Overview of Weld Defects 222

acute

An angle that measures less than 90 degrees. Acute angles are not acceptable for weld reentrant angles.

aluminum

A lightweight, highly conductive, silvery metal. Aluminum has good weldability, but certain factors, such as its melting point, can make the process difficult.

American Welding Society

AWS. A professional organization that supports the welding industry and promotes welding and related processes in the United States. The American Welding Society provides industry-standard codes and certification procedures.

amperage

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

arc gouging

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

arc length

The distance that electricity must travel from the tip of the electrode to the weld pool. Arc length is determined by voltage.

arc strikes

A welding discontinuity that appears as small, raised circles, lines, or burnt areas on the workpiece. Arc strikes occur when the arc is initiated outside the weld area.

back-gouging

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

backstep welding

A welding technique in which small welds are made in the opposite direction from the general direction of the weld. Backstep welding helps minimize distortion.

bridge cam gauges

A weld gauge designed to inspect the leg length and throat size of fillet welds, the reinforcement of groove welds, and other features. A bridge cam gauge can also inspect undercut, porosity, misalignment, and angle of preparation.

brittle

Unwilling to be drawn, stretched, or formed. Brittle materials tend to fracture when subjected to these forces.

burnthrough

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

butt joints

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

calipers

A measuring instrument that includes one or more sets of jaws and a scale marked with unit divisions. Calipers often include one set of jaws to measure outer diameters and another set of jaws to measure internal diameters.

centerline cracks

A longitudinal crack in the middle of a weld at the weld face. A centerline crack is a type of longitudinal crack caused by Improper width-to-depth ratio, improper welding techniques, and insufficient preheating.

Certified Welding Inspector

A person certified by the American Welding Society to perform visual and some destructive inspections on welds. Certified Welding Inspectors must be able to identify possible welding discontinuities and defects, use measuring instruments, and monitor any repairs.

Charpy V-notch test

A destructive testing method that involves cutting a small slot in the surface of a material and breaking the material across the slot using a weighted pendulum. Charpy V-notch testing allows inspectors to not only measure the strength of a weld but also examine it for internal defects.

chipping hammer

A steel tool with a flat chisel on one end and a conical chisel or point on the other. Chipping hammers are used to remove slag and spatter after welding.

clamps

A workholding device that grips and holds a workpiece in place. Clamps can be used when welding to prevent joint misalignment and distortion.

cold crack

A crack that forms after the weld metal cools. Cold cracks, including toe cracks, form as a result of stress and the presence of hydrogen in the metal.

consumables

Any material that is used up during a welding process. Common welding consumables include electrodes and filler metal, which become part of the weld.

contact tip to work distance

CTWD. The distance from the contact tip of the welding gun to the workpiece surface. Contact tip to work distance combines electrode extension and arc length.

contaminants

Any element or substance not original to a weld that may impact the quality and strength of a finished weld. Contaminants in welds include oxygen and nitrogen.

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.

crater cracks

A small crack in the center of a crater or depression in a weld face. Crater cracks can be prevented by filling in any craters or using a backstep technique when terminating the weld.

cross section

The physical or theoretical representation of the shape of a weld and the HAZ at the front of the weld. The cross section of a weld can be exposed by cutting or breaking a weld, which is done in various testing methods.

CTWD

Contact tip to work distance. The distance from the contact tip of the welding gun to the workpiece surface. CTWD combines electrode extension and arc length.

data

Any type of information gathered about a product or process. Data is often in the form of values or numbers.

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.

destructive testing

DT. A testing method that damages or destroys the workpiece being tested. Destructive testing is ideal for determining the strength of a weld.

developer

A substance that helps to draw penetrant to the surface of a part during liquid penetrant inspection. Developer makes the flaws in a part visible through capillary action.

digital analysis software

A computer program that simplifies and automates the collection and organization of data. Digital analysis software can help technicians interpret the results of ultrasonic weld inspection.

direction of travel

The direction in which welding occurs. The travel angle determines whether the electrode points towards the direction of travel or away from it.

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 of the base metal. Distortion occurs due to the stresses caused by the expansion and contraction of metal when it is heated and cooled.

