1、Designation: E3052 16Standard Practice forExamination of Carbon Steel Welds Using Eddy CurrentArray1This standard is issued under the fixed designation E3052; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the use of eddy current arraysensors for nondestructive examination of carbon steel welds.It includes the det
3、ection and sizing of surface-breaking cracksin such joints, accommodating for nonmagnetic and noncon-ductive coating up to 5 mm thick (typical) between the sensorand the joint. The practice covers a variety of cracking defects,such as fatigue cracks and other types of planar discontinuities,at vario
4、us locations in the weld (heat-affected zone, toe area,and weld cap, for example). It covers the length and depthsizing of such surface-breaking discontinuities. This practicecan be used for flush-ground and not flush-ground welds. Forspecific ferrous alloys or specific welded parts, the user maynee
5、d a more specific procedure.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of thi
6、s standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E543 Specification for Agencies Performing NondestructiveTestingE1316 Terminology for Nondestructive ExaminationsE2261 P
7、ractice for Examination of Welds Using the Alter-nating Current Field Measurement TechniqueE2884 Guide for Eddy Current Testing of Electrically Con-ducting Materials Using Conformable Sensor ArraysE2905 Practice for Examination of Mill and Kiln Girth GearTeethElectromagnetic Methods2.2 ASNT Document
8、s3SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Certification In Nondestructive TestingANSI/ASNT-CP-189 Standard for Qualification and Certifi-cation of Nondestructive Testing Personnel2.3 Other Standards:ISO 9712 Nondestructive TestingQualification and Certi-fication of Nondestruc
9、tive Testing Personnel4NAS410 Certification and Qualification of NondestructiveTesting Personnel3. Terminology3.1 Definitions: For definitions of terms relating to thispractice, refer to Terminology E1316, Guide E2884 andPractice E2905. The following definitions are specific to theexamination of car
10、bon steel welds using eddy current array:3.1.1 air reference measurement, nthe measured responseof the sensor and instrumentation to a nonmagnetic andelectrically insulating reference material such as air.3.1.1.1 Discussionthe instrument shall process this mea-surement as a reference response for si
11、gnal adjustment. Mea-surements on conductive materials after air reference measure-ment should provide absolute electrical properties and lift-offvalues.3.1.2 encodera spatial sensing device (based onmechanical, optical, or electromagnetic principles, for ex-ample) allowing for accurate monitoring o
12、f a sensors positionduring data collection, used to construct spatially referenceddata presentations.3.1.3 examined part reference measurementthe measuredresponse of the sensor and instrumentation to the magnetic partto be examined.3.1.3.1 Discussionthe instrument shall be capable of mea-suring and
13、recording the response of the sensor on the part tobe examined, and compensate for specific material properties.1This test method is under the jurisdiction of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.07 onElectromagnetic Method.Current edition
14、approved Feb. 1, 2016. Published February 2016. DOI: 10.1520/E3052-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM
15、 website.3Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.4Available from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Verni
16、er,Geneva, Switzerland, http:/www.iso.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.4 known material reference measurementthe mea-sured response of the sensor and instrumentation to a givenmaterial with known, homogeneous pr
17、operties (such as alumi-num 6061-T6, for example).3.1.4.1 Discussionthe instrument shall process this as areference response for signal adjustment and standardization toprovide values that are similar for all of the sense elements.4. Significance and Use4.1 Eddy Current Array for Crack Detection and
18、 Sizing inCarbon Steel WeldsEddy current array allows for a fastexamination of carbon steel welds for surface-breaking crackslocated on the surface closest to the sensor. However, not allECA probe designs allow for accurate depth sizing of suchdiscontinuities over a significant range (several millim
19、eters, forexample). To achieve proper crack depth sizing, the systemshall exhibit certain characteristics, such as: 1) a lift-off signalthat allows monitoring that lift-off over an adequate range ofvalues, 2) suitable phase separation between the lift-off signaland the defect signal, 3) the capabili
