SAE J 427-1991 Penetrating Radiation Inspection《穿透辐射检验》.pdf

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1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro

2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (412) 772-8512 FAX: (412) 776-0243TO PLACE A DOCUMENT

3、 ORDER; (412) 776-4970 FAX: (412) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1991 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001INFORMATIONREPORTAn American National StandardJ427REV.MAR91Issued 1960-0

4、6Revised 1991-03Superseding J427 DEC88(R) PENETRATING RADIATION INSPECTIONForewordThis Document has not changed other than to put it into the new SAE Technical Standards BoardFormat.1. ScopeThe purpose of this SAE Information Report is to provide basic information on penetrating radiation,as applied

5、 in the field of nondestructive testing, and to supply the user with sufficient information so that hemay decide whether penetrating radiation methods apply to his particular inspection need. Detailedinformation references are listed in Section 2.2. References2.1 Applicable PublicationsThe following

6、 publications form a part of this specification to the extent specifiedherein. The latest issue of SAE publications shall apply.2.1.1 ASTM PUBLICATIONSAvailable from ASTM, 1916 Race Street, Philadelphia, PA 19103ASTM E 94Recommended Practice for Radiographic TestingASTM E 545Standard Method for Dete

7、rmining Image Quality in Thermal Neutron Radiographic Testing2.2 Related PublicationsThe following publications are provided for information purposes only and are not arequired part of this document.2.2.1 ASM PUBLICATIONATTN: MSC/Book Order, ASM International, PO Box 473, Novelty, OH 44072-9901.Meta

8、ls Handbook, Vol. 17, 1989, pp. 295357. 2.2.2 ASME PUBLICATIONAvailable from ASME, 345 East 47 Street, New York, NY 10017-2330.“ASME Boiler and Pressure Vessel Code.“ 2.2.3 ASTM PUBLICATIONSAvailable from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959ASTM E 142, “Controlling Quality o

9、f Radiographic Testing.“ ASTM E 545 “Standard Method for Determining Image Quality in Thermal Neutron Radiographic Testing.“ ASTM E 748 “Standard Practice for Thermal Neutron Radiography of Materials.“ H. Berger, ed., “Practical Applications of Neutron Radiography and Gaging,“ ASTM STP 586. SAE J427

10、 Revised MAR91-2-2.2.4 OTHER PUBLICATIONSNondestructive Testing Handbook, Vol. 3, Radiography and Radiographic Testing, 1985, American Societyfor Nondestructive Testing, Columbus, OH 43228Tool and Manufacturing Engineers Handbook, Vol. 4, Quality Control Assembly, 1987, Society ofManufacturing Engin

11、eers, Dearborn, MI 48121“Radiography in Modern Industry.“ Eastman Kodak Co., Rochester, NY, 1969.John R. Bradford, ed., “Radioisotopes in Industry.“ 1953.R. C. McMaster, ed., Nondestructive Testing Handbook, Vol. I, Section 1327, 1959. American Society ofNondestructive Testing, Columbus, OH 43321.H.

12、 Berger, Neutron Radiography. New York: American Elsevier Publishing Co., 1965.W. J. McGonnagle, Nondestructive Testing. New York: McGraw-Hill Book Co., 1961.R. Halmshaw, ed., Industrial Radiology Techniques. New York: American Elsevier Publishing Co., 1971.E. T. Clarke, “Gamma Radiography of Light

13、Metals.“ Nondestructive Testing, Vol. 16, May-June 1958, p.265.“Qualification and Certification of Personnel.“ Recommended Practice No. SNT-TC-1A, Supplement A(Radiography), American Society for Nondestructive Testing, Columbus, OH 43328.Justin G. Schneeman, Industrial X-Ray Interpretation. Evanston

14、, IL: Intex Publishing Co., 1968.“Radiographic Testing.“ Programmed Instruction Handbook PI-46, Convair Div., General DynamicsCorp., 1967.AMS 2635 C “Radiographic Inspection.“ July 15, 1981.“Military Standard InspectionRadiographic.“ MIL-STD-453, U.S. Department of Defense.M. R. Hawkesworth, ed., “R

15、adiography with Neutrons,“ British Nuclear Energy Society, London, 1975.“Neutron Radiography Issue, Atomic Energy Review, Vol. 15, No. 2, International Atomic Energy Agency,Vienna, 1977.3. GeneralPenetrating radiation is a versatile nondestructive test method used in modern industry. The use ofpenet

