Overview of Weld Types 221

air carbon arc cutting

CAC-Air. A method of thermal cutting that uses the intense heat from a carbon arc to melt a metal workpiece. Air carbon arc cutting uses compressed air to remove the molten metal from the cut.

amperage

The amount of current flowing in a circuit. Amperage is measured in amperes (A), or amps.

arc length

The distance that electricity must travel from the tip of the electrode to the workpiece. Maintaining proper arc length is important for preventing weld defects.

arc welding

A joining process that uses an electric arc to melt 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).

autogenous welding

Welding that does not use filler metal and simply melts the base metals at the joint. Autogenous welding, also known as fusion welding, often creates weld joints that are stronger than the base metals.

back-gouging

Removing thin pieces of metal from a workpiece on the side opposite an initial weld. Back-gouging is typically used to allow complete joint penetration.

base metals

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.

bevel groove weld

A groove weld with one edge shaped like a V-groove weld and one edge that is square. Bevel-groove welds require less preparation and weld metal than V and U groove welds.

burnthrough

A discontinuity that occurs when weld metal from one side of a joint melts through to the other side. Burnthrough can leave an open hole in the joint, which must then be ground down and re-welded.

butt joint

A joint created between two parts that lie in the same plane. Butt joints are simple, common joints.

butting

Touching flush against another object with flat edges. Butting workpiece edges create joints like butt joints and corner joints.

CAC-Air

Air carbon arc cutting. A method of thermal cutting that uses the intense heat from a carbon arc to melt a metal workpiece. CAC-Air uses compressed air to remove the molten metal from the cut.

carbon

A common nonmetallic element that is combined with iron to create steel. Carbon may be left behind by material removal processes, and must be removed before welding.

chipping

Cutting or breaking small pieces, or chips, of material from a workpiece using an edged tool. Chipping is often used to prepare a joint for welding.

CJP

Complete joint penetration. A weld condition that occurs when weld metal extends throughout the full thickness of the base metals, completely filling the joint. Welds that require CJP and are welded from only one side of the joint may use weld backing.

complete joint penetration

CJP. A weld condition that occurs when weld metal extends throughout the full thickness of the base metals, completely filling the joint. Welds that require complete joint penetration and are welded from only one side of the joint may use weld backing.

concave

Curving inward like the interior surface of a bowl. A concave weld face often results from travel speeds or voltages that are too high.

convex

Curving outward like the exterior surface of a circle or sphere. Convex weld faces can be the result of low voltage or insufficient arc length.

cooling rates

The time required for weld metal and the heat-affected zone to lower in temperature and solidify. Cooling rates impact what electrodes are appropriate for certain welding applications.

corner joint

A joint created between the edges of two workpieces, often located at right angles to one another. Corner joints require large amounts of filler metal.

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.

discontinuities

An irregularity in the specified and expected composition of a weld. A discontinuity is not a defect if it does not exceed specifications.

distortion

Warpage or disfigurement in the base metal. Distortion occurs due to stresses caused by heating base metal to expansion and then cooling it to contraction.

double-groove weld

A weld made by creating two groove welds on either side of a joint. Double-groove welds are strong and often require less filler metal than single-groove welds.

double-groove welds

Groove welds that have been applied to both sides of a joint. Double-groove welds are often more effective than single-groove welds.

edge joint

A joint created between the aligned edges of two parallel parts. Edge joints, or parallel joints, are useful for joining plate metal workpieces.

electrical resistance

A force that opposes the flow of electrical current. Electrical resistance creates heat, which can be used for welding.

electrodes

Components in an electrical circuit that conduct electricity. A welding electrode can also act as filler metal.

excessive penetration

A weld discontinuity that occurs when too much heat is applied to the weld zone, causing the weld metal to fall through the joint. Excessive penetration includes burnthrough.

face reinforcement

Any weld metal on the weld face that extends beyond the surface of the base metal. Face reinforcement may be left or ground down to provide a smooth surface.

fast-fill electrodes

A consumable electrode that lays down a large amount of weld metal in a short amount of time. Fast-fill electrodes melt quickly and are ideal for large workpieces.

fast-freeze electrodes

A consumable electrode that solidifies quickly. Fast-freeze electrodes are ideal for overhead-position welding.