20、ty to make use of thelift-off monitoring for crack depth determination, 4) the capa-bility to take into account material properties variations forcrack depth determination along and across the weld and, 5) auniform sensitivity across the sensing elements of the array inorder to provide an effective
21、single-pass examination, as it isexpected when using an array sensor.4.2 Array Sensors and Single Sensing Element SensorsDepending on the weld geometry, it may be possible to useeither a sensor array or a sensor with a single sensing element.The sensor array would provide a better spatial representa
22、tionof the weld and an improved probability of detection. The sizeof the array, as well as the size and number of individualsensing elements within the array depend on the weld geometryand other factors such as target discontinuities. When asingle-sensing element sensor is used, it shall produce sig
23、nalsthat exhibit the characteristics listed in subsection 4.1 and themaximum distance from the scan line to a target discontinuity,potentially detectable at a specified probability of detection, istypically 5 mm.4.3 Conformable SensorsExamining welds that are notground flush typically requires a con
24、formable array sensor,minimally along one axis.Aconformable sensor is key to allowthe individual sensing elements to follow the profile of theweld cap, and to provide a uniform response over the region ofinterest during the examination when the array is orientedtransverse to the weld and scanned alo
25、ng the length of theweld.4.4 Crack Depth RangeThe crack depth sizing range overwhich the array sensor can provide accurate measurementdepends on the sensor geometry, such as individual sensingelement size and configuration. For example, larger sensingelements may provide the ability to size deeper c
26、racks, butoffer limited detection capability for shallow cracks. Appropri-ate array sensor selection and operating frequency is critical toensure adequate performance for a given application. Typicaloperating frequencies range between 10 kHz and 500 kHz.4.5 Coating Thickness RangeThe coating thickne
27、ss rangeover which the array sensor can reliably detect and size cracksdepends on the individual sensing element size and overallprobe geometry, among other parameters. For any coated weldexamination, a verification that the coating thickness is withinthe probe specification range is critical to ens
28、ure adequateresults.4.6 Crack Length RangeThe crack length range overwhich the array sensor performs best depends on the individualsensing element size and on any data processing performed onthe data. The size of the individual sensing element mainlyaffects the minimum crack length detectable, while
29、 dataprocessing (a high pass filter, for example) may have a criticalimpact on the maximum measurable crack length.4.7 Sensitivity UniformityIn order to maximize the prob-ability of detection and allow accurate length and depth sizing,it is critical that the sensitivity across the sense elements of
30、thearray be uniform. The array sensor shall exhibit variations insensitivity no greater than 15%. The sensitivity across the arraydepends on the size and configuration of single sensingelements and shall be considered to determine the overall arrayaccuracy. Overlapping individual sensing elements ma
31、y berequired to achieve the adequate level of sensitivity uniformity(e.g. multiple staggered rows of single sensing elements istypical).4.8 Sizing and AccuracyDepending on the material prop-erties and weld surface condition, there is an optimal measure-ment performance range for the system. The inst
32、rument andsensor array probe, the air reference measurement and knownmaterial reference measurement, along with the operationprocedure typically allow depth sizing within 630 % of its truedepth. Depth sizing accuracy is reduced when the system isoperated outside its optimal range.5. Interferences5.1
33、 Material Properties:5.1.1 Base MetalMagnetic permeability and electricalconductivity of the metal can affect the eddy currentmeasurements, and as such, may have an impact on the cracksizing accuracy. The system must be able to compensate forvariations in the magnetic permeability and electrical con
34、duc-tivity typically found in carbon steels, by using, for example astandardization technique that measures and compensates forbase metal properties.5.1.2 Variations Across the WeldIn welded structures, themagnetic permeability and electrical conductivity may varybetween the weld metal, the heat aff
