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A-Scan Display, Abrasion test , Abrasive wear, Absorbed Does, Absorption, Absorption Coefficient, Absorption Coefficient, Linear, Acceptance Standard , Accuracy class, Acoustic Emission Testing (AE), Acoustic Impedance (Z), Acoustic Properties, Adhesive wear, Adjustment of a measuring system, Alligator skin, Alligatoring, Alpha Radiation, Alternating Current (AC), Ambient, Amperage, Ampere , Angle Beam Testing, Angle Beam Transducers, Angle of Incidence, Angle of Reflection, Angle of Refraction, Angular Frequency , Annealing twin, Anode, Anode, Arrest lines (marks), Asperity, Atomic Number, Attenuation, Attenuation Coefficient , Austenite, Authorized qualifying body, Axial, Axial strain, B-scan , Back Reflection, Back Scatter , Background indication, Backing, Bainite , Banded structure, Base gas, Base quantity , Basic examination, Beach marks, Beam Alignment Measurements, Beam Exit Point, Beam Profiles, Beam Spread , Black-light , Blank indication, Bottom Echo , Breakage causes of components, Breaking stress, Brinell hardness HB, Brinell hardness test, Brinelling, Brittle, Brittle crack propagation, Brittle erosion behavior, Brittle fracture, Brittleness, Buckle, Buckling, Bulk modulus, Bulk modulus of elasticity, K, C-scan , Calibration, Calibration , Calibration curve, Calibration diagram, Calibration Reflector , Candidate, Capping run, Carbon flotation, Casting shrinkage, Certificate, Certification, Certification body, Cleavage, Cobalt 60 , Coefficient of Thermal Expansion, Coefficients, Coherent derived unit, Coil , Collimation, Color-Contrast Penetrant , Combined standard measurement uncertainty, Comparative Test Block, Composite , Compressional Wave, Concentration, Conductivity, Conductors, Contact Transducers, Contrast (radiographic) , Conversion factor between units, Correction, Corrosion, Corrosion, Coverage factor, Coverage interval, Coverage probability, Cracks, Creep, Critical Angle, Curie , Current (I), Damping, Dead band, Decarburization , Decibel, Decontamination, Defect, Definition, Deflection, Deformation, Deformation bands, Delamination , Demagnetization, Dendrite , Dendrite, Denickelification, Densitometer , Density, Depletion, Deposit attack, Deposit attack., Depth Compensation, Depth of Fusion , Depth of Penetration (Standard), Derived quantity, Detection limit, Detector, Detector, Developer (Penetrant), Developing Time , Dezincification, Diamagnetic Materials , Diamond pyramid hardness test, Differential Probe , Diffraction , Dimpled rupture fracture, Direct Current (DC), Discontinuity , Discrimination threshold, Dispersion, Displaying measuring instrument, Dissimilar material joint, Distance Amplitude Correction (DAC), Distance-Amplitude Blocks , Distance-Amplitude Response Curve, Distorted Field, Distortion, Divergence , Dose , Dosimeter , Ductile crack propagation, Ductile erosion behaviour, Ductile fracture, Ductility, Dynamic, A-B

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Home > Company Profile
Company Profile - Glossary of terms


A-B E-F G-L M-Q T-Z Other
Non-destructive testing - GLOSSARY
A-Scan Display
A data presentation method in which signal amplitude is plotted along the y-axis versus time on the x-axis. The horizontal distance between any two signals represents the material distance between the two conditions causing the signals. In a linear system, the vertical excursion is proportional to the amplitude of the signal.
Materials Testing Centre - GLOSSARY
Abrasion test
The process of grinding or wearing away through the use of abrasives; a roughening or scratching of a surface due to abrasive wear.
Materials Testing Centre - GLOSSARY
Abrasive wear
The removal of material from a surface when hard particles slide or roll across the surface under pressure. The particles may be loose or may be part of another surface in contact with the surface being abraded. Compare with adhesive wear.
Non-destructive testing - GLOSSARY
Absorbed Does
The amount of energy, imparted to matter by an ionizing particle per unit mass of irradiated material at the place of interest. It is expressed in rads.
