MagneticParticleTesting Standard Guidefor
This standard is isued under the fsed designation E709; the mmber immedhately folwing the designation indiates the yar of supetstipt psiln () indicates an ditrial chnge sine the lst reisin or reappel.
original adoption oc in the case of revisin the year of last revision. A mumber in parentheses indicates the year of last reapproval. A
part versus those which need not be removed before part and orientation of indications that are unacceptable in a specificacceptance. Conditions where rework or repair is not permittedshould be specified.
magnetic particle testing a nondestructive method for detect- 1.1 This guide² covers techniques for both dry and wetferromagnetic materials. Magnetic particle testing may be ing cracks and other discontinuities at or near the surface inapplied to raw material semifinished material (billets blooms of heat treatment or lack thereof. It is useful for preventive castings and forgings) finished material and welds regardlessmaintenance testing.
1.4 This guide describes the use of the following magnetic
particle method techniques.1.4.2 Wet magnetic particle (see 8.5) 1.4.1 Dry magnetic powder (see 8.4) 1.4.3 Magnetic slurry/paint magnetic particle (see 8.5.7) and
1.1.1 This guide is intended as a reference to aid in thepreparation of specifications/standards procedures and tech- niques.
1.4.4 Polymer magnetic particle (see 8.5.8).
1.5 Persomel Quclificrion-Personnel perfoming examinations in accordance with this guide should be qualified and certified in accordance with ASNT Remended Practice No.SNT-TC-1A ANSI/ASNT Standard CP-189 NAS 410 or as specified in the contract or purchase order.
1.2 This guide is also a reference that may be used asfollows:
1.2.1 To establish a means by which magnetic particletesting procedures remended or required by individualorganizations can be reviewed to evaluate their applicability and pleteness.
1.6 Nondestructive Testing AgencyIf a nondestructivetesting agency as described in Specification E543 is used to perform the examination the nondestructive testing agencyshould meet the requirements of Specification E543.
nel concermed in magnetic particle testing. 1.2.2 To aid in the organization of the facilities and person-
the examination of materials and parts. This guide describes 1.2.3 To aid in the preparation of procedures dealing withmagnetic particle testing techniques that are remended fors og go ss p is go a e and widely varying examination requirements. Since there aremany acceptable differences in both procedure and technique the explicit requirements should be covered by a writtenprocedure (see Section 21).
regarded as standard. The values given in parentheses are 1.7 UnizsThe values stated in inch-pound units are to bemathematical conversions to SI units that are provided for information only and are not considered standard.
1.8 Warning-Mercury has been designated by many regu-latory agencies as a hazardous material that can cause serious medical issues. Mercury or its vapor has been demonstratedto be hazardous to health and corrosive to materials. Cautionshould be taken when handling mercury and mercury contain- ing products. See the applicable product Safety Data Sheetselling mercury or mercury containing products or both into (SDS) for additional information. Users should be aware thatyour state or country may be prohibited by law.
1.3 This guide does not indiente suggest or speify aecep-tance standards for parts/pieces examined by these techniques.It should be pointed out however that after indications have been produced they must be interpreted or classified and thenevaluated. For this purpose there should be a separate code specification or a specific agreement to define the type size location degree of alignment and spacing area concentration
safery concerns if any associated with its ase. lr is the 1.9 This standard does not purport to address oll of theresponsibiliry of the user of this standard to establish appro- priate sofety heaith and environmental practices and deter-mine the applicability of regulatory limitations prior to use.
dance with internationally recognized principles on stondord- 1.10 This intermarionol standard was devefoped in accor-ization established in the Decision on Principles for the
2.3 ASNT Docaments:SNT-TC-1A Personnel Qualification and Certification in Nondestruetive TestingCP-189 ASNT Qualification and Certification of Nonde-2.4 Federal Standards-6 structive Testing PersonnelA-A-59230 Fluid Magnetic Particle Inspetion SuspensionFED-STD-313 Material Safety Data Sheets Preparation and the Submission of2.5 OSHA Docuoment:? 29 CFR 1910.1200 Hazard Communication2.6 AIA Docaments:NAS 410 Nondestructive Testing Personnel Qualification and Certification2.7 ISO Standard:ISO 7810 Identification Cards-Physical Characteristics
Development of Intermational Standards Guides and Re-menclarions issued by the World Trade Organizarion TechunicalBarriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:?