DT

Destructive testing. A testing method that damages or destroys the workpiece being tested. DT is ideal for determining the strength of a weld.

ductility

A material's ability to be drawn, stretched, or formed without breaking. Ductility is more common in softer metals.

eddy current testing

ECT. A nondestructive testing method that uses electromagnetic induction to locate surface and near-surface discontinuities and defects. Eddy current testing is limited to use on electrically conductive materials.

electric current

The flow or movement of charged particles. Electric current is used in electromagnetic weld testing.

electrode

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

electromagnet

A magnet that exerts the forces of attraction and repulsion only when energized by electric current. An electromagnet is typically formed by wrapping wire around an iron core.

electromagnetic testing

ET. A nondestructive testing method that uses an electric current or magnetic field to determine if a weld is defective. Electromagnetic testing can reveal internal defects in a weld.

excessive face reinforcement

The use of more weld metal than is required to fill a weld joint. Excessive face reinforcement is not often considered a defect, but it wastes weld metal and welding time.

excessive root penetration

A discontinuity that occurs when the weld metal from one side of a joint extends through to the other side. Excessive root penetration can be caused by large openings, slow movement, or excessive amperage.

excessive root reinforcement

A measurement of how much weld metal extends through the root of a joint. Excessive root reinforcement is a result of excessive root penetration.

excessive spatter

A welding discontinuity in which small particles of molten metal are expelled outside of the weld and onto the workpiece. Excessive spatter does not often affect weld strength but can weaken coatings and hide other defects.

fabrication drawings

The welding design that shows the dimensions, materials, and welding information, including welding symbols and codes, needed to construct a structure. Fabrication drawings help welders meet weld requirements and identify and avoid weld defects.

FCAW

Flux-cored arc welding. An 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).

ferromagnetic

A type of material that is highly attracted to magnets and can become permanently magnetized. Ferromagnetic materials include iron and nickel.

fillet weld break test

A destructive test that involves breaking one side of a fillet weld sample. Fillet weld break tests can provide useful weld quality information to the inspector.

fillet weld gauge blades

A weld gauge designed to determine whether or not a fillet weld is within specified tolerances. Fillet weld gauge blades are used to check a weld's leg length and throat size.

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.

fit-up issue

A problem occurring when components are not properly positioned and aligned before welding. Fit-up issues, such as joint misalignment, can be prevented by clamping and holding workpieces in place during welding.

flux

A material that is intended to protect the weld pool and solid metal from atmospheric contamination. Flux is often a part of an electrode.

flux-cored arc welding

FCAW. An 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).

frequency

A measurement of the number of times a waveform repeats in one second. Frequency is measured in Hertz (Hz).

galvanized

Coated with zinc. Galvanized steel has better corrosion resistance than regular steel.

gas cylinder

A metal container that stores gases. Gas cylinders are built specifically for each gas and have different properties depending on the gas.

gas marks

A discontinuity in which gas bubbles from the arc become trapped in the weld pool and leave small grooves along the surface. Gas marks, also known as worm tracks, form when slag solidifies and a trapped gas bubble marks the weld bead.

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 releases more gases but less fumes than other arc welding processes.

gas tungsten arc welding

GTAW. A precise arc welding process that uses a non-consumable tungsten electrode and inert shielding gas. Gas tungsten arc welding is also known as tungsten inert gas welding (TIG welding).

gauges

A device that determines whether or not a part feature is within specified limits. Most gages do not provide an actual measurement value.

girder

A steel or iron beam used as part of the support structure for a large building. Girder welds are subject to rigorous inspection.

GMAW

Gas metal arc welding. An arc welding process in which a bare wire electrode and shielding gas are fed to the weld through a welding gun. GMAW releases more gases but less fumes than other arc welding processes.

gouging

Removing thin pieces of metal from a workpiece with a tool to allow complete joint penetration or to prepare a surface for welding. Gouging can be used to repair weld discontinuities and defects.

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 repair welds.

groove angles

The total included angle of the groove between workpieces being welded together. The size of the groove angle depends on the welding method and requirements.

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.

GTAW

Gas tungsten arc welding. A precise arc welding process that uses a non-consumable tungsten electrode and inert shielding gas. GTAW is also known as tungsten inert gas welding (TIG welding).

HAZ

Heat-affected zone. The portion of the base metal immediately surrounding the weld metal zone. The HAZ does not melt during welding, but its mechanical and physical properties are altered.