Non-destructive testing - GLOSSARY
Absorption
The taking up of energy from the medium through which it passes.
Non-destructive testing - GLOSSARY
Absorption Coefficient
The ratio of energy absorbed by a medium or material to the energy incident on the surface. If a flux through a material decreases with distance x in proportion to e-ax, then a is called the absorption coefficient. Also known as the absorption factor; absorption ratio; coefficient of absorption.
Non-destructive testing - GLOSSARY
Absorption Coefficient, Linear
The fractional decrease in transmitted intensity per unit of absorber thickness. It is usually designated by the symbol µ and expressed in units of (cm-1.2).
Non-destructive testing - GLOSSARY
Acceptance Standard
A controlled specimen containing natural or artificial discontinuities that are well defined and similar to the maximum acceptable discontinuity, in size and extent, in the product.
Calibration Centre - GLOSSARY
Accuracy class
Accuracy class: class of measuring instruments or measuring systems that meet stated metrological requirements that are intended to keep measurement errors or instrumental uncertainties within specified limits under specified operating conditions.
Non-destructive testing - GLOSSARY
Acoustic Emission Testing (AE)
A nondestructive testing method that "listens" for transient elastic-waves generated due to a rapid release of strain energy caused by a structural alteration in a solid material. 
Non-destructive testing - GLOSSARY
Acoustic Impedance (Z)
The resistance of a material to the passage of sound waves. The value of this material property is the product of the material density and sound velocity. The acoustic impedance of a material determines how much sound will be transmitted and reflected when the wave encounters a boundary with another material. The larger the difference in acoustic impedance between two materials, the larger the amount of reflected energy will be.
Non-destructive testing - GLOSSARY
Acoustic Properties
 Intrinsic characteristics of any particular material that describe how sound travels through it. Such characteristics include the density, acoustic impedance, and sound velocity.
Materials Testing Centre - GLOSSARY
Adhesive wear
The removal or displacement of material from a surface by the welding together and subsequent shearing of minute areas of two surfaces that slide across each other under pressure. Compare with abrasive wear.
Calibration Centre - GLOSSARY
Adjustment of a measuring system
Adjustment of a measuring system: set of operations carried out on a measuring system so that it provides prescribed indications corresponding to given values of a quantity to be measured.
Materials Testing Centre - GLOSSARY
Alligator skin
See orange peel.
Materials Testing Centre - GLOSSARY
Alligatoring
The longitudinal splitting of flat slabs in a piane parallel to the rolled surface. Also called fishmouthing.
Non-destructive testing - GLOSSARY
Alpha Radiation
A stream of fast-moving helium nuclei. This is a strongly ionizing radiation with very weak penetration (e.g. cannot penetrate a piece of paper).
Non-destructive testing - GLOSSARY
Alternating Current (AC)
 Electric current that reverses direction periodically (usually many times per second).
Materials Testing Centre - GLOSSARY
Ambient
Surrounding; usually used in relation to temperature, as "ambient temperature" surrounding a certain part or assembly.
Non-destructive testing - GLOSSARY
Amperage
A term used to describe the strength of electric current. The number of electrons moving past a fixed point in a conductor in one second. Measured in amperes. The term amps is often used for short.
Non-destructive testing - GLOSSARY
Ampere
A standard unit of measure for electric current or the flow of electrons. The amount of current sent by one volt through a resistance of one ohm.
Non-destructive testing - GLOSSARY
Angle Beam Testing
An ultrasound testing technique that uses an incidence wave angle other than 90 degrees to the test surface. The refracted angle of the sound energy is calculated using Snell's law.
Non-destructive testing - GLOSSARY
Angle Beam Transducers
A device used generated sound energy, send the energy into a material at angle other than 90 degrees to the surface, and receive reflected energy and convert it to electrical pulses.
Non-destructive testing - GLOSSARY
Angle of Incidence
The angle between the direction of propagation of an electromagnetic or acoustic wave (or ray) incident on a body and the local normal to that body.
Non-destructive testing - GLOSSARY
Angle of Reflection
The angle between the direction of propagation of an electromagnetic or acoustic wave (or ray) reflected by a body and the local normal to that body.
