1、Designation: E 1158 04Standard Guide forMaterial Selection and Fabrication of Reference Blocks forthe Pulsed Longitudinal Wave Ultrasonic Examination ofMetal and Metal Alloy Production Material1This standard is issued under the fixed designation E 1158; the number immediately following the designati
2、on indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers general procedur
3、es for the materialselection and fabrication of reference blocks made of metal ormetal alloys and intended to be used for the examination of thesame or similar production materials by pulsed longitudinalultrasonic waves applied perpendicular to the beam entrysurface. Primary emphasis is on solid mat
4、erials but some of thetechniques described may be used for midwall examination ofpipes and tubes of heavy wall thickness. Near-surface resolu-tion in any material depends upon the characteristics of theinstrument and search unit employed.1.2 This guide covers the fabrication of reference blocks foru
5、se with either the immersion or the direct-contact method ofultrasonic examination.1.3 Reference blocks fabricated in accordance with thisguide can be used to determine proper ultrasonic examinationsystem operation. Area-amplitude and distance-amplitudecurves can also be determined with these refere
6、nce blocks.1.4 This guide does not specify reference reflector sizes orproduct rejection limits. It does describe typical industryfabrication practices and commonly applied tolerances wherethey lend clarity to the guide. In all cases of conflict betweenthis guide and customer specifications, the cus
7、tomer specifica-tion shall prevail.1.5 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and to determine the applicability of regula-tory limitations
8、 prior to use.2. Referenced Documents2.1 ASTM Standards:2E 127 Practice for Fabricating and Checking AluminumAlloy Ultrasonic Standard Reference Blocks3E 428 Practice for Fabrication and Control of Steel Refer-ence Blocks Used in Ultrasonic ExaminationE 1316 Terminology for Nondestructive Examinatio
9、ns3. Terminology3.1 DefinitionsFor definitions of terms used in this guide,see Terminology E 1316.4. Summary of Guide4.1 This guide describes a method of selecting suitablereference block material from current or previous productionand the subsequent fabrication and checking of the resultingultrason
10、ic reference blocks.5. Significance and Use5.1 This guide is intended to illustrate the fabrication ofultrasonic reference blocks that are representative of theproduction material to be examined. Care in material selectionand fabrication can result in the manufacture of referenceblocks that are ultr
11、asonically similar to the production materialthus eliminating the reference block as an examination vari-able.6. Material Selection6.1 It is good practice to use a sample removed from theproduction lot of material as the reference block material.When this is not possible the following guidelines sho
12、uld befollowed.6.2 The reference block material should be of the samegeneral shape and dimensions, surface finish, chemical com-position, and microstructure as the production material to beexamined.6.3 To ensure that the material chosen is suitable for use asreference block material and is free of p
13、otentially interfering1This guide is under the jurisdiction of ASTM Committee E07 on Nondestruc-tive Testing and is the direct responsibility of Subcommittee E07.06 on UltrasonicMethod.Current edition approved February 1, 2004. Published March 2004. Originallyapproved in 1990. Last previous edition
14、approved in 1998 as E 1158 - 98.2For 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 website.3The reference blocks in Prac
15、tice E 127 are used to check the performance ofultrasonic examination equipment and for standardization and control of ultrasonicexaminations of aluminum alloy products. The ultrasonic response of the blocks inPractice E 127 is evaluated against a standard target. The blocks described in thisstandar
16、d are used for the examination of production material and may be used toestablish accept-reject criteria.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.reflectors, ultrasonically examine the reference block materialat the anticipate
17、d examining frequency and at a sensitivity thatproduces an acoustic noise level of 20 % screen height. Theentire block should be scanned from the surface which will beused for standardization. Any discrete indication that exceeds40 % screen height should be cause to remove the materialfrom considera
18、tion as an ultrasonic reference block.6.4 Reference block material that meets the guidelines of6.3 should then be examined at a sensitivity that producesmultiple reflections from the back surface (between 3 and 5reflections in most metals and metal alloys). The productionmaterial should be examined
19、at the same sensitivity level todetermine that the same number of back reflections areobtained. This procedure may have to be repeated several timesand an average number of back reflections determined in thecase of some materials (see Note 1).NOTE 1In some highly attenuative materials more than one