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.

heat-affected zone cracks

HAZ cracks. A crack that forms in the heat-affected zone of the base metal. Heat-affected zone cracks are generally longitudinal cracks.

heat-affected zones

HAZs. The portion of the base metal immediately surrounding the weld metal zone. The heat-affected zone does not melt during welding, but its mechanical and physical properties are altered.

hi-lo gage

An instrument that measures alignment on weld joints and internally on pipes. Hi-lo gages can help check for joint misalignment before and after welding.

hot cracks

Fractures in the weld that are often caused by stress in thin materials during solidification. Hot cracking occurs while the weld is still hot and cooling.

hydrogen

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

hydrogen entrapment

The absorption of hydrogen into metal during welding. Hydrogen entrapment can cause metals to lose ductility and crack.

impact strength

The measure of a material's ability to withstand sudden, sharp blows without fracturing or breaking. The impact strength of a weld can be determined by putting the weld through different types of impact testing.

impact testing

A destructive testing method that uses a hammer or other object to strike a weld in order to determine its impact strength and toughness. Impact testing includes methods include the Charpy V-notch test.

incomplete fusion

IF. 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.

inspection

The examination of a part during or after its creation to confirm that it adheres to specifications. Inspection allows welders to identify and correct defects.

intermittent welding

Welding that produces short, evenly spaced welded sections along one or both sides of a joint. Intermittent welding can be used to reduce distortion.

iron

A common silvery-white metal found in nature as ore. Iron is alloyed with carbon to make steel.

joint

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

joint geometry

The dimensions of a welded joint, including the measurements of the weld face, root opening, and included angle. Joint geometry is specified by fabrication drawings and welding codes.

joint misalignment

A weld discontinuity in which two or more workpieces are not properly aligned before they are welded. Joint misalignment, also called joint mismatch, can be prevented by measuring and clamping workpieces.

joint mismatch

A weld discontinuity in which two or more workpieces are not properly aligned before they are welded. Joint mismatch, also called joint misalignment, can be prevented by measuring and clamping workpieces.

liquid penetrant inspection

LPI. A nondestructive testing method that uses a fluorescent liquid or dye to detect surface flaws. Liquid penetrant inspection requires an inspector to apply a penetrant and then a developer to reveal weld discontinuities.

longitudinal crack

A fracture in the surface of a weld that is parallel to the weld axis. Longitudinal cracks include centerline and heat-affected zone cracks.

macro-etch testing

A destructive testing method that involves applying a mildly acidic mixture to a cross-section of a welded joint and examining it for visible flaws. Macro-etch testing is similar to micro-etch testing but is limited to larger scale examination of the internal structure of a weld.

magnetic field

The area surrounding magnets and current-carrying conductors that exerts forces of attraction and repulsion. A magnetic field is used to help identify weld defects in magnetic particle inspection.

magnetic particle inspection

MPI. A nondestructive testing method that uses iron powder to locate discontinuities in a magnetized workpiece. Magnetic particle inspection use magnetic fields to examine a weldment.

mechanical

A property 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.

metallurgical

A measurable characteristic that describes a completed weld and its associated weld and base metal's qualities and capabilities. Metallurgical properties include a variety of physical and mechanical properties, such as strength.

micro-etch testing

A destructive testing method that involves applying a mildly acidic mixture to a cross-section of a welded joint and examining it for microscopic flaws. Micro-etch testing is similar to macro-etch testing but enables smaller scale examination using a microscope.

micrometers

A U-shaped measuring instrument with a threaded spindle that slowly advances toward a small anvil to close around a part. Micrometers provide more precise measurements than calipers.

nick break testing

A destructive testing method in which a small slot is cut into the surface of the weld and the weld is then broken across that slot. Nick break testing allows inspectors to not only measure the strength of a weld but also to examine it for internal defects.

nondestructive testing

NDT. A testing method that does not destroy the workpiece or weld being tested. Nondestructive testing is ideal for large or expensive workpieces.

nonuniform weld

A discontinuity in which the width or height of a weld bead is uneven along its length. Nonuniform welds are unsightly but not necessarily defects.

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.

parallel

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

peening

A tool with a rounded head on one end used in the process of hardening or stretching a surface by striking it. Peening hammers are also known as ball-peen hammers or machinist's hammers.

peening hammer

A hammer with a rounded head on one end used in the process of hardening a surface by striking it. Peening hammers are also known as ball-peen hammers or machinist's hammers.

penetrant

A fluorescent liquid or dye that detects surface flaws. Penetrant tests can be used when magnetic tests cannot be used.

perpendicular

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

physical

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

plane

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

porosity

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

post-heating

The application of heat to a weld immediately after welding, before the weld has cooled. Post-heating helps reduce stress in the weld metal.

pre-bending

A technique of purposely stressing and distorting parts before welding to counteract shrinkage and other distortions that can occur as the weld cools. Pre-bending results in the desired surface after the weld cools and contracts.

preheating

The application of heat to a base metal immediately before welding. Preheating provides several benefits, such as reducing hardness, improving ductility, and decreasing the likelihood of hydrogen cracking.