Non-destructive testing - GLOSSARY
Angle of Refraction
The angle between the direction of propagation of an electromagnetic or acoustic wave (or ray) refracted by an optically homogeneous body and the local normal to that body.
Non-destructive testing - GLOSSARY
Angular Frequency
For any oscillation, the number of vibrations per unit time, multiplied by 2π. Also known as angular velocity and radian frequency.
Materials Testing Centre - GLOSSARY
Annealing twin
A twin formed in a crystal during recrystallization.
Materials Testing Centre - GLOSSARY
Anode
The electrode of an electrolytic cell at which oxidation occurs. Contrast with cathode.
Non-destructive testing - GLOSSARY
Anode
(1) The positive terminal or the collector of electrons in an electrical system (i.e. the positive terminal of a battery) (2) The electrode at which oxidation or corrosion occurs. It is the opposite of cathode.
Materials Testing Centre - GLOSSARY
Arrest lines (marks)
See beach marks.
Materials Testing Centre - GLOSSARY
Asperity
In tribology, a protuberance in the small-scale topographical irregularities of a solid surface.
Non-destructive testing - GLOSSARY
Atomic Number
A number representing the positive charge or number of protons in the nucleus of an atom.
Non-destructive testing - GLOSSARY
Attenuation
The reduction in the level of a quantity, such as the intensity of a wave or radiation.
Non-destructive testing - GLOSSARY
Attenuation Coefficient
A factor which is determined by the degree of reduction in sound wave energy per unit distance traveled. It is composed of two parts, one (absorption) proportional to frequency, the other (scattering) dependent on the ratio of grain size or particle size to wavelength.
Non-destructive testing - GLOSSARY
Austenite
A nonmagnetic solid solution of ferric carbide or carbon in iron. An elevated-temperture parent phase in ferrous metals from which all other low-temperature structures are derived. The normal structures are derived. The normal condition of certain types of stainless steels.
Certification - GLOSSARY
Authorized qualifying body
Body, independent of the employer, authorized by the certification body to prepare and administer qualification examinations.
Materials Testing Centre - GLOSSARY
Axial
Longitudinal, or parallel to the axis or centerline of a part. Usually refers to axial compression or axial tension.
Materials Testing Centre - GLOSSARY
Axial strain
Increase (or decrease) in length resulting from a stress acting parallel to the longitudinal axis of a test specimen.
Non-destructive testing - GLOSSARY
B-scan
A data presentation method applied to pulse echo techniques. It produces a two-dimensional view of a cross-sectional plane through the test object. The horizontal sweep is proportional to the distance along the test object and the vertical sweep is proportional to depth, showing the front and back surfaces and discontinuities between.
Non-destructive testing - GLOSSARY
Back Reflection
The signal received from the far boundary or back surface of a test object.
Non-destructive testing - GLOSSARY
Back Scatter
 Scattered signals that are directed back to the transmitter/receiver.
Calibration Centre - GLOSSARY
Background indication
Background indication: indication obtained from a phenomenon, body, or substance similar to the one under investigation, but for which a quantity of interest is supposed not to be present, or is not contributing to the indication.
Welding Technology - GLOSSARY
Backing
Material placed at the reverse side of a joint preparation for the purpose of supporting molten weld metal.
Non-destructive testing - GLOSSARY
Bainite
An intermediate transformation product from austenite in the heat treatment of steel. Bainite can somewhat resemble pearlite or martensite, depending on the transformation temperature.
Materials Testing Centre - GLOSSARY
Banded structure
A segregrated structure consisting of alternating, nearly parallel bands of different composition, typically aligned in the direction of primary hot working.
Welding Technology - GLOSSARY
Base gas
Major or only component of a pure or mixed gas.
Calibration Centre - GLOSSARY
Base quantity
Quantity in a conventionally chosen subset of a given system of quantities, where no subset quantity can be expressed in terms of the others
Certification - GLOSSARY
Basic examination
Esame di livello 3 che dimostra la conoscenza del candidato sulla tecnologia e sulla scienza dei materiali, relative al settore di attività del candidato, del sistema di qualificazione e di certificazione e dei principi di base dei metodi PND come
richiesto per il livello 2.
