1、Designation: E23 12aAn American National StandardStandard Test Methods forNotched Bar Impact Testing of Metallic Materials1This standard is issued under the fixed designation E23; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the
2、 year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 These test methods describe
3、notched-bar impact testingof metallic materials by the Charpy (simple-beam) test and theIzod (cantilever-beam) test. They give the requirements for:test specimens, test procedures, test reports, test machines (seeAnnexA1) verifying Charpy impact machines (seeAnnexA2),optional test specimen configura
4、tions (see Annex A3), pre-cracking Charpy V-notch specimens (see Annex A4), designa-tion of test specimen orientation (see Terminology E1823), anddetermining the percent of shear fracture on the surface ofbroken impact specimens (see Annex A4). In addition, infor-mation is provided on the significan
5、ce of notched-bar impacttesting (see Appendix X1), and methods of measuring thecenter of strike (see Appendix X2).1.2 These test methods do not address the problems associ-ated with impact testing at temperatures below 196 C (77 K).1.3 The values stated in SI units are to be regarded asstandard. No
6、other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bilit
7、y of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 5.2. Referenced Documents2.1 ASTM Standards:2B925 Practices for Production and Preparation of PowderMetallurgy (PM) Test SpecimensE177 Practice for Use of the Terms Precision and Bias inASTM Test Method
8、sE604 Test Method for Dynamic Tear Testing of MetallicMaterialsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1823 Terminology Relating to Fatigue and Fracture Test-ingE2298 Test Method for Instrumented Impact Testing ofMetallic Materials3. Summary o
9、f Test Method3.1 The essential features of an impact test are: a suitablespecimen (specimens of several different types are recognized),a set of anvils, and specimen supports on which the testspecimen is placed to receive the blow of the moving mass, amoving mass that has sufficient energy to break
10、the specimenplaced in its path, and a device for measuring the energyabsorbed by the broken specimen.4. Significance and Use4.1 These test methods of impact testing relate specificallyto the behavior of metal when subjected to a single applicationof a force resulting in multi-axial stresses associat
11、ed with anotch, coupled with high rates of loading and in some caseswith high or low temperatures. For some materials andtemperatures the results of impact tests on notched specimens,when correlated with service experience, have been found topredict the likelihood of brittle fracture accurately. Fur
12、therinformation on significance appears in Appendix X1.5. Precautions in Operation of Machine5.1 Safety precautions should be taken to protect personnelfrom the swinging pendulum, flying broken specimens, andhazards associated with specimen warming and cooling media.6. Apparatus6.1 General Requireme
13、nts:6.1.1 The testing machine shall be a pendulum type of rigidconstruction.1These test methods are under the jurisdiction of ASTM Committee E28 onMechanical Testing and are the direct responsibility of Subcommittee E28.07 onImpact Testing.Current edition approved June 1, 2012. Published January 201
14、3. Originallyapproved in 1933. Last previous edition approved 2012 as E23 12. DOI:10.1520/E0023-12A.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 Do
15、cument Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.2 The testing machine shall be designed and built toconform with the requirements given in Annex A1.6.2 Inspection and Verification6.2.1 Inspe
16、ction procedures to verify impact machines di-rectly are provided in A2.2 and A2.3. The items listed in A2.2must be inspected annually.6.2.2 The procedures to verify Charpy V-notch machinesindirectly, using verification specimens, are given in A2.4.Charpy impact machines must be verified directly an
17、d indi-rectly annually.7. Test Specimens7.1 Configuration and Orientation:7.1.1 Specimens shall be taken from the material as speci-fied by the applicable specification.7.1.2 The type of specimen chosen depends largely upon thecharacteristics of the material to be tested. A given specimenmay not be
18、equally satisfactory for soft nonferrous metals andhardened steels; therefore, many types of specimens arerecognized. In general, sharper and deeper notches are requiredto distinguish differences in very ductile materials or whenusing low testing velocities.7.1.3 The specimens shown in Figs. 1 and 2
