of the base metal and a plane perpendicular to the surface of the other side of the base metal. In FCAW, the size of the bevel angle depends on the type of FCAW method.
A weld defect that occurs when too much heat is applied to the weld zone, causing the base material to fall through the joint as well as excess penetration. Burn-through is also called excessive penetration.
CO2. An active gas commonly used as shielding for FCAW. Carbon dioxide is inexpensive but yields a violent arc.
CO2. An active gas that is heavy, colorless, and odorless. Carbon dioxide is commonly used as a shielding gas.
CO. A colorless, odorless, poisonous gas made of carbon and oxygen. Carbon monoxide is produced when carbon dioxide is heated to high temperatures and dissociates.
A common metal that is an alloy of iron and carbon. The amount of carbon in a carbon steel affects its strength, ductility, and malleability.
The type, amount, and arrangement of atoms that, combined, compose a whole material or substance. Chemical composition can be altered whenever a change occurs at the atomic level.
The act of cutting or breaking small pieces, or chips, with an edged tool. Chipping is sometimes used to remove slag and spatter from welded workpieces.
A shiny, hard, steel-gray metal that improves corrosion resistance. Chromium is sometimes present in flux materials to improve creep resistance, hardness, and strength in the weld.
A completely enclosed path that contains an electrical current. In welding, a circuit is also known as a welding circuit.
Carbon dioxide. An active gas commonly used as shielding for FCAW. CO2 is inexpensive but yields a violent arc.
Able to act as a path for the movement of electricity. Conductive materials include many different types of metals.
CV. An amount of electricity from a welding power source that varies only slightly. With constant voltage, the current, or amperage, changes significantly.
An electrode that conducts electricity to the arc but also melts into the weld as a filler metal. Some consumable electrodes may also provide shielding that protects the arc and weld puddle.
The device located inside the welding gun that conducts electricity to the electrode and directs the wire electrode into the weld joint. Contact tips are usually made of copper.
contact tip to work distance
CTWD. The distance from the contact tip to the workpiece surface. As contact tip to work distance increases, the welding current decreases.
Curving outward like the exterior surface of a circle or sphere. An overly convex weld is often considered a discontinuity or defect as determined by welding code.
Curving outward like the exterior surface of a circle or sphere. In FCAW, overly convex weld beads can be produced as a result of using too much amperage.
The inner part of an electrode that is surrounded by an outer sheath. The core of FCAW electrodes contains flux materials.
A process by which a metal gradually degrades or wears away. Corrosion typically occurs when metal is exposed to atmosphere, moisture, or other substances.
The ability of a material to resist deterioration and chemical breakdown due to surface exposure in a particular environment. Corrosion resistance is an important physical property of finished welds.
A depression that forms in the weld bead. A crater can cause cracking if it is not properly filled.
A gap or break in the surface of a weld that occurs because welding was improperly terminated. Crater cracks are also called star cracks.
The ability of a metal to withstand a constant force or weight at elevated temperatures without deforming. Creep resistance is also called creep strength.
Contact tip to work distance. The distance from the contact tip to the workpiece surface. As contact tip to work distance increases, the welding current decreases.
The rate and amount of electrical flow, which is measured in amperage. A continuous current is required in arc welding in order to maintain the electric arc.
Constant voltage. An amount of electricity from a welding power source that varies only slightly. With constant voltage, the current, or amperage, changes significantly.
To break down or separate into smaller parts. When used in FCAW-G, carbon dioxide decomposes and reacts with the flux materials at the core of an FCAW electrode.
An irregularity in a weld that exceeds the part design tolerances. A defect is a rejectable discontinuity, which is determined by welding code.
A material that removes nitrogen from the molten weld puddle and arc. Denitrifiers prevent nitrogen from ruining a weld bead.
A material that removes oxygen from the molten weld puddle and arc. Deoxidizers prevent oxygen from ruining a weld bead.
The rate at which an electrode melts into the molten weld puddle to form a weld. The deposition rate can be measured in pounds per hour or in grams per minute.