35、ected zone, and the basemetal. Considering the array sensor is moved along the weldaxis, each individual sensing element is usually exposed torelatively constant material properties. However, from oneindividual sensor to another within the array, significantproperties variation may exist and the ins
36、pection system shallbe able to compensate for those local variations in order toavoid noise and undesired signals in the C-scans.5.2 Weld Geometric FeaturesGeometric features in theweld such as bumps and craters can create non-relevantlocalized signals that will contribute to increasing the noiselev
37、el perceived by each sensor. Typically, such geometricfeatures produce signals that exhibit a phase response that isE3052 162significantly different from a crack-like discontinuity, and canbe easily discriminated. However, the presence of several,large geometric features may reduce the overall sensi
38、tivity ofthe probe.5.3 CoatingNon-conductive and non-magnetic coatingover the weld must be compensated for accurate depth sizing.If a coating thickness exceeds the specified coating thicknessrange of the system, the crack depth sizing accuracy can besignificantly reduced.5.4 Curvature of Examination
39、 SurfaceThe examination ofwelds located along curved surface may affect lift-off andcoating thickness evaluation if the individual sensors are notproperly in contact with the surface (normal to the surface). Ingeneral, the radius of curvature of the inspected part should belarge compared to the sens
40、or length. Bi-dimensional conform-able arrays may have to be used to ensure appropriate sensorcontact with the surface.5.5 Surface RoughnessSurface roughness will create lo-calized lift-off variations that are likely to be different from onesensing element to another within the array. To yield accur
41、atedepth sizing, the individual lift-off variations must be moni-tored and these values used when compensating crack depthmeasurements.5.6 Residual Magnetism in Base MetalLocal residualmagnetism may produce noise signal that can affect datainterpretation. Demagnetization of the surface is recommende
42、dif the examination is performed after a magnetizationtechnique, such as magnetic particle, to ensure that the surfaceis in the non-magnetized state.5.7 TemperatureEddy current measurements are generallyaffected by the temperature of the material under examination.Depth sizing may be affected by ele
43、ctrical conductivity varia-tions that come with temperature variations. Temperaturecorrection is required when the examination has to be doneoutside the normal operation temperature of the sensor.5.8 Pressure of the Probe Against Surface UnderExaminationReadings can be affected by the pressure ex-er
44、ted on the conformable array probe when pressed against thesurface being inspected. The pressure should be sufficient tomaintain each individual sensor in contact with the part beingexamined. Array sensors made of a rigid body matching theprofile of the surface under examination only require minimal
45、pressure to maintain good contact with the surface.6. Basis of Application6.1 The following item is subject to contractual agreementbetween the parties using or referencing this standard practice.6.2 Personnel Qualification:6.2.1 If specified in the contractual agreement, personnelperforming examina
46、tions to this practice shall be qualified inaccordance with a nationally or internationally recognizedNDT personnel qualification practice or standard such asANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, ISO 9712, or asimilar document and certified by the employer or certifyingagency, as applicable. The pra
47、ctice or standard used and itsapplicable revision shall be identified in the contractual agree-ment between the using parties.6.3 Qualification of Nondestructive Testing AgenciesIfspecified in the contractual agreement, NDT agencies shall bequalified and evaluated as specified in Practice E543. Thea
48、pplicable edition of Practice E543 shall be specified in thecontractual agreement.6.4 Procedures and TechniquesThe procedures and tech-niques to be utilized shall be as specified in the contractualagreement.6.5 Surface PreparationThe pre-examination surfacepreparation criteria shall be in accordance
49、 with the require-ments specified in the contractual agreement.6.6 Timing of ExaminationThe timing of examinationshall be in accordance with the applicable contractual agree-ment.6.7 Extent of ExaminationThe extent of examination shallbe in accordance with the applicable contractual agreement.6.8 Reporting Criteria/Acceptance CriteriaReporting cri-teria for the examination results shall be in accordance withSection 9 unless otherwise specified. Since acceptance criteriaare not specified in this standard, they shall be specified in thecontractual agr