20、or twoback reflections may not be attainable. In these cases, selection of thereference block material may be based on similar acoustic noise levelsfrom both the production material and that chosen for a reference block.7. Reference Block Configuration7.1 There are many different types of reference
21、blocks usedin industry depending upon the size and shape of the materialto be examined. Some of the more common types are describedin 7.2 through 7.7, and shown in Figs. 1-7. An alternate methodfor fabricating flat-bottom holes is described in the annex.7.2 Fig. 1 shows the typical reference standar
22、ds used forultrasonic examination when the product to be examinedconsists of large round bar stock, between 1 and 10 in. indiameter. With such products it is often necessary to correct forthe loss of signal with increasing examination distance(distance-amplitude-correction, or DAC). Therefore, a ste
23、ppedblock, as shown in Fig. 1 is commonly used. This type of blockis typically referred to as a distance-amplitude-block. It con-tains a number of holes of the same size at various distancesfrom the scan surface. A typical flat-bottom hole size found inmany such blocks is564 in. or larger depending
24、upon theultrasonic attenuation, or the internal structure of the product,or both. For even larger diameter bars the distance amplitudecorrection reference standard may contain even larger flatbottom holes, possibly14 in. or greater.7.3 To determine the linearity of the examination and toestablish th
25、e quality level of the large-diameter product, (7.2),an area-amplitude reference block as shown in Fig. 2 iscommon. An area-amplitude-block contains holes of differentcrossectional areas placed at the same distance from the scansurface. Typical hole sizes range from between264 and864 in.0.79 and 3.1
26、8 mm with even larger flat-bottom holes used inreference blocks intended for use for the largest bars.7.4 For small round bar stock, typically 1 in. 25.4 mm andunder, a distance-amplitude block is normally not required. Thetypical area-amplitude block for this product is the same as forthe larger di
27、ameter material as shown in Fig. 2, but on a smallerscale. The hole sizes typically range from between264 and564in. 0.79 and 1.98 mm for many metal and metal alloyproducts.7.5 When the product to be examined consists of largesquare or rectangular bar stock, the distance-amplitude refer-ence block is
28、 often of the type shown in Fig. 3. The typicalarea-amplitude reference block is shown in Fig. 4. The refer-ence block hole sizes are typically the same as those used forsimilar thickness round bars.7.6 The smaller sizes of square or rectangular bar stock, 1in. 25.4 mm and under in the direction of
29、examination, oftendo not require the use of a distance-amplitude reference block.The area-amplitude block may be similar to that shown in Fig.4. The reference block hole sizes are usually similar to thoseused for round bars of the same thickness.7.7 The reference blocks used for the ultrasonic exami
30、na-tion of products with more complex geometries are normallyfabricated from production samples so that the effects ofgeometry variations are minimized.NOTE 1All holes are the same diameter.FIG. 1 Typical Distance-Amplitude Reference Block Configurationfor the Ultrasonic Examination of Large Metal a
31、nd Metal AlloyBars of from 1 to 10 in. 25.4 to 254.0 mm Diameter and LargerNOTE 1Holes are of different diameters.FIG. 2 Typical Area-Amplitude Reference Block for use inUltrasonic Examination of Round Bars as in Fig. 1NOTE 1All holes are the same diameter.FIG. 3 Typical Distance-Amplitude Reference
32、 Block for theUltrasonic Examination of Large Square or Rectangular BarsGreater than 1 in. 25.4 mmNOTE 1Holes are of different diameters.FIG. 4 Typical Area-Amplitude Reference Block for the UltrasonicExamination of Square or Rectangular BarsE11580428. Fabrication Procedure8.1 Specific fabricating p
33、rocedures are dependent upon theconfiguration of the reference block, the block composition, theexamination criticality, and even the skill of the machinists.Some general guidelines are given in 8.2 through 8.3.2.8.2 Flat-Bottom HolesFlat-bottom holes (FBHS) shouldbe drilled such that the hole botto
34、m is perpendicular to theexamining sound beam. For the fabrication of reference stan-dards of the types shown in Figs. 1-4, a common procedureinvolves the drilling of the chosen hole sizes to a desired depthusing a conventional fluted drill bit. In Fig. 1 this depth wouldbe34 in. 19.05 mm. The flute
35、d drill bit, or another of the samesize, is carefully ground to remove the point and square the tip.An optical comparator or tool makers microscope is useful todetermine when the point has been completely removed andthe drill bit end is flat and square.8.2.1 The flattened drill bit is then used to c
36、arefully flattenthe bottom of the drilled hole. This operation normally requiresgreat care to avoid drill breakage while still ensuring that thehole bottom is flat. A physicians ear examination microscopewith a tip of the proper diameter is helpful in determining whenthe hole bottom is truly flat.8.