16、rating x-rays, gamma rays, thermal neutrons, and other forms of radiation which do not affect the materialbeing inspected, provide the basic information by which soundness can be determined. Radiography providesa permanent record on film of internal conditions. Fluoroscopy differs from radiography i

17、n that the radiationimage is projected on a fluorescent screen or other readout monitor and is often observed visually in real timerather than recorded on a film. Systems are available that produce digitally reconstructed, photographic, ormagnetically recorded displays. Penetrating radiation enables

18、 industry to monitor a variety of products for anumber of types of imperfections. Objects inspected range in size from microminiature electronic parts to verylarge components in a wide range of manufactured forms (for example, castings, weldments, assemblies).4. PrinciplesX-rays, gamma rays, and neu

19、trons possess the capability of penetrating materials, even thosethat are opaque to light. In passing through matter, some of these rays are absorbed or scattered. Materialsabsorb x-rays and gamma rays in proportion to their mass. Neutron absorption, on the other hand, is notrelated proportionally t

20、o atomic number or mass; neighboring elements can differ in neutron absorption byfactors of 100 or more. Differential absorption of the radiant energy passing through the object due to thepresence of voids, discontinuities, or density variations caused by inhomogeneity or internal construction isrec

21、orded on radiographic film or observed directly by fluoroscopic methods. With acceptable conditions oftechnology and equipment, it is generally agreed that discontinuities can be detected which present to the axisof radiation a minimum dimension of 1 to 2% of the thickness of the object undergoing r

22、adiographicexamination, or 2 to 6% for fluoroscopic examination. Two-dimensional imperfections, such as cracks and coldshuts, are not detectable unless they present an effective thickness difference of the above magnitude, orgreater, and are in appropriate alignment with the beam of radiation.SAE J4

23、27 Revised MAR91-3-5. Procedure5.1 Radiographic Film TechniqueA radiographic film is a photographic record produced by the passage of x-rays, gamma rays, or neutrons through an object onto a film. When film is exposed to a radiation source orlight, an invisible change is produced in the film emulsio

24、n. The areas so exposed become dark when the film isimmersed in a developing solution; the amount of darkening depends upon the degree of exposure. Imageformation is usually enhanced through use of thin metal screens in intimate contact with the film. Lead screensare used in x-ray exposures made wit

25、h energy above 100 kV and in gamma ray exposures. Screens arenecessary for film detection of thermal neutrons. Gadolinium metal screens are normally used for direct-exposure techniques and indium metal screens are normally used for indirect-exposure techniques. Thedeveloping, fixing, and washing of

26、exposed film may be done either manually or in an automatic film processor.The exposed, processed, and dried radiographic film is examined under transmitted light. Interpretation of theimage is performed in accordance with established codes, specifications, or acceptance criteria.The finished radiog

27、raph should be viewed under conditions which provide for the best visualization of detailcombined with maximum comfort and minimum fatigue for the observer. A high-intensity illuminator withadjustable intensity is almost a necessity for optimum radiographic observation and interpretation.Penetramete

28、rs are used to indicate the image quality which exists in a radiograph. The type generally used inthe United States is a small rectangular plate of the same material as the object being x-rayed. It is uniform inthickness (usually 2% of the object thickness) and has holes drilled through it. ASTM spe

29、cifies hole diameters1, 2, and 4 times the thickness of the penetrameter. Step, wire, and bead penetrameters are also used. (SeeASTM E 94.) For neutron radiography, image quality indicators provide a measure of the relative exposure dueto gamma rays, higher energy neutrons, and scattered neutrons. A

30、dditional image quality indicators aresuggested to provide measures of contrast and resolution capability. (See ASTM E 545.)5.1.1 ADVANTAGESFilm radiography provides a permanent, visible record of the internal condition of the subject.Preservation of films is a common practice in industry.5.1.2 DISA

31、DVANTAGESHigh cost is the chief objection to film radiography. One-half of the average inspection costmay be the radiographic film cost. X-ray paper products reduce this disadvantage when maximumperformance capability is not required.Inspection results are not available until radiographic film has b

32、een exposed, processed, and interpreted.5.2 Fluoroscopic Inspection TechniqueFluoroscopy is the process of examining an object by direct or indirectobservation of the fluorescence of a screen caused by radiation transmitted through an object. Thearrangement of the x-ray source, object, and imaging p