D93 Test Methods for Flash Point by Pensky-MartensD445 Test Method for Kinematic Viscosity of Transparentand Opaque Liquids (and Calculation of Dynamic Viscos- ity)E165/E165M Practice for Liquid Penetrant Testing for Gen- eral IndustryE543 Specification for Agencies Performing Nondestructive TestingE1316 Terminology for Nondestructive ExaminationsE1444/E1444M Practice for Magnetic Particle Testing E3024/E3024M Practice for Magnetic Particle Testing for2.2 SAE: Aerospace Meterials Speifcations:4 General IndustryAMS 2300 Premium Aircraft Quality Steel CleanlinessAMS 2301 Aircraft Quality Steel Cleanliness Magnetic Par- Magnetic Particle Inspection ProcedureAMS 2303 Aircraft Quality Steel Cleanliness Martensitic ticle Inspection ProcedureCorrosion Resistant Steels Magnetic Particle Inspection ProcedureAMS 2641 Vehicle Magnetic Particle InspectionAMS 3040 Magnetic Particles Non-fluorescent Dry MethodAMS 3041 Magnetic Particles Method. Oil Vehicle Ready to Use Non-fluorescent AMS 3042 Magnetic Particles Non-fluorescent Method. Dry Powder WetAMS 3043 Magnetic Particles Non-fluorescent Oil Vehicle.AMS 3044 Magnetic Particles Fluorescent Wet Method. Aerosol PackagedAMS 3045 Magnetic Particles. Non-luorescent V Dry Powder WetAMS 3046 Magnetic Particles Non-fluorescent Method. Oil Vehicle Ready to Use 10MMethod Oil Vehicle Aerosol PackagedAMS 5062 Steel Low Carbon Bars Forgings. Tubing. Sheet. Strip and Plate 0.25 Carbon MaximumAMS 5355 Investment Castings AMS-I-83387 Inspection Process Magnetic RubberAS 4792 Water Conditioning Agents for Aqueous Magnetic Particle InspectionAS 5282 Tool Steel Ring Standard for Magnetic ParticleAS 5371 Reference Standards Notched Shims for Magnetic InspectionParticle Inspection
3. Terminology
Terminology E1316. 3.1 For definitions of terms used in the practice refer to
4. Summary of Guide
4.1 Principle-The magnetic particle method is based onestablishing a magnetic field with high flux density in a ferromagnetic material. The flux lines must spread out whenthey pass through non-ferromagnetic material such as air in athis spreading action may force some of the flux lines out of the discontinuity or an inclusion. Because flux lines can not cross s material (flux leakage). Flux leakage is also caused by reduc-is strong enough fine magnetic particles will be held in place dimensional change or the end of the part If the flux leakageand an accumulation of particles will be visible under theproper lighting conditions. While there are variations in the magnetic particle method they all are dependent on thislocations of magnetic flux leakage. The amount of fux leakage principle that magnetic particles will be retained at theat discontinuities depends primarily on the following factors: flux density in the material and size orientation and proximityto the surface of a discontinuity. With longitudinal fields all of the ffux lines must plete their loops though air and anexcessively strong magnetic field may interfere with examina-flux-density present at these points. tion near the flux entry and exit points due to the high
4.2 MerhodWhile this practice permits and describesmany variables in equipment materials and procedures thereare three steps essential to the method:
4.2.1 The part must be magnetized.
contract/purchase order/specification should be applied while 4.2.2 Magnetic particles of the type designated in thethe part is magnetized or immediately thereafter.
4.2.3 Any accumulation of magnetic particles must beobserved interpreted and evaluated.
4.3 Magnetization:
4.3.1 Ways to Magnetize-A ferromagnetic material can bemagnetized either by passing an electric current through the material or by placing the material within a magnetic fieldoriginated by an external source. The entire mass or a portionof the mass can be magnetized as dictated by size and equipment capacity or need. As previously noted in order to bethe magnetic field lines. If a discontinuity is open to the detectable the discontinuity must interrupt the normal path ofsurface the ffux leakage attracting the particles will be at thesame discontinuity is below the surface fux leakage evident maximum value for that particular discontinuity. When thaton the surface will be a lesser value.
