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	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 Technology - 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 Technology - 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 Technology - 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 Technology - GLOSSARY Alligator skin See orange peel.


	Materials Technology - 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 Technology - 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 Technology - GLOSSARY Annealing twin A twin formed in a crystal during recrystallization.


	Materials Technology - 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 Technology - GLOSSARY Arrest lines (marks) See beach marks.


	Materials Technology - 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 of personnel - GLOSSARY Authorized qualifying body Body, independent of the employer, authorized by the certification body to prepare and administer qualification examinations.


	Materials Technology - GLOSSARY Axial Longitudinal, or parallel to the axis or centerline of a part. Usually refers to axial compression or axial tension.


	Materials Technology - 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 Technology - 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 of personnel - 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 Technology - 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.


	Materials Technology - GLOSSARY Breaking stress See rupture stress.


	Materials Technology - 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 Technology - 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 Technology - 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 Technology - GLOSSARY Brittle Permitting little or no plastic (permanent) deformation prior to fracture.


	Materials Technology - 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 Technology - 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 Technology - 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 Technology - GLOSSARY Brittleness The tendency of a material to fracture without first undergoing significant plastic deformation. Contrast with ductility.


	Materials Technology - 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 Technology - 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 Technology - GLOSSARY Bulk modulus See bulk modulus of elasticity.


	Materials Technology - 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.


	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 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.


	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 of personnel - 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 Technology - 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 Technology - 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 of personnel - 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 of personnel - 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 of personnel - 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 Technology - 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 Technology - 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.


	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.


	Non-destructive testing - GLOSSARY Crack A long narrow discontinuity.


	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 Technology - 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 Technology - 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 Technology - 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 Technology - GLOSSARY Dendrite A crystal with a treelike branching pattern. Dendrites are most evident in cast metals slowly cooled through the solidification range.


	Materials Technology - 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 Technology - 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 Technology - 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 Technology - 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.


	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 Detector A device that determines the presence of or measures the amount of energy, such as radiation.


	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 Technology - 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 Technology - 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 Technology - 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 Technology - 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 Technology - 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 Technology - 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 Technology - 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 Technology - 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 Technology - 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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