33、lane is identical to that used in radiography. Thefluorescent screen, image intensifier tube, television camera, and similar electronic imaging devices convert x-ray to visible light for further signal processing, operator interpretation, and recording.5.2.1 ADVANTAGESProduction line inspection syst

34、ems are available. These can result in low cost per partinspected and can meet the inspection requirements of high-volume production. Real-time imageenhancement and interpretation are available in systems using television imaging.5.2.2 DISADVANTAGESThe sensitivity of the fluoroscopic process is not

35、usually as great as that of radiography, 2to 6% being routine. The additional cost of producing a permanent record of the examination may be adisadvantage. For systems employing television imaging, however, magnetic recording can be used,photographs may be taken of the television image, or digital p

36、rocessing can be used for imaging andinterpretation.6. ApplicationThe ability of high energy radiation to penetrate all engineering materials and the differentialrates of absorption for different materials are responsible for the extensive use of this nondestructive inspectiontechnique throughout in

37、dustry. Accordingly, penetrating radiation inspection methods are extensively used forflaw detection in the following areas:SAE J427 Revised MAR91-4-6.1 CastingsThe widespread use of penetrating radiation methods for the inspection of castings results from thefact that most of the flaws and disconti

38、nuities inherent in ferrous and nonferrous castings can be readilydetected by this inspection medium. Shrinkage, gas porosity, inclusions, hot tears, cracks, cold shuts, coreshifts, and major surface irregularities may be detectable by radiographic or fluoroscopic inspection techniques.In addition,

39、the following discontinuities which are peculiar to light metal (aluminum and magnesium) castingsare detectable: gas holes, dross inclusions, segregation, microshrinkage, hydrogen porosity, microporosity,shrinkage, sponge, cold shuts, and other discontinuities common to light metal castings.6.2 Weld

40、mentsPenetrating radiation inspection of weldments is a widely accepted procedure for the detection ofinternal discontinuities. It is used in the establishment of welding procedures to qualify welders and especiallyto control quality of welded joints in finished products. The following imperfections

41、 or discontinuities aredetectable by radiography: porosity, cracks, incomplete penetration and fusion, inclusions, and otherdiscontinuities common in welded joints.6.3 Finished AssembliesPenetrating radiation techniques are applicable to the inspection of fabricatedassemblies relative to placement o

42、f internal components, such as electronic devices, mufflers, fuel tanks,bonded honeycomb, and tires. Electrical connections as well as the position of bolts and nuts in finishedenclosures are frequently checked by radiography. Neutron radiography of assemblies provides a capability toverify proper p

43、lacement of hydrogen-containing materials in metal assemblies. By this method rubberO-Rings, plastic parts, propellants, fluid levels, and similar materials can be visualized even when theseobjects are inside metallic containers.6.4 Miscellaneous ApplicationsOccasional use is made of radiographic te

44、chniques in the inspection offorgings, powder metal parts, and of nonmetallic materials such as plastic, rubber, ceramic, and solidpropellant. The limited use of this inspection medium for forgings is explained by the fact that forging defectsare smaller in size and unsuitably oriented for reliable

45、detection by radiography.7. EquipmentThere are a number of factors which affect the use of penetrating radiation to varying extents.These factors can be grouped into three general categories as follows:a. Source of radiationb. Object or material to be examinedc. Detecting or recording medium.Sources

46、 for neutron radiography include nuclear reactors, accelerators, and radioactive isotopes. Thesesources can be moved (in a truck, for example) but most neutron radiographic inspection is done by bringingthe inspection object to the source. Radiation sources for other types of radiography involve eit

47、her x-raygenerators or one of several radio isotopes. X-rays are produced when high-velocity electrons impinge upontarget atoms. The energy of the x-radiation produced is a function of the velocity of the impinged electrons,which in turn is dependent upon the applied anode voltage (kV or MeV). The p

48、ractical thickness range of steelwhich can be inspected by x-ray units is proportional to their radiation energy, as shown in Figure 1. Theusefulness of Figure 1 can be extended to other materials by referring to Table 1, which gives equivalencefactors for various other materials as compared to stee

49、l.Radiographic isotopes emit radiation at discrete energy levels. The approximate practical thickness range ofthe most commonly used radioisotopes for steel is included in Figure 2. The energy level of the gammaradiation for the two most commonly used isotopes determines the equivalence factor for materials other thansteel (included in Figure 2). Table 1 can be utilized to approximate these equivalence factors by averaging theenergy values for a given source and using the closest energy level column in the table.Other factors such as economics, flexibility, sensi