DC. Current that flows continuously in one direction. Direct current is required in several common arc welding processes.
direct current electrode negative
DCEN (DC-). The arrangement of direct current arc welding cables and leads in which the electrode is the negative pole and the workpiece is the positive pole of the welding arc. Direct current electrode negative is sometimes called straight polarity.
direct current electrode positive
DCEP (DC+). The arrangement of direct current arc welding cables and leads in which the electrode is the positive pole and the workpiece is the negative pole of the welding arc. Direct current electrode positive is sometimes called reverse polarity.
Steel workpieces that have surface contaminants. Dirty steel includes workpieces with rusted surfaces.
An irregularity in the specified and expected composition of a weld. A discontinuity is not always a defect.
A process that separates a chemical combination into smaller, separate parts. An example of dissociation includes carbon dioxide separating into carbon monoxide and oxygen.
A travel angle that points the electrode opposite the direction of travel. Drag angles are used with the backhand technique.
A travel angle that points the electrode opposite the direction of welding. Drag angles are used with the backhand technique.
The distance from the end of the contact tip to the end of the electrode. Electrical stickout is also called electrode extension.
An imaginary line that runs through the center of the length of an electrode. The electrode axis is perpendicular to and at the geometric center of its cross section.
A measurement of the thickness of the electrode. Electrode diameter can affect productivity.
The distance from the end of the contact tip to the end of the electrode. Electrode extension is also called electrical stickout.
The position in which a welder manipulates the electrode. Electrode orientation refers to both the work angle and the travel angle.
The factors that make up the surroundings in a given place. An environment consists of various components, including noise, moisture, temperature, and air quality.
A weld defect that occurs when too much heat is applied to the weld zone, causing an excess in penetration and the base material to fall through the joint. Excessive penetration is also called burn-through.
Flux-cored arc welding. An arc welding process that uses a continuously fed consumable electrode with a flux core wrapped within an outer metal sheath. FCAW can be a semi-automatic or automatic process.
Gas-shielded flux-cored arc welding. An FCAW process that uses fluxing agents and an external shielding gas to shield the weld. FCAW-G provides the weld area with double shielding protection.
Self-shielded flux-cored arc welding. An FCAW process that uses only the fluxing agents contained in the electrode to shield the weld. FCAW-S processes do not need external shielding gas.
A metal that contains iron. Ferrous metals are the most common type of welded metal.
Performing a weld on a job site and not in a welding facility. Field welding typically occurs outdoors.
A type of weld that is triangular in shape and joins two surfaces at right angles to each other in a lap joint, T-joint, or corner joint. Fillet welds are the most common types of welds.
A welding position used to weld from the upper side of the joint. Some FCAW electrodes are designated for only the flat or horizontal weld positions.
The rate at which shielding gas moves from its cylinder, through the gas delivery system, and to the arc and weld puddle. Flow rate is usually measured in standard cubic feet per hour (SCFH) or in liters per minute (l/min).
Non-metallic materials used to protect the weld puddle and solid metal from atmospheric contamination. In FCAW, flux material is contained in the core of the electrode.
flux-cored arc welding
FCAW. An arc welding process that uses a continuously fed consumable electrode with a flux core wrapped within an outer metal sheath. FCAW can be a semi-automatic or automatic process.
Moving the electrode along the workpiece when it is pointing in the direction of travel. The forehand technique is sometimes utilizes during out-of-position FCAW processes.
A gas-shielded FCAW weld discontinuity that occurs when a gas bubble from the arc becomes trapped in the weld puddle and marks the weld bead after the slag solidifies. Gas marks are also called worm tracking.
A gas-shielded FCAW weld discontinuity that occurs when a gas bubble from the arc becomes trapped in the weld puddle and marks the weld bead after the slag solidifies. Gas marks are also called worm tracking.
A combination of gases used for shielding a weld. The most common gas mixture used in FCAW is an argon-carbon dioxide (Ar/CO2) mixture.
FCAW-G. An FCAW process that uses fluxing agents and an external shielding gas to shield the weld. FCAW-G provides the weld area with double shielding protection.