4.3.2 Field DirecrionIf a discontinuity is oriented parallelto the magnetic field lines it may be essentially undetectable. Therefore since discontinuities may occur in any orientation itmay be necessary to magnetize the part or the area of interesttwice or more sequentially in different directions by the same method or a bination of different methods (see Section 13)to induce magnetic field lines in a suitable direction in which to perform an adequate examination.
cient strength to indicate those discontinuities which are 4.3.3 Field StrengthThe magnetic field must be of suffi-unacceptable yet must not be so strong that an excess of localparticle accumulation masks relevant indications (see Section 14).
various types of magnetic particles available for use in mag- 4.4 Types of Magnetic Particles and Their UseThere arenetic particle testing. They are available as dry powders(fluorescent and nonfluorescent) ready for use as supplied (see 8.4) powder concentrates (fluorescent and nonfluorescent) fordispersion in water or suspending in light petroleum distillates
(see 8.5) magnetic slurries/paints (see 8.5.7) and magneticpolymer dispersions (see 8.5.8).
examined has been properly magnetized the magnetic particles 4.5 Evalucrion of IndicarionsWhen the material to beXadod saped ssax a pue pde padod uaq ae removed there will be accumulations of magnetic particlesremaining at the points of flux leakage. These accumulationsshow the distortion of the magnetic field and are called indications. Without disturbing the particles the indicationsmust be examined classified pared with the acceptance standards and a decision made concerning the disposition ofthe material that contains the indication.
4.6 Typical MagneticParticle Indications:
4.6.1 Surface DisconriririesSurface discontinuities withfew exceptions produce sharp. distinct pattems (see Annex A1).
4.6.2 Near-suerface Discontinarities-Near-surface discontisurface. The patterns tend to be broad rather than sharp andthe particles are less tightly held (see Annex A1).
5. Significance and Use
5.1 The magnetic particle method of nondestructive testingindicates the presence of surface and near-surface discontinui-ties in materials that can be magnetized (feromagnetic). This method can be used for production examination of parts/ponents or structures and for field applications where portability of equipment and accessibility to the area to bediscontinuities can be enhanced by using fuorescent particles examined are factors. The ability of the method to find smallfield of the proper strength whose orientation is as close as suspended in a suitable vehicle and by introducing a magneticpossible to 90° to the direction of the suspected discontinuity(see 4.3.2). A smoother surface or a pulsed current improves mobility of the magnetic particles under the influence of themagnetic field to collect on the surface where magnetic flux leakage occurs.
6. Equipment
6.1 TypesThere are a number of types of equipmentavailable for magnetizing ferromagnetic parts and ponents.
FIG. 1 (a) Articulating Yoke Method of Part Magnetization
With the exception of a permanent magnet all cquipmentrequires a power source capable of delivering the requireddictates the sizes of cables and the capability of relays current levels to produce the magnetic field. The current usedalternating current. switching contacts meters and rectifier if the power source is
6.2 Portabiliry-Portability which includes the ability tohand carry the equipment can be obtained from yokes portable coils with power supplies and capacitor dischargepower supplies with cables. Generally portable coils provide s o su sn q s u pensate for their lower current flow. Capacitor discharge units use high current storage capacity and provide these highcurrent levels for only a very short duration.
which induce a magnetic field between the poles (legs) and are 6.3 YokesYokes are usually C-shaped electromagnetsused for local magnetization (Fig. I(a). Many portable yokeshave articulated legs (poles) that allow the legs to be adjusted to contact irregular surfaces or two surfaces that join at anangle.
6.3.1 Permanent MagnersPermanent magnets (Fig. 1(b))deqqe tions. This restriction may be due to application impracticality or due to the specifications governing the examination. Perma-nent magnets can lose their magnetic field generating capacity by being partially demagnetized by a stronger flux field beingdamaged or dropped In addition the particle mobility created by AC current or HW current pulsations produced by electro-magnetic yokes are not present. Particles steel ilings chips and scale clinging to the poles can create a housekeepingproblem.