Materials Testing Centre - GLOSSARY
Beach marks
Macroscopic (visible) progression marks on a fracture surface that indicate
successive position of the advancing crack front. The classic appearance is of irregular elliptical or semielliptical rings, radiating outward from one or more origins. Beach marks (also known as clamshell marks, tide marks, or arrest marks) are typically found on service fractures where the part is loaded randomly, intermittently, or with periodic variations in mean stress or alternating stress. Not to be confused with striations, which are microscopic and form differently.
Non-destructive testing - GLOSSARY
Beam Alignment Measurements
Measurements that provide data on the degree of alignment between the sound beam axis and the transducer housing. This information is particularly useful in applications that require a high degree of certainty regarding beam positioning with respect to a mechanical reference surface.
Non-destructive testing - GLOSSARY
Beam Exit Point
See probe index.
Non-destructive testing - GLOSSARY
Beam Profiles
A measurement of the intensity of the beam across its width (or profile). It provides valuable information about transducer sound field characteristics.
Non-destructive testing - GLOSSARY
Beam Spread
The divergence of the sound beam as it travels through a medium. Specifically, the solid angle that contains the main lobe of the beam in the far field.
Non-destructive testing - GLOSSARY
Black-light
See ultraviolet light.
Calibration Centre - GLOSSARY
Blank indication
Blank indication: indication obtained from a phenomenon, body, or substance similar to the one under investigation, but for which a quantity of interest is supposed not to be present, or is not contributing to the indication.
Non-destructive testing - GLOSSARY
Bottom Echo
See back reflection.
Breakage causes of components
On the TEC Eurolab website you can find information about root causes of breakage of components
Materials Testing Centre - GLOSSARY
Breaking stress
See rupture stress.
Materials Testing Centre - GLOSSARY
Brinell hardness HB
A number related to the applied load and to the surface area of the permanent impression made by a ball indenter.
Materials Testing Centre - GLOSSARY
Brinell hardness test
A test for determining the hardness of a material by forcing a hard steel or carbide bali of specified diameter into it under a specified load. The result is expressed as the Brinell hardness number.
Materials Testing Centre - GLOSSARY
Brinelling
Damage to a solid bearing surface characterized by one or more plastically formed indentations brought about by overload. This term is often applied in the case of rolling-element bearings. See also false brinelling.
Materials Testing Centre - GLOSSARY
Brittle
Permitting little or no plastic (permanent) deformation prior to fracture.
Materials Testing Centre - GLOSSARY
Brittle crack propagation
A very sudden propagation of a crack with the absorption of no energy except that stored elastically in the body. Microscopic examination may reveal some deformation not noticeable to the unaided eye. Contrast with ductile crack propagation.
Materials Testing Centre - GLOSSARY
Brittle erosion behavior
Erosion behavior having characteristic properties (e. g., little or no plastic flow, the formation of cracks) that can be associated with brittle fracture of the exposed surface. The maximum volume removal occurs at an angle near 90°, in contrast to approximately 25° for ductile erosion behavior.
Materials Testing Centre - GLOSSARY
Brittle fracture
Separation of a solid accompanied by little or no macroscopic plastic deformation. Typically, brittle fracture occurs by rapid crack propagation with less expenditure of energy than for ductile fracture.
Materials Testing Centre - GLOSSARY
Brittleness
The tendency of a material to fracture without first undergoing significant plastic deformation. Contrast with ductility.
Materials Testing Centre - GLOSSARY
Buckle
(1)An indented valley in the surface of a sand casting due to expansion of the molding Band. (2) A local waviness in metal bar or sheet, usually transverse to the direction of rolling.
Materials Testing Centre - GLOSSARY
Buckling
A compression phenomenon that occurs when, after some critical level of load, a bulge, bend, bow, kink, or other wavy condition is produced in a beam, column, plate, bar, or sheet product form.
Materials Testing Centre - GLOSSARY
Bulk modulus
See bulk modulus of elasticity.
Materials Testing Centre - GLOSSARY
Bulk modulus of elasticity, K
The measure of resistance to change in volume; the ratio of hydrostatic stress to the corresponding unit change in volume.