A standard of measure used to determine a specific thickness of sheet metal. The larger the gauge number is, the thinner the metal is.
globular arc transfer
A type of metal transfer in which the electrode produces a large ball of metal when it touches the workpiece. Globular arc transfer deposits large amounts of metal into the weld puddle but can produce a lot of spatter due to its erratic nature.
The use of an abrasive to wear away at the surface of a workpiece and change its shape. Grinding may be used as a means of removing spatter and finishing a weld.
The angle of the groove between two workpieces that are welded together. In FCAW, the groove angle depends on the type of FCAW method used.
A type of weld that consists of an opening between two part surfaces, which provides space to contain weld metal. Groove welds are used for many different joints as determined according to AWS welding code and/or welding procedure specifications.
The angle, either acute or right, that is between the electrode axis and a line perpendicular to the weld axis. The gun angle, which is sometimes called the work angle, positions the weld bead on the joint and determines the direction in which the heat is applied.
The ability of a material to resist scratching, abrasion, indentation, or cutting. Hardness is one of the mechanical properties of a given material.
HI. The amount of thermal energy provided to the workpiece during the welding process. Heat input is measured in kilojoules per inch (kJ/in.) or kilojoules per millimeter (kJ/mm).
A common welding position used for fillet and groove welds when the workpiece is parallel to the work surface. Some FCAW electrodes are designated for only the flat or horizontal weld positions.
The formation of fractures that develop in a weld after its solidification is complete. Hot cracking is also called solidification cracking.
The lack of complete integration between the weld metal and adjoining weld beads. Incomplete fusion can be caused by faulty operator technique, improper preparation of the base metal, insufficient welding heat, lack of access to the adjoining beads, and improper joint design.
A discontinuity characterized by an unpenetrated and unfused area in a joint. Incomplete penetration occurs when weld metal does not extend through the thickness of the joint.
A type of gas that is inactive and has a limited ability to form chemical reactions. Inert gases, such as argon and helium, are often used as shielding gases.
A small, non-conductive piece of material, such as plastic or fiberglass, that is placed inside a welding gun to prevent the gun from becoming electrically charged. Insulated guides also allow for longer electrical stickout and help to reduce weld defects such as porosity.
The temperature of the base metal between the first and last welding pass. The interpass temperature must never fall below the preheat temperature.
An association in which the value of one variable increases while the value of the other variable decreases. An inverse relationship is also called a negative relationship.
A charged atom or molecule. An ion can be either positive or negative depending on whether it has a shortage or surplus of electrons.
Inches per minute. In the English system, the number of linear inches that a component travels in one minute. In welding, inches per minute is used to measure many variables, including travel speed and wire feed speed.
The specification of a particular joint type and its required dimensions. Joint design depends on the welding process and the base metal's thickness.
The creation of the appropriate opening for a weld before welding takes place. Joint preparation covers a variety of processes, including cutting, cleaning, and preheating.
kilojoules per inch
kJ/in. The amount of energy that travels through a component for the length of one linear inch. In welding, kilojoules per inch is often used to measure heat input.
kilojoules per millimeter
kJ/mm. The amount of energy that travels through a component for the length of one linear millimeter. In welding, kilojoules per millimeter is often used to measure heat input.
A heavy, gray metal that is very soft and ductile, a poor conductor of electricity, and can be added to steel to improve machinability. Lead in base metal can cause hot cracking in FCAW welds.
The distance from the root to the toe of the fillet weld. Leg length determines the size of a fillet weld.
A steel that contains small amounts of intentionally added materials that change the properties of the metal. Most low-alloy steels include common alloying elements, such as manganese, molybdenum, and nickel.
A force of attraction that surrounds magnets and current-carrying conductors. In welding, unbalanced magnetic fields near the arc can cause arc blow.
A characteristic that describes how a material reacts when subjected to a force that attempts to stretch, compress, bend, dent, scratch or break it. Mechanical properties include strength, toughness, ductility, and hardness.
