1、Designation: E23 16a An 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, th
2、e year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 These test methods descri
3、be 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 (see AnnexA2),optional test specimen confi
4、gurations (see Annex A3), desig-nation of test specimen orientation (see Terminology E1823),and determining the percent of shear fracture on the surface ofbroken impact specimens (see Annex A4). In addition, infor-mation is provided on the significance of notched-bar impacttesting (see Appendix X1),
5、 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 other units of measurement are included in thissta
6、ndard.1.3.1 ExceptionSection 8 and Annex A4 provide inch-pound units for information only.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 practic
7、es and determine the applica-bility 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 Pre
8、cision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1823 Terminology Relating to Fatigue and Fracture TestingE2298 Test Method for Instrumented Impact Testing ofMetallic Materials3. Summary of Test Method3.1 The essentia
9、l 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 the specimenplaced in its pat
10、h, 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 associated with anotch, coupled with
11、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. Furtherinformation on significan
12、ce 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 Requirements:6.1.1 The testing machine
13、 shall be a pendulum type of rigidconstruction.6.1.2 The testing machine shall be designed and built toconform with the requirements given in Annex A1.6.2 Inspection and Verification:6.2.1 Inspection procedures to verify impact machines di-rectly are provided in A2.2 and A2.3. The items listed in A2
14、.2must be inspected annually.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 April 1, 2016. Published May 2016. Originallyapproved in 1933. Last previous editi
15、on approved 2016 as E23 16. DOI:10.1520/E0023-16A.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.*A Summary
16、of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.2.2 The procedures to verify Charpy machines indirectly,using verification specimens, are given in A2.4. Charpy impactmachines mus
17、t be verified directly and indirectly 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 g
18、iven specimenmay not be 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 specimen
19、s shown in Figs. 1 and 2 are those mostwidely used and most generally satisfactory. They are particu-larly suitable for ferrous metals, excepting cast iron.3TheCharpy specimen designations are V-notch and U-notch.NOTE 1Keyhole notch specimen is similar to U-notch, except thenotch width is 1.6 mm or
20、less.7.1.4 The specimens commonly found suitable for powdermetallurgy materials are shown in Figs. 3 and 4. Powdermetallurgy impact test specimens shall be produced followingthe procedure in Practices B925. The impact test results ofthese materials are affected by specimen orientation.Therefore,unle
21、ss otherwise specified, the position of the specimen in themachine shall be such that the pendulum will strike a surfacethat is parallel to the compacting direction. For powdermetallurgy materials the impact test results are reported asunnotched absorbed impact energy.7.1.5 Sub-size and supplementar
22、y 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 treatment, unless it can be demonstrated that theimpact properties of specimens machined befor
23、e heat treatmentare identical to those machined after heat treatment.7.2.2 Notches shall be smoothly machined, but polishinghas proven generally unnecessary. However, since variations innotch dimensions will seriously affect the results of the tests,adhering to the tolerances given in Fig. 1 is nece
24、ssary (Appen-dix X1.2 illustrates the effects from varying notch dimensionson V-notch specimens).3Report of Subcommittee XV on Impact Testing of CommitteeA-3 on Cast Iron,Proceedings, ASTM, Vol 33 Part 1, 1933.ID Number Description Dimension Tolerance1 Length of specimen 55 mm +0/-2.5 mm2 Centering
25、of notch 1 mm3 Notch length to edge 90 24 Adjacent sides angle 90 0.175 Width 10 mm 0.075 mm6 Thickness 10 mm 0.075 mm7V Ligament length, Type V 8 mm 0.025 mm7U Ligament length, Type U 5 mm 0.075 mm8V Radius of notch, Type V 0.25 mm 0.025 mm8U Radius of notch, Type U 1 mm 0.025 mm9 Angle of notch 45
26、 1A Surface finish requirements 2 m (Ra) #B Surface finish requirements 4 m (Ra) #FIG. 1 Charpy (Simple-Beam) Impact Test Specimens, V-Notch and U-NotchE23 16a2NOTE 2In keyhole notch specimens, the round hole shall be carefullydrilled with a slow feed rate. The slot may be cut by any feasible method
27、,but care shall be exercised in cutting the slot to ensure that the surface ofthe drilled hole opposite 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 when the sp