Non-destructive testing - GLOSSARY
C-scan
A data presentation method applied to pulse echo and transmission techniques. It yields a two-dimensional plan view of the object. No indication of depth is given unless special gating procedures are used.
Calibration Centre - GLOSSARY
Calibration
Calibration: operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications.
Non-destructive testing - GLOSSARY
Calibration
The process whereby the magnitude of the output of a measuring instrument is related to the magnitude of the input force driving the instrument (i.e. Adjusting a weight scale to zero when there is nothing on it).
Calibration Centre - GLOSSARY
Calibration curve
Calibration curve: expression of the relation between indication and corresponding measured quantity value.
Calibration Centre - GLOSSARY
Calibration diagram
Calibration diagram: graphical expression of the relation between indication and corresponding measurement result.
Non-destructive testing - GLOSSARY
Calibration Reflector
A reflector with a known dimensioned surface established to provide an accurately reproducible reference measurement.
Certification - GLOSSARY
Candidate
Individual seeking qualification and certification who gains experience under the supervision of suitably qualified personnel.
Welding Technology - GLOSSARY
Capping run
In multi layer welding, the run(s) visible on the weld face(s) after completion of welding.
Materials Testing Centre - GLOSSARY
Carbon flotation
Segregation in which free graphite has separated from the molten iron. This defect tends to occur at the upper surfaces of the cope of the castings.
Materials Testing Centre - GLOSSARY
Casting shrinkage
See liquid shrinkage, shrinkage cavity, solidification shrinkage, and solid shrinkage.
Catastrophic wear. Rapidly occurring or accelerating surface damage, deterioration, or change of shape caused by wear to such a degree that the service life of a part is appreciably shortened or its function is destroyed.
Certification - GLOSSARY
Certificate
Document issued by the certification body under the provisions of this European Standard, indicating that the named person has demonstrated the competence(s) defined on the certificate.
Certification - GLOSSARY
Certification
Procedure used by the certification body to confirm that the qualification requirements for a method, level and sector have been fulfilled, leading to the issuing of a certificate.
Certification - GLOSSARY
Certification body
Body that administers procedures for certification according to the requirements of this European Standard and which fulfils the requirements of EN ISO/IEC 17024.
Materials Testing Centre - GLOSSARY
Cleavage
(1) Fracture of a crystal by crack propagation across a crystallographic piane of low index. (2) The tendency to cleave or split along definite crystallographic planes.
Non-destructive testing - GLOSSARY
Cobalt 60
A radioisotope of the element cobalt.
Non-destructive testing - GLOSSARY
Coefficient of Thermal Expansion
The linear expansion or contraction per unit length per degree temperatures between specified lower and upper temperatures.
Non-destructive testing - GLOSSARY
Coefficients
A constant chemical or physical property constant for a system with specific conditions (i.e. Coefficient of Friction).
Calibration Centre - GLOSSARY
Coherent derived unit
Coherent derived unit: derived unit that, for a given system of quantities and for a chosen set of base units, is a product of powers of base units with no other proportionality factor than one.
Non-destructive testing - GLOSSARY
Coil
More than one loop of a conductor wound in a spiral. Also called a solenoid.
Non-destructive testing - GLOSSARY
Collimation
The process by which a beam of energy or particles is aligned to form a parallel beam.
Non-destructive testing - GLOSSARY
Color-Contrast Penetrant
A penetrant incorporating a color dye or sufficient intensity to give good color contrast in indications against the background of the surface being tested, when viewed under white light.
Calibration Centre - GLOSSARY
Combined standard measurement uncertainty
Combined standard measurement uncertainty: standard measurement uncertainty that is obtained using the individual standard measurement uncertainties associated with the input quantities in a measurement model.
Non-destructive testing - GLOSSARY
Comparative Test Block
A metal block specially cracked and having two separate, but adjacent areas for the application of different penetrants so that a direct comparison can be obtain.
Non-destructive testing - GLOSSARY
Composite
A product that is produced by combining several different material products to arrive at desired set of properties. Fiber glass, carbon graphite epoxy, and carbon fiber are examples of composite material.
Non-destructive testing - GLOSSARY
Compressional Wave
A wave in which the particle motion in the material is parallel to the wave propagation direction. Also called a longitudinal wave.