37、2.2 If the ultrasonic examination is to be conducted withthe product (and therefore the reference block) immersed in aliquid, it is considered good practice to plug the flat-bottomholes in the reference block. Before plugging the holes it isimportant that the holes be free of debris and totally dry.
38、Moisture, metal shavings, or both, can influence the ultrasonicresponse from the hole bottom.8.2.3 When using metal plugs, counterbores are machinedin the block to seat the plugs. An alternative method is to useplastic or rubber type sealant forced a short distance into theholes and allowed to harde
39、n.8.3 Diffusion Bonding MethodThe diffusion bondingtechnique offers an alternative method of reference blockmanufacture. With this method it is possible to fabricatereference blocks containing flat disc-shaped ultrasonic reflec-tors instead of flat-bottom holes. In many cases this permits theexamina
40、tion of the reference block from more than onedirection thus enhancing the utility of the block.8.3.1 A typical example is shown in Fig. 5. A diffusion-bonded reference block for small diameter rounds could befabricated as shown. A section is removed from one of theround bars to be examined. The bar
41、 section is split lengthwiseand both split surfaces are carefully ground. An endmill of thedesired diameter is used to mill a shallow (typically12 the holediameter in depth) flat-bottom hole in one of the split sections.The sections are then bonded back together using the diffusionbonding process. (
42、The application of heat and pressure on thetwo sections for a period of time results in a sound diffusionbond which is indistinguishable metallographically or ultra-sonically from the normal structure.) (See Note 2.) The resultis a reference standard that can be examined from either of 2sides.NOTE 2
43、The time, temperature, and pressure requirements for adiffusion bond are both material and configuration dependent and there-fore are beyond the scope of this guide. The American Welding Society4can furnish information on the subject.8.3.2 With developed skills, all of the reference blocksshown in F
44、igs. 1-4 along with many more types can besuccessfully fabricated using the diffusion bonding technique.4Available from The American Welding Society (AWS), 550 NW LeJeune Rd.,Miami, FL 33126.NOTE 1The finish and fitup of the mating surfaces strongly influencethe success of the bond.FIG. 5 Typical Ex
45、ample of a Diffusion Bonded Reference Blockfor Small Diameter Round BarsNOTE 1The shape of the curve may differ as discussed in 10.1.FIG. 6 Typical Distance-Amplitude Ultrasonic Response CurveFIG. 7 Typical Area-Amplitude Ultrasonic Response CurveE11580439. Verification of Reflector Acceptability9.1
46、 It is often desirable or required by specification, or both,that the flat-bottom holes be proven to be of the proper size andflatness. A hole replication method is often used to measurethese hole characteristics. This method, more often used forholes of364 in. 1.19 mm or greater diameter, involves
47、forcinga liquid rubber or plastic compound into the clean, dry hole,removing all entrapped air. When the material hardens it can beremoved in the form of a plug or replica. This plug or holereplica can then be examined for the proper size and flatness.The removal of the hardened plug is facilitated
48、if a small wireor other object is inserted into the hole while the replicatingmaterial is still liquid. When the replicating material solidifiesthe wire serves as a handle permitting easy removal of the plug.9.2 Replication of the disc-shaped reflector in diffusionbonded reference blocks is not poss
49、ible. An alternative methodof determining whether the reflector has been distorted by thebonding process is to fabricate a second block under identicalconditions for destructive examination at the conclusion of theprocess.10. Ultrasonic Response Characteristics10.1 If the fabrication procedure, either drilling or diffusionbonding, was sufficiently accurate, then the distance amplitudereference block set may yield an ultrasonic response curvesimilar to that shown in Fig. 6. The shape of the curve maydiffer significantly with any change of test freq