filler metal

Metal deposited into the weld that often adds strength and mass to the welded joint. In some welding processes, the electrode acts as the filler metal.

fillet welds

A triangular weld made to join two surfaces at right angles to each other. Fillet welds are the most common type of welds.

fill-freeze electrodes

A type of electrode that has both fast-fill and fast-freeze characteristics. Fill-freeze electrodes fill up a joint quickly and solidify quickly.

flat-position welding

Welding that is performed on the upper side of a joint. During flat-position welding, the face of the weld is horizontal.

gouging

Removing thin pieces of metal from a workpiece with a tool. Gouging is used to allow complete joint penetration or to prepare a surface for welding.

grinding

The use of an abrasive to wear away at the surface of a workpiece and change its shape. Grinding can be used to shape workpieces before welding or to remove undercut.

groove welds

A weld made in the opening between two parts that provides space to contain weld metal. Groove welds are used on all joints but are less common for lap joints.

heat-affected zone

HAZ. The area around a weld affected by the heat of the welding process. The heat-affected zone does not melt, but its mechanical properties are altered by the heat of welding.

horizontal-position welding

Welding with a horizontal axis that is performed on the upper side of a horizontal or vertical surface. Horizontal-position welding is often used for fillet and groove welds.

Incomplete fusion

A discontinuity that occurs when the weld metal and base metal or adjoining weld beads are not fully fused. Incomplete fusion significantly weakens the integrity of a weld.

Incomplete joint penetration

IJP. A discontinuity characterized by an unpenetrated and unmelted area in a joint that occurs when weld metal does not extend through the full thickness of the joint. Incomplete joint penetration can result from insufficient welding heat, improper joint design, and improper lateral control of the welding arc.

J-groove weld

A groove weld made in an opening shaped like the letter “J”. J-groove welds use one base metal with a square edge and one base metal with a concave edge.

joint

The meeting point of two materials that are fused together. Welding creates a permanent joint.

joint penetration

The depth to which weld metal extends into a joint. Joint penetration is directly affected by the amount of amperage, which determines arc heat.

joint preparation

Any process used to prepare base metals before welding. Joint preparation can involve cleaning, machining, grinding, or other operations.

joint type

The configuration in which two or more workpieces are joined. There are five basic joint types for welding: butt, corner, edge, lap, and T-joints.

lap joint

A joint created between the edge of one part and the surface of an overlapping parallel part. Lap joints provide more stress resistance than butt joints.

legs

The distance from the root of a fillet weld to the toe. Leg length determines the size of a fillet weld.

machining

Removing metal from a workpiece through the use of cutting tools. Machining is often used to remove excess weld metal from the surface of a completed part or to prepare joints.

mechanical properties

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 hardness and ductility.

out-of-position welding

Welding that takes place is any position besides the flat or horizontal position. Out-of-position welding includes welding in the vertical and overhead positions.

overhead-position welding

Welding that is performed from the underside of a joint. Overhead-position welding requires extra safety precautions.

overlap

A discontinuity that occurs when the weld metal protrudes beyond the weld toe or weld root. Overlap is nearly always unacceptable in a finished weld.

oxyfuel cutting

OFC. A thermal cutting process that uses a flame produced by a mix of oxygen and fuel gas to remove metal. Oxyfuel cutting is sometimes called flame cutting or gas cutting, but these terms are non-standard.

parallel

Extending in the same direction and equally distant from one another at all points. Parallel lines or objects never intersect.

parallel joint

A joint created between the aligned edges of two parallel parts. Parallel joints, or edge joints, are useful for joining plate metal workpieces.

partial joint penetration

PJP. A weld condition that occurs when the weld metal extends only part of the way through a joint. Partial joint penetration is intentionally less than complete to prevent melt through.

perpendicular

Intersecting at right angles to one another. Perpendicular lines create angles measuring exactly 90 degrees.

plane

An imaginary flat surface that extends infinitely in any direction in two dimensions. Components lying in the same plane are joined by butt joints.

plasma arc cutting

PAC. A thermal cutting process that uses plasma, which is a jet of ionized gas, to cut metal. Plasma arc cutting, or plasma cutting, is a quick process that creates high-quality cuts.

plug weld

A weld made in a circular hole in one part to join it to another part positioned directly beneath it. Multiple plug welds are usually required to form a strong joint.