Materials Testing Centre - GLOSSARY
Concentration
Non-destructive testing - GLOSSARY
Conductivity
A measure of the ability of a material to conduct electrical current.
Non-destructive testing - GLOSSARY
Conductors
Materials that have free electrons and allow electrical current to flow easily.
Non-destructive testing - GLOSSARY
Contact Transducers
An ultrasonic transducer that is designed to be used in direct contact with the surface of the test article.
Non-destructive testing - GLOSSARY
Contrast (radiographic)
The measure of difference in the film or detector density (darkness) from one area to another, resulting from various X-ray intensities interacting with the detector.
Calibration Centre - GLOSSARY
Conversion factor between units
Conversion factor between units: ratio of two measurement units for quantities of the same kind.
Calibration Centre - GLOSSARY
Correction
Correction: compensation for an estimated systematic effect.
Non-destructive testing - GLOSSARY
Corrosion
Deterioration of a metal by chemical or electrochemical reaction with its environment.
Materials Testing Centre - GLOSSARY
Corrosion
Definition of corrosion: the chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties
Calibration Centre - GLOSSARY
Coverage factor
Coverage factor: number larger than one by which a combined standard measurement uncertainty is multiplied to obtain an expanded measurement uncertainty A coverage factor is usually symbolized k.
Calibration Centre - GLOSSARY
Coverage interval
Coverage interval: interval containing the set of true quantity values of a measurand with a stated probability, based on the information available.
Calibration Centre - GLOSSARY
Coverage probability
Coverage probability: probability that the set of true quantity values of a measurand is contained within a specified coverage interval.
Cracks
Defects or cracks of the component, a corrosive presence or a covering detach are damages which can appear during the component utilization in all those fields where metallic alloys employment is requested.
Creep
Definition of creep: time-dependent strain occurring under stress. The creep strain occurring at a diminishing rate is called primary or transient creep; that occurring at a minimum and almost constant rate, secondary or steadyrate creep; that occurring at an accelerating rate, tertiary creep.
Non-destructive testing - GLOSSARY
Critical Angle
The first angel of the incident sound wave that generates a refracted wave that travels along the incident surface. The first angle that results in a surface following longitudinal wave is known as the 1st critical angle and the first angle that results in surface following shear wave is known as the 2nd critical angle.
Non-destructive testing - GLOSSARY
Curie
The basic unit of measure for describing the activity (radioactivity) of a quantity of radioactive material. The amount of radioactive material giving off 37 billion disintegrations per second. In the United States, the picocurie (1 pCi = 0.037 d.p.s.) is the unit used for many measurements of radioactive contamination.
Non-destructive testing - GLOSSARY
Current (I)
The flow of electrons. Measured in amperes. 
Non-destructive testing - GLOSSARY
Damping
Limiting the duration or decreasing the amplitude of vibrations.
Calibration Centre - GLOSSARY
Dead band
Dead band: maximum interval through which a value of a quantity being measured can be changed in both directions without producing a detectable change in the corresponding indication.
Materials Testing Centre - GLOSSARY
Decarburization
 Loss of carbon from the surface layer of a carbon-containing alloy due to reaction with one or more chemical substances in a medium that contacts the surface.
Non-destructive testing - GLOSSARY
Decibel
A logarithmic unit for expressing power relationships. n = 10 log10(I1/I2) where n is the difference of decibels of intensities 1 & 2. 
Non-destructive testing - GLOSSARY
Decontamination
The removal of radioactive contaminants from surfaces.
Non-destructive testing - GLOSSARY
Defect
A discontinuity or other imperfection causing a reduction in the quality of a material or component.
Non-destructive testing - GLOSSARY
Definition
The sharpness of features on a radiograph that correspond to boundaries from thickness or material density changes in the radiographed component.
Non-destructive testing - GLOSSARY
Deflection
Deformation within the elastic range caused by a load or force that does not exceed the elastic limit of the material. Temporary deformation such as that of a spring.
Materials Testing Centre - GLOSSARY
Deformation
A change in the form of a body due to stress, thermal change, change in moisture, or other causes. Measured in units of length.