19、 are those mostwidely used and most generally satisfactory. They are particu-larly suitable for ferrous metals, excepting cast iron.37.1.4 The specimens commonly found suitable for powdermetallurgy materials are shown in Figs. 3 and 4. Powdermetallurgy impact test specimens shall be produced followi
20、ngthe procedure in Practice B925. The impact test results of thesematerials are affected by specimen orientation. Therefore,3Report of Subcommittee XV on Impact Testing of CommitteeA-3 on Cast Iron,Proceedings, ASTM, Vol 33 Part 1, 1933.Perpendicularity between notch axis andspecimen edge62Adjacent
21、(90) sides shall be at 6 10 minCross-section dimensions 6 0.075 mmLength of specimen (L) +0, 2.5 mmCentering of notch (L/2) 6 1mmAngle of notch 61Radius of notch 60.025 mmLigament Length: 60.025 mmType A specimen 60.025 mmType B and C specimen 60.075 mmFinish requirements Ra= 2m on notched surface a
22、nd opposite face;Ra= 4m on other two surfacesFIG. 1 Charpy (Simple-Beam) Impact Test Specimens, Types A, B, and CE23 12a2NOTE 1Permissible variations shall be as follows:Perpendicularity between notch axis andspecimen edge62Cross-section dimensions 60.025 mmLength of specimen +0, 2.5 mmAngle of notc
23、h 61Radius of notch 60.025 mmLigament Length 60.025 mmAdjacent (90) sides shall be at 6 10 minFinish requirements Ra# 2 m on notched surface and opposite face;Ra# 4 m on other two surfacesFIG. 2 Izod (Cantilever-Beam) Impact Test Specimen, Type DDimensionsmmL- Overall Length 55.0 6 1.0W-Width 10.00
24、6 0.13T-Thickness 10.00 6 0.13NOTE 1Adjacent sides shall be at 906 10 min.FIG. 3 Unnotched Charpy (Simple Beam) Impact Test Specimenfor Metal Powder Structural MaterialsDimensionsmmL- Overall Length 75.0 6 1.5W-Width 10.00 6 0.13T-Thickness 10.00 6 0.13NOTE 1Adjacent sides shall be at 906 10 min.FIG
25、. 4 Izod (Cantilever-Beam) Impact Test Specimen for P/MStructural MaterialsE23 12a3unless otherwise specified, the position of the specimen inthe machine shall be such that the pendulum will strike asurface that is parallel to the compacting direction. For powdermetallurgy materials the impact test
26、results are reported asunnotched absorbed impact energy.7.1.5 Sub-size and supplementary specimen recommenda-tions are given in Annex A3.7.2 Specimen Machining:7.2.1 When heat-treated materials are being evaluated, thespecimen shall be finish machined, including notching, afterthe final heat treatme
27、nt, unless it can be demonstrated that theimpact properties of specimens machined before heat treatmentare identical to those machined after heat treatment.7.2.2 Notches shall be smoothly machined but polishing hasproven generally unnecessary. However, since variations innotch dimensions will seriou
28、sly affect the results of the tests,adhering to the tolerances given in Fig. 1 is necessary (Appen-dix X1.2 illustrates the effects from varying notch dimensionson Type A specimens). In keyhole specimens, the round holeshall be carefully drilled with a slow feed rate. The slot may becut by any feasi
29、ble method, but care must be exercised incutting the slot to ensure that the surface of the drilled holeopposite the slot is not damaged.7.2.3 Identification marks shall only be placed in the fol-lowing locations on specimens: either of the 10-mm squareends; the side of the specimen that faces up wh
30、en the specimenis positioned in the anvils (see Note 1); or the side of thespecimen opposite the notch. No markings, on any side of thespecimen, shall be within 10 mm of the center line of the notch.Permanent markers, laser engraving, scribes, electrostatic pen-cils, and other reasonable marking met
31、hods may be used foridentification purposes. However, some marking methods canresult in damage to the specimens if not used correctly. Forexample, excessive heat from electrostatic pencils or deforma-tion to the specimen from stamping can change the mechanicalproperties of the specimen. Therefore, c
32、are must always betaken to avoid damage to the specimen. Stamping and othermarking processes that result in deformation of the specimenshould only be used on the ends of the specimens, prior tonotching.NOTE 1Careful consideration should be given before placing identi-fication marks on the side of th
33、e specimen to be placed up when positionedon the anvils. If the test operator is not careful, the specimen may beplaced in the machine with the identification marking resting on thespecimen supports (that is, facing down). Under these circumstances, theabsorbed energy value obtained may be unreliabl
34、e.8. Procedure8.1 Preparation of the Apparatus:8.1.1 Perform a routine procedure for checking impactmachines at the beginning of each day, each shift, or just priorto testing on a machine used intermittently. It is recommendedthat the results of these routine checks be kept in a log book forthe mach