press

A machine with a stationary base and an upper arm that moves along a vertical axis. Presses are often used in the fillet weld break test.

radiographic testing

RT. A non-destructive testing method that uses electromagnetic waves to detect flaws in a material. Radiographic tests are used to view the insides of solid objects.

receiver

A mechanism designed to receive sound waves. A receiver collects soundwaves to display inspection date during ultrasonic inspection.

reentrant angle

The angle where the weld toes meet the base metal workpieces. Acute reentrant angles are a result of overlap.

root openings

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.

sanding disc

A round piece of woven or non-woven material covered in a coated abrasive. Sanding discs are rotated by motorized devices to remove metal from parts.

shielded metal arc welding

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

shielding

A gas that protects the weld pool and arc from atmospheric contamination. Shielding gases are used in gas metal arc welding, gas tungsten arc welding, and gas-shielded flux-cored arc welding.

shrinkage

The reduction in size that a part experiences as it contracts while cooling after exposure to intense heat. Shrinkage can change the microstructure of metal parts.

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 the cooling metal and is chipped off after the weld has cooled, but it can become trapped inside the finished weld.

slag inclusion

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

SMAW

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

square groove welds

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

stress riser

A groove, notch, or other abnormality that concentrates stress under normal load conditions. Stress risers can lead to cracking and failure.

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 conductivity

The ability of a material to act as a medium for conveying heat. Materials with superior thermal conductivity include aluminum and copper.

throat crack

A central crack in the throat of a weld. Throat cracks are often caused by shrinkage or filler metal with inadequate strength.

T-joints

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.

toe crack

A crack at the toe of a weld, where the weld and base metal meet. Toe cracks are caused by shrinkage.

toughness

The ability of a metal to absorb energy without breaking or fracturing. Toughness is a key property because it determines the ability of a material to withstand sudden stresses.

transverse bend testing

A destructive testing method that bends a welded specimen to determine its strength and durability. Transverse bend testing can test the side, face, or root of a weld.

transverse crack

A fracture in the surface of a weld that is perpendicular to the weld axis. Transverse cracks may be completely within the weld metal or may extend into the HAZ.

transverse tension testing

A destructive testing method that pulls a weld specimen to determine when it breaks . Transverse tension testing is generally required as part of mechanical testing for groove welds.

travel speed

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).

tungsten

A dense, brittle, gray metal that has excellent conductivity and the highest melting point of all pure metals. Tungsten is used to make non-consumable electrodes for GTAW.

tungsten inclusion

A weld defect that occurs when tungsten particles become trapped in the weld metal. Tungsten inclusion only occurs in gas tungsten arc welding.

ultrasonic inspection

UT. A nondestructive testing method that uses high-frequency sound waves to detect internal flaws. In ultrasonic inspection, a discontinuity reflects sound waves and prevents them from reaching the receiver.

ultrasonic peening

A mechanical process that uses high-frequency oscillation or impacts to improve strength and fatigue resistance in welds and other metals. Ultrasonic peening improves the metal’s structure and helps reduce distortion in welds.

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.

unequal leg size

A fillet weld discontinuity in which the weld legs are not equal in length. Unequal leg size is not a defect as long as the legs meet the size requirement of the weld.

visual inspection

The examination of a part for visible surface defects and discontinuities. Visual inspection is one of the most commonly used nondestructive testing methods for finished welds.

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 bead

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

weld cracking

Fracturing that develops in a weld after solidification. Weld cracking is often caused by excessive hardness in a weld, stress, or atmospheric contamination.

weld face

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

weld legs

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

weld pool

The small area of molten metal that forms during welding and that, when cooled, forms the permanent joint. Weld pools are sometimes called weld puddles.

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 toe

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

welding codes

A collection of standards that outline practices for particular welding applications. Welding codes ensure safe welding practices and high-quality welded products.

welding procedure specifications

WPSs. 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.

width-to-depth ratio

A measure of the width of a weld in comparison to its depth. An improper width-to-depth ratio can cause cracking.

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.

work angle

The acute or right angle between the electrode axis and a line horizontally perpendicular to the weld axis. The work angle positions the weld bead in the joint.

worm tracks

A discontinuity in which gas bubbles from the arc become trapped in the weld pool and leave small grooves along the surface. Worm tracks, also known as gas marks, form when slag solidifies and a trapped gas bubble marks the weld bead.

x-ray testing

A nondestructive testing method that uses electromagnetic waves to detect flaws in a material. X-ray testing is used to create a contrasting image of the interior of a weld.

x-rays

An electromagnetic wave with a high frequency and low wavelength. X-rays are used to view the interior of solid objects.