Materials Testing Centre - GLOSSARY
Deformation bands
 Bands produced within individual grains during cold working which differ variably in orientation from the matrix.
Non-destructive testing - GLOSSARY
Delamination
A laminar discontinuity such as an area of unbonded materials.
Non-destructive testing - GLOSSARY
Demagnetization
The process of removing existing magnetism from a part.
Non-destructive testing - GLOSSARY
Dendrite
A crystal that has a tree-like branching pattern, being most evident in cast metals slowly cooled through the solidification range.
Materials Testing Centre - GLOSSARY
Dendrite
A crystal with a treelike branching pattern. Dendrites are most evident in cast metals slowly cooled through the solidification range.
Materials Testing Centre - GLOSSARY
Denickelification
Corrosion in which nickel is selectively leached from nickel-containing alloys. Most commonly observed in coppernickel alloys after extended service in fresh water. See also selective leaching.
Non-destructive testing - GLOSSARY
Densitometer
An instrument used to measure the degree of darkening of developed radiographic film.
Non-destructive testing - GLOSSARY
Density
The mass of a substance per unit volume.
Materials Testing Centre - GLOSSARY
Depletion
Selective removal of one component of an alloy, usually from the surface or preferentially from grain-boundary regions. See also selective leaching.
Materials Testing Centre - GLOSSARY
Deposit attack
See poultice corrosion. deposit corrosion. See poultice corrosion.
Dezincification. Corrosion in which zinc is selectively leached from zinc-containing alloys. Most commonly found in copper-zinc alloys containing less than 85% Cu after extended service in water containing dissolved oxygen. See also selective leaching.
Materials Testing Centre - GLOSSARY
Deposit attack.
See poultice corrosion. deposit corrosion. See poultice corrosion.
Dezincification. Corrosion in which zinc is selectively leached from zinc-containing alloys. Most commonly found in copper-zinc alloys containing less than 85% Cu after extended service in water containing dissolved oxygen. See also selective leaching.
Non-destructive testing - GLOSSARY
Depth Compensation
See distance amplitude correction.
Non-destructive testing - GLOSSARY
Depth of Fusion
The depth to which the base metal melted and fused during welding.
Non-destructive testing - GLOSSARY
Depth of Penetration (Standard)
The depth to which the eddy current density has decreased to 1/e or 36.8% of the surface density. Also known as skin depth.
Calibration Centre - GLOSSARY
Derived quantity
Derived quantity: quantity, in a system of quantities, defined in terms of the base quantities of that system.
Calibration Centre - GLOSSARY
Detection limit
Detection limit: measured quantity value, obtained by a given measurement procedure, for which the probability of falsely claiming the absence of a component in a material is ß, given a probability ß of falsely claiming its presence.
Non-destructive testing - GLOSSARY
Detector
A device that determines the presence of or measures the amount of energy, such as radiation.
Calibration Centre - GLOSSARY
Detector
Detector: device or substance that indicates the presence of a phenomenon, body, or substance when a threshold value of an associated quantity is exceeded.
Non-destructive testing - GLOSSARY
Developer (Penetrant)
A finely divided powder applied over the surface of a part to help bring out penetrant indications.
Non-destructive testing - GLOSSARY
Developing Time
The time between the application of the developer and the examination of the part for indications.
Materials Testing Centre - GLOSSARY
Dezincification
Corrosion in which zinc is selectively leached from zinc-containing alloys. Most commonly found in copper-zinc alloys containing less than 85% Cu after extended service in water containing dissolved oxygen. See also selective leaching.
Non-destructive testing - GLOSSARY
Diamagnetic Materials
Materials that have all paired electrons in the atoms and thus have no net magnetic moment. The magnetic permeability of diamagnetic materials is usually very close to 1.
Materials Testing Centre - GLOSSARY
Diamond pyramid hardness test
See Vickers hardness test.
Non-destructive testing - GLOSSARY
Differential Probe
A probe having two sensing coils located side-by-side allowing it to convert a floating signals to a low voltage ground referenced signal to be displayed on a ground referenced oscilloscope.
Non-destructive testing - GLOSSARY
Diffraction
Any redistribution in space of the intensity of waves that results from the presence of an object causing variations of either the amplitude or phase of the waves.