2. The prod tips that contact the piece should be aluminum. 6.4 ProdsProds are used for local magnetizations see Fig.copper braid or copper pads rather than solid copper. With solid copper tips accidental arcing during prod placement orp ons o uod ddo u eao
FIG. 1 (b) Permanent Magnet Yoke Method of Part Magnetization(penuguoo)
may result in metallurgical damage (softening hardening.cracking etc.). Open-circuit voltages should not exceed 25 V.
which may be built into the prod handles should be provided 6.4.1 Remote Control SwitchA remote-control switch to permit the current to be turned on after the prods have been properly placed and to tum it off before the prods are removedin order to prevent arcing (arc burns).
3. The unit normally is furnished with a head/tailstock bi- 6.5 Bench Unit--A typical bench type unit is shown in Fig.nation along with a fixed coil (see Fig. 4).
nently mounted or fixed and used to examine parts should be 6.6 UV-A Lamps which are portable hand-held perma-checked for output at the verification intervals specified in Table 2 and after bulb or filter replacement. A longer periodmay be used if a plan justifying this extension is prepared byis 1000 μW/cm² at the examination surface. the NDT facility or its delegate. Minimum acceptable intensity
voltage greater than ± 10 % can cause a change in outpt and consequen- u u auq e dum as ode Amu e 3usn uMI 30used where there is evidence of voltage changes greater than 10 %. tial loss of inspection perfomance. A constant voltage transformer may be
6.6.1 UV-A lamps that use a UV-A LED source shallproduce a peak wavelength at 360 to 370 nanometers as measured with a spectroradiaometer. When requested themanufacturer shall provide a certification thereof.
6.6.2 Battery-powered UV-A lamps used to examine partsshall have their intensity measured prior to use and after eachuse.
6.7 Equipmenr Verification-See Section 20.
7. Examination Area
7.1 UV-A Intensiry for ExaminarionMagnetic indicationsfound using nonfluorescent particles are examined under vis-examined under UV-A irradiance. This requires a darkened ible light. Indications found using fluorescent particles must bearea with apanying control of the visible light intensity.
7.1.1 Vsible Light IntensiryThe intensity of the visiblelight at the surface of the part/work piece undergoing nonfuo-of 100 foot candles (1076 lux). rescent particle examination is remended to be a minimum
using nonfluorescent particles visible light intensities as low as 7.1.1.1 Field Examinations-For sone field examinations50 foot candlles (538 lux) may be used when agreed on by the contracting agency.
7.1.1.2 Ambienr Visible LighrThe intensity of ambientvisible light in the darkened area where fluorescent magnetic particle testing is performed is remended to not exceed 2foot candles (21.5 lux).
7.1.2 UV-A Irradiance:
7.1.2.1 UV-A ImrensiryThe UV-A irradiance at the exami-μW/em* when measured with a suitable UV-A radiometer. nation surface is remended to not be less than 1000
bulb allow the UV-A lamp to warm up for a minimum of five d d A 1ultraviole light UV-A emitted. When using LED UV-A lamps minutes prior to its use or measurement of the intensity of the
Typical portable power pack for prods
Typical Double Prod SetFIG. 2 Prods
Typical Single Prod Set
prior to examining parts under UV irradiance. (Warning-Photochromic or permanently tinted lenses should not be worn during examination.)
7.2 Housekeeping-The examination area should be keptfree of interfering debris. If fluorescent materials are involved the area should also be kept free of fluorescent objects notrelated to the part/piece being examined.
8. Magnetic Particle Materials
8.1 Magnetic Particle Properties:
8.1.1 Dry Parricle Properties-AMS 3040 describes thegenerally accepted properties of dry method particles.
describe the generally accepted properties of wet method 8.1.2 Wer Particle ProperriesThe following documentsparticles in their various forms:
FIG. 3 Bench Unit
AMS 3041 Magnetic Particles Non-fluorescent WetMethod Oil Vehicle Ready to Use
Method Dry Powder AMS 3042 Magnetic Particles Non-fluorescent Wet
it is remended to allow the lamp to stabilize in accordance with the manufacturer’s remendations prior to use ormeasurement.
Vehicle Aerosol Packaged AMS 3043 Magnetic Particles Non-fluorescent Oil
7.1.3 Dark Area Eye AdaptationThe generally acceptedpractice is that an inspector be in the darkened area at least one(1) minute so that his or her eyes will adapt to dark viewing
AMS 3044 Magnetic Particles Fluorescent Wet Method Dry Powder