35、ine. After the testing machine has been ascertained tocomply with Annex A1 and Annex A2, carry out the routinecheck as follows:8.1.1.1 Visually examine the striker and anvils for obviousdamage and wear.8.1.1.2 Check the zero position of the machine by using thefollowing procedure: raise the pendulum
36、 to the latched posi-tion, move the pointer to near the maximum capacity of therange being used, release the pendulum, and read the indicatedvalue. The pointer should indicate zero on machines readingdirectly in energy. On machines reading in degrees, the readingshould correspond to zero on the conv
37、ersion chart furnished bythe machine manufacturer.NOTE 2On machines that do not compensate for windage and frictionlosses, the pointer will not indicate zero. In this case, the indicated values,when converted to energy, shall be corrected for frictional losses that areassumed to be proportional to t
38、he arc of swing.8.1.1.3 The friction and windage loss shall not exceed 0.4 %of scale range being tested and should not change by more than10 % of the percent friction and windage loss measurementspreviously recorded on the machine. If the percent friction andwindage loss does exceed 0.4 % or is sign
39、ificantly differentfrom previous measurements, check the indicating mechanism,the latch height, and the bearings for wear and damage.However, if the machine has not been used recently, let thependulum swing for 50 to 100 cycles, and repeat the percentfriction and windagetest before undertaking repai
40、rs to themachine. To ensure that friction and windage losses are withinallowable tolerances, use one of the following evaluationprocedures:(1) For a machine equipped with an analog scale: raise the pendulum to the latched position; move the pointer to the maximum scale value being used; release the
41、pendulum (without a specimen in the machine); allow the pendulum to cyclefive times (a forward and abackward swing together count as one cycle); prior to the sixth forward swing set the pointer to between 5and 10 % of the maximum scale value being used; after the sixth forward swing record the value
42、 indicated by thepointer (convert to energy if necessary); divide the energy reading by 10; divide by the maximum scale value being used, and multiply by 100 to get the percent friction and windage loss.(2) For machine equipped with a digital display: Determine the percent friction and windage loss
43、per manu-facturers procedure.(3) For machine equipped with both an analog scale anddigital display: Determine the friction and windage loss using the sameindicating device used to report absorbed energy (10.2.3 andA2.4).NOTE 3Prior to 2011 version, the percent friction and windage wasbased on 11 (ha
44、lf) swings and the pointer was not engaged on the firstswing. Now the pointer is engaged on the first swing. The difference is thatthe friction, windage, and pointer losses associated with the first swing areno longer assumed to be zero. On the 1st swing the pointer should go to0.00, so any friction
45、 that will be recorded will only show up on thefollowing 10 (half) swings.8.2 Test Temperature Considerations:8.2.1 The temperature of testing affects the impact proper-ties of most materials. For materials with a body centered cubicstructure, a transition in fracture mode occurs over a tempera-ture
46、 range that depends on the chemical composition andE23 12a4microstructure of the material. Test temperatures may bechosen to characterize material behavior at fixed values, orover a range of temperatures to characterize the transitionregion, lower shelf, or upper shelf behavior, or all of these. The
47、choice of test temperature is the responsibility of the user ofthis test method and will depend on the specific application.For tests performed at room temperature, a temperature of 206 5C is recommended.8.2.2 The temperature of a specimen can change signifi-cantly during the interval it is removed
48、from the temperatureconditioning environment, transferred to the impact machine,and the fracture event is completed (see Note 6). When usinga heating or cooling medium near its boiling point, use datafrom the references in Note 6 or calibration data with thermo-couples to confirm that the specimen i
49、s within the statedtemperature tolerances when the striker contacts the specimen.If excessive adiabatic heating is expected, monitor the speci-men temperature near the notch during fracture.8.2.3 Verify temperature-measuring equipment at least ev-ery six months. If liquid-in-glass thermometers are used, aninitial verification shall be sufficient, however, the device shallbe inspected for problems, such as the separation of liquid, atleast twice annually.8.2.4 Hold the specimen at the desired temperature within 61 C in the temperature condition