Materials Testing Centre - GLOSSARY
Dimpled rupture fracture
A fractographic term describing ductile fracture that occurs through the formation and coalescence of microvoids (dimples) along the fracture path. The fracture surface of such a ductile fracture appears dimpled when observed at high magnification and usually is most clearly resolved when viewed in a scanning electron microscope.
Non-destructive testing - GLOSSARY
Direct Current (DC)
 Electrical current that flows in only one direction in a circuit. 
Non-destructive testing - GLOSSARY
Discontinuity
A break in the continuity of a medium or material.
Calibration Centre - GLOSSARY
Discrimination threshold
Discrimination threshold: largest change in a value of a quantity being measured that causes no detectable change in the corresponding indication.
Non-destructive testing - GLOSSARY
Dispersion
The variation of phase velocity with frequency. In general, any process separating radiation into components having different frequencies, energies, velocities, or other characteristics.
Calibration Centre - GLOSSARY
Displaying measuring instrument
Displaying measuring instrument: indicating measuring instrument where the output signal is presented in visual form.
Welding Technology - GLOSSARY
Dissimilar material joint
Welded joint in which the parent materials have significant differences in mechanical properties and/or chemical composition.
Non-destructive testing - GLOSSARY
Distance Amplitude Correction (DAC)
Compensation of gain as a function of time for difference in amplitude of reflections from equal reflectors at different sound travel distances. Refers also to compensation by electronic means such as swept gain, time corrected gain, time variable gain and sensitivity time control.
Non-destructive testing - GLOSSARY
Distance-Amplitude Blocks
A set of ultrasonic reference specimens in which each specimen has a different metal path length to a equal-sized reflector. The specimens are used to develop distance amplitude response curves.
Non-destructive testing - GLOSSARY
Distance-Amplitude Response Curve
A curve showing the relationship between signal amplitude and equal-sized reflecting surfaces at various distances from the transducer. Standard blocks are used to obtain such curve.
Non-destructive testing - GLOSSARY
Distorted Field
A magnetic field that does not follow a straight path or have a uniform distribution due to the irregular in shape of the magnetized test object. The direction of a magnetic field in a symmetrical object will be substantially uniform if produced by a uniformly applied magnetizing force, as in the case of a bar magnetized in a solenoid.
Materials Testing Centre - GLOSSARY
Distortion
 Any deviation from an original size, shape, or contour that occurs because of the application of stress or the release of residual stress.
Non-destructive testing - GLOSSARY
Divergence
An improper term used to describe the spreading of ultrasonic waves beyond the near field. It is a function of transducer diameter and wavelength in the medium.
Non-destructive testing - GLOSSARY
Dose
The amount of ionizing radiation energy absorbed per unit mass of irradiated material at a specific location, such as a part of the human body. Measured in reps, rems per hour.
Non-destructive testing - GLOSSARY
Dosimeter
A device that measures radiation dose, such as a film badge or ionization chamber.
Materials Testing Centre - GLOSSARY
Ductile crack propagation
Slow crack propagation that is accompanied by noticeable plastic deformation and requires energy to be supplied from outside the body. Contrast with brittle crack propagation.
Materials Testing Centre - GLOSSARY
Ductile erosion behaviour
Erosion behaviour having characteristic properties (i.e., considerable plastic deformation) that can be associated with ductile fracture of the exposed solid surface. A characteristic ripple pattern forms on the exposed surface at low values of angle of attack. Contrast with brittle erosion behaviour.
Materials Testing Centre - GLOSSARY
Ductile fracture
racture characterized by tearing of metal accompanied by appreciable gross plastic deformation and expenditure of considerable energy. Contrast with brittle fracture.
Materials Testing Centre - GLOSSARY
Ductility
The ability of a material to deform plastically before fracturing. Measured by elongation or reduction of area in a tension test, by height of cupping in a cupping test, or by the radius or angle of bend in a bend test. Contrast with brittleness; see also plastic deformation.
Materials Testing Centre - GLOSSARY
Dynamic
Moving, or having high velocity. Frequently used with high strain rate (>0.1 s-') testing of metal specimens. Contrast with static.

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