A measurement of the amount of filler metal deposited into a weld joint. The melt-off rate is measured in pounds per hour or grams per minute.
An electrical charge with a surplus of electrons. A negative charge is symbolized by a minus (-) sign.
A hard, malleable, silvery white metal often present in flux materials. Nickel increases a weld's strength and corrosion resistance.
To move back and forth from side-to-side. Oscillating an electrode from side-to-side along a joint will create a weave bead.
All welding positions outside of flat and horizontal positions. Out-of-position welding includes vertical and overhead positions.
The type of power that the power source produces. Forms of output include direct current, alternating current, constant current, and constant voltage.
O₂. A colorless, odorless, tasteless gas that naturally exists in the atmosphere. In welding, too much oxygen causes cracking and rusting in the metals.
The depth to which the arc heat can melt the joint below the surface of the base metal. Penetration is directly affected by the amount of amperage.
An intersection of two lines or objects at right angles to one another. Perpendicular lines create angles measuring exactly 90 degrees.
A characteristic of a material that describes the way it responds to forces other than mechanical ones. Physical properties include a metal's magnetic, thermal, and electrical attributes.
An imaginary surface that is perfectly flat or level. A plane is represented by a closed four-sided figure.
Having two oppositely charged poles, one positive and one negative. Polarity determines the direction in which current tends to flow.
A welding discontinuity which results from trapped gases in a material and is characterized by the appearance of tiny voids or bubbles on a weld bead. Excessive porosity can weaken a weld.
A welding discontinuity, which results from trapped gases in a material, that is characterized by the appearance of tiny voids or bubbles on a weld bead. Excessive porosity can weaken a weld.
An electrical charge with a shortage of electrons. A positive charge is symbolized by a plus (+) sign.
A device that provides electricity to the arc welding process. Arc welding power sources can be plugged into a wall outlet, or they can generate electricity through the use of a mechanical device like a motor and generator.
A specific temperature to which the base material is heated prior to welding. Preheat temperature is often specified in welding codes.
The application of heat to a base metal immediately before welding. Preheating provides several benefits to the welding process, such as reducing hardness, improving ductility, and lessening the chance of hydrogen cracks.
A travel angle that points the electrode in the direction of travel. Push angles are used with the forehand technique.
To undergo change when exposed to another substance. In welding, active gases will react when exposed to certain elements.
The force that opposes the flow of electrical current. Resistance also affects voltage.
An angle that measures exactly 90 degrees. Right angles are formed by two lines that are perpendicular to one another.
The separation at the joint root between the base metals, and where fusion should occur between the weld metal and adjoining weld beads. The size of the root opening determines how much weld metal is needed to obtain fusion at the root.
A weld bead that is more convex than allowed by welding code. Ropey weld beads are caused by excessive reinforcement and have a rope-like appearance.
FCAW-S. An FCAW process that uses only the fluxing agents contained in the electrode to shield the weld. FCAW-S processes do not need external shielding gas.
A case or covering that usually encloses a tubular structure. In FCAW electrodes, a metal sheath surrounds a flux core.
To protect the weld puddle and arc from reacting negatively with the atmosphere. A shield can be provided by either a gas or a type of flux.
An inert or slightly active gas that protects the weld puddle and arc from reacting negatively with the atmosphere. Shielding gases are used in some arc welding processes.
Cooled flux that forms on top of the weld bead. Slag protects cooling metal and is then chipped off.
A welding discontinuity resulting from the combined dissolution of flux and nonmetallic impurities. Slag inclusion can affect the strength and integrity of a weld in its final application.
A welding discontinuity resulting from slag becoming trapped in weld metal. Slag inclusion can affect the strength and integrity of a weld in its final application.
The formation of fractures that develop in a weld after its solidification is complete. Solidification cracking is also called hot cracking.
Liquid metal droplets expelled during the welding process. Spatter can leave undesirable dots of metal on a workpiece surface.
A type of steel that contains a minimum of 10.5% chromium. Stainless steel is very hard and exhibits excellent corrosion resistance.