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.

resistance welding

A welding process that joins parts using heat generated by resistance to the flow of electric current. Resistance welding also applies pressure to weld the parts together.

right angle

An angle that measures 90 degrees. Right angles are formed by perpendicular workpieces.

root face

The distance between the root and where the bevel of a joint begins. The root face helps with proper penetration and weld strength.

root opening

The separation between base metals at the root of a weld. The size of the root opening determines how much weld metal is needed to obtain fusion at the root.

root reinforcement

Weld metal applied to the root of a previously made weld. Root reinforcement can help improve weld strength.

seam weld

A continuous weld made on or between the surfaces of overlapping parts. Seam welds are often used for tanks and pipes.

single-groove welds

A groove weld applied to only one side of a joint. Single-groove welds generally require complete joint penetration.

slag

A nonmetallic byproduct of flux that floats to the top of the molten weld puddle 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 between two layers of weld metal. Slag inclusions can negatively affect the strength and integrity of a welded joint.

slot weld

A weld made in an elongated hole in one part to joint it to another part positioned directly beneath it. Slot welds are stronger than plug welds but require more filler metal.

spot weld

A small weld made on or between the surfaces of overlapping parts. Multiple spot welds are generally required to join parts.

square groove weld

A groove weld made in an opening between square workpiece edges. Square groove welds use base metals with straight edges that are slightly separated.

strength

The ability of a material to resist forces that would otherwise break or deform it. There are different types of strength, including tensile, compressive, and shear strength.

tensile strength

A material's ability to resist forces that attempt to pull it apart or stretch it. Materials with high tensile strength tend to deform, bend, or stretch before breaking.

thermal cutting

A group of cutting processes that use heat to remove metal from a workpiece. Thermal cutting processes include oxyfuel, air carbon arc, plasma arc, and laser beam cutting.

T-joint

A joint created between the edge of one part and the surface of a second, perpendicular part that resembles the letter “T”. T-joints are very common joints that are simple to create.

travel speed

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).

U-groove weld

A groove weld made in an opening shaped like the letter “U”. U-groove welds use base metals with concave edges.

undercut

A groove melted into the base metal at the weld toe or root that is left unfilled by weld metal. Undercut concentrates stress on the weld and can weaken it.

underfill

A depression on the weld face or root surface that extends below the surface of the adjacent base metal. Underfill occurs when a welder fails to properly fill a joint with metal and can be corrected by making another welding pass.

vertical-position welding

Welding that is performed on a vertical surface using an upward or downward motion. Vertical-position welding is more difficult than flat- or horizontal-position welding.

V-groove weld

A groove weld made in an opening shaped like the letter “V”. V-groove welds use base metals with angled edges.

voltage

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

weld axis

An imaginary line that runs through the center of a weld from one end to another. The weld axis is located at the geometric center of the weld's cross section and is parallel with the workpiece's surface.

weld backing

A strip of metal located on the side of a joint opposite the weld that provides a surface for depositing the first layer of metal and prevents molten metal from escaping through the joint. Weld backing can also be used to protect the back of the weld from atmospheric contamination.

weld beads

The end product of a joint that has been welded. Weld beads can be flat, convex, or concave in shape.

weld face

The exposed surface of a weld. The weld face may be convex, concave, or flush with the workpiece.

weld metal

The portion of a weld that has been melted during welding. Weld metal may consist of base metal only or a combination of base metal and filler metal.

weld puddle

The small area of molten metal that forms during welding. The cooled weld puddle forms the permanent joint.

weld root

The point at which a weld intersects the surfaces of the base metals opposite the face of the weld. Some welds have openings located at the weld root.

weld throat

The distance between the weld root and weld face at the center of the weld. The weld throat determines a weld's size and strength.

weld toes

The point at which a weld's face meets the base metal. Weld toes can experience cracking and undercut.

welding

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

welding positions

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

welding procedure specification

WPS. A written document that contains all the specific information necessary for completing a weld. A welding procedure specification must be approved and tested before it can be used.