28、ecimenis positioned in the anvils (see Note 3); 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, electrostaticpencils, and other reasonable marking methods may be
29、 usedfor identification purposes. However, some marking methodscan result 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, care shall a
30、lways 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 3Careful consideration should be given before placing identi-fication marks on the side of the specimen
31、 to be placed up when positionedID Number Description Dimension Tolerance1 Length of specimen 75 mm +0/-2.5 mm2 Notch to top 28 mm3 Notch length to edge 90 24 Adjacent sides angle 90 0.175 Width 10 mm 0.025 mm6 Thickness 10 mm 0.025 mm7 Ligament length 8 mm 0.025 mm8 Radius of notch 0.25 mm 0.025 mm
32、9 Angle of notch 45 1A Surface finish requirement 2 m (Ra) #B Surface finish requirement 4 m (Ra) #FIG. 2 Izod (Cantilever-Beam) Impact Test SpecimenDimensionsmmL- Overall Length 55.0 1.0W-Width 10.00 0.13T-Thickness 10.00 0.13NOTE 1Adjacent sides shall be at 906 10 min.FIG. 3 Unnotched Charpy (Simp
33、le Beam) Impact Test Specimenfor Metal Powder Structural MaterialsDimensionsmmL- Overall Length 75.0 1.5W-Width 10.00 0.13T-Thickness 10.00 0.13NOTE 1Adjacent sides shall be at 906 10 min.FIG. 4 Izod (Cantilever-Beam) Impact Test Specimen for P/MStructural MaterialsE23 16a3in the anvils. If the test
34、 operator is not careful, the specimen can be placedin the machine with the identification marking resting on the specimensupports (that is, facing down). Under these circumstances, the absorbedenergy value obtained may be unreliable.8. Procedure8.1 Preparation of the Apparatus:8.1.1 Perform a routi
35、ne 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 machine. After the testing machine has been ascertained tocomply with An
36、nex 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 to the latchedposition, move the pointer to near the maximum capaci
37、ty 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 conversion chart furnished bythe machine manufacturer.NOTE 4On machines th
38、at 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 the arc of swing.8.1.1.3 The friction and windage loss shall not exceed
39、 0.4 %of the scale range being tested and should not change by morethan 10 % of the percent friction and windage loss measure-ments previously recorded on the machine. If the percentfriction and windage loss does exceed 0.4 % or is significantlydifferent from previous measurements, check the indicat
40、ingmechanism, the latch height, and the bearings for wear anddamage. However, if the machine has not been used recently,let the pendulum swing for 50 to 100 cycles, and repeat thepercent friction and windage test before undertaking repairs tothe machine. To ensure that friction and windage losses ar
41、ewithin allowable tolerances, use one of the following evalua-tion procedures:(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 pendulum (without a specimen in the machine);Allow the pendulum
42、to cycle five times (a forward and a backwardswing together count as one cycle);Prior to the sixth forward swing set the pointer to between 5 and 10% of the maximum scale value being used;After the sixth forward swing record the value indicated by thepointer (convert to energy if necessary);Divide t
43、he energy reading by 10;Divide by the maximum scale value being used, andMultiply by 100 to get the percent friction and windage loss.(2) A machine equipped with a digital display:Determine the percent friction and windage loss per manufac-turers procedure.(3) For machine equipped with both an analo
44、g scale anddigital display:Determine the friction and windage loss using the sameindicating device used to report absorbed energy (10.2.5 andA2.4).NOTE 5Prior to the 2012 version, the percent friction and windagewas based on 11 (half) swings and the pointer was not engaged on the firstswing. Now the
45、 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 that will be recorded will only show up on thefollowing 10 (half) swi
46、ngs.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 range that depends on the chemical composition andmicrostructure of t
47、he 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. Thechoice of test temperature is the responsibility of the user ofthis test metho
48、d and will depend on the specific application.For tests performed at room temperature, a temperature of20C 6 5C is recommended.8.2.2 The temperature of a specimen can change signifi-cantly during the interval it is removed from the temperatureconditioning environment, transferred to the impact machi
49、ne,and the fracture event is completed (see Note 8). When usinga heating or cooling medium near its boiling point, use datafrom the references in Note 8 or calibration data with thermo-couples to confirm that the specimen is 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,