A type of weld bead formed by moving the electrode straight along the joint. A quality stringer bead has good wash-in at the toes of the weld.
The construction of large structures such as buildings and bridges. Structural fabrication projects are heavily regulated, subject to a variety of tests, and required to meet very strict codes and standards.
A non-metallic element occurring naturally in large quantities, which is generally melted out or reduced by purification in the steel-making process. Sulfur in base metals can cause hot cracking in FCAW welds.
A material's ability to resist forces that attempt to pull apart or stretch it. Tensile strength is usually expressed in pounds per square inch or in Newtons per square meter.
Energy resulting from the motion of particles. Thermal energy is a form of energy that is transferred as heat.
The acute angle between the electrode axis and a line vertically perpendicular to the weld axis. The travel angle points the electrode either in toward or away from the direction of welding.
TS. The rate at which the welder moves the electrode along the joint to make the weld. Travel speed determines the size of the weld bead and is measured in inches per minute (in./min or ipm) or millimeters per minute (mm/min).
A lever on the welding gun that controls an electrical switch. When a welder holds the gun above the workpiece and pulls the trigger, the welding process begins.
A groove melted into the base metal at the weld toe or root that is left unfilled by weld metal. Undercut, which is often considered a defect, concentrates stress on the weld and weakens it.
A groove melted into the base metal at the weld toe or weld root that is left unfilled by weld metal. An undercut concentrates stresses on the weld and is considered a defect if it exceeds the part's tolerances.
An effect that occurs when air is sucked into the flow of shielding gas and the welding arc. The venturi effect is caused by an excessively high gas flow that hits and bounces off of a workpiece at a high velocity, which causes the gas to start moving in a swirling, whirlpool-like motion.
The distance between the end of the insulated guide and the end of the electrode. Visible stickout is the portion of the electrode that the welder can see.
The electrical force or pressure that causes current to flow in a circuit. Voltage is measured in volts.
The loss of voltage as an electric current moves through an electrical circuit. In FCAW, voltage drop can be reduced by increasing the electrode extension.
The section of deposited weld metal that aligns evenly with the weld toe. A good wash-in is smooth and even along the joint and does not undercut the base metal.
A weld bead formed by moving the electrode back and forth along the joint in a weaving motion. With a weave bead, the welder must first move the electrode in a triangular motion along the joint during the initial weld pass.
An imaginary line through the center and along the length of a weld. The weld axis is located at the geometric center of its cross section and is horizontal with the workpiece's surface.
A disfigurement or warping in the weld bead that signals improper welding preparation or procedure. Weld distortion is better controlled when using a colder welding arc and weld bead.
One progression of welding along a joint. The result of a weld pass is a weld bead.
The small area of molten metal that forms during welding, and which, when cooled, forms the permanent joint. Weld pools are also sometimes called weld puddles.
The point at which the weld face and the base metal meet. Weld toes can experience cracking and undercut.
A collection of laws or standards that outline practices for a particular welding application. Welding codes ensure safe welding practices and high-quality welded products.
The position in which the welder performs a weld. The different welding positions include overhead-, vertical-, flat-, and horizontal-position welding.
Welding Procedure Specification
WPS. A written document that contains all the necessary and specific information regarding the application of a welding project. Welding Procedure Specifications must be approved and tested before they can be used.
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 in FCAW.
The angle, either acute or right, that is between the electrode axis and the horizontal plane of the workpiece surface. The work angle, which is sometimes called the gun angle, positions the weld bead on the joint and determines the direction in which the heat is applied.
The component that, along with the electrode, comes in direct contact with the workpiece during welding. The work clamp is connected to the power source by the work cable and provides ground for the FCAW circuit.
A gas-shielded FCAW weld discontinuity that occurs when a gas bubble from the arc becomes trapped in the weld puddle and marks the weld bead after the slag solidifies. Worm tracking is also called gas marking.
The ability of a metal to tolerate gradual progressive force without permanent deformation. The yield strength of a weld should match the yield strength of its base metal.