1、Designation: E23 16aE23 16b 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 revis
2、ion, the 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
3、 describe notched-bar impact testing of metallic materials by the Charpy (simple-beam) test and the Izod(cantilever-beam) test. They give the requirements for: test specimens, test procedures, test reports, test machines (see Annex A1)verifying Charpy impact machines (see Annex A2), optional test sp
4、ecimen configurations (see Annex A3), designation of testspecimen orientation (see Terminology E1823), and determining the percent of shear fracture on the surface of broken impactspecimens (see Annex A4). In addition, information is provided on the significance of notched-bar impact testing (see Ap
5、pendixX1), and methods of measuring the center of strike (see Appendix X2).1.2 These test methods do not address the problems associated with impact testing at temperatures below 196 C (77 K).1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included
6、 in this standard.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 the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and he
7、alth practices and determine the applicability of regulatorylimitations prior to use. Specific precautionary statements are given in Section 5.2. Referenced Documents2.1 ASTM Standards:2B925 Practices for Production and Preparation of Powder Metallurgy (PM) Test SpecimensE177 Practice for Use of the
8、 Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE1823 Terminology Relating to Fatigue and Fracture TestingE2298 Test Method for Instrumented Impact Testing of Metallic Materials3. Summary of Test Method3.1
9、 The essential features of an impact test are: a suitable specimen (specimens of several different types are recognized), a setof anvils, and specimen supports on which the test specimen is placed to receive the blow of the moving mass, a moving massthat has sufficient energy to break the specimen p
10、laced in its path, and a device for measuring the energy absorbed by the brokenspecimen.4. Significance and Use4.1 These test methods of impact testing relate specifically to the behavior of metal when subjected to a single application ofa force resulting in multi-axial stresses associated with a no
11、tch, coupled with high rates of loading and in some cases with highor low temperatures. For some materials and temperatures the results of impact tests on notched specimens, when correlated withservice experience, have been found to predict the likelihood of brittle fracture accurately. Further info
12、rmation on significanceappears in Appendix X1.1 These test methods are under the jurisdiction of ASTM Committee E28 on Mechanical Testing and are the direct responsibility of Subcommittee E28.07 on ImpactTesting.Current edition approved April 1, 2016June 1, 2016. Published May 2016June 2016. Origina
13、lly approved in 1933. Last previous edition approved 2016 asE23 16.E23 16a. DOI: 10.1520/E0023-16A.10.1520/E0023-16B.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to
14、the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes
15、accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Ha
16、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Precautions in Operation of Machine5.1 Safety precautions should be taken to protect personnel from the swinging pendulum, flying broken specimens, and hazardsassociated with specimen warming and cooling media.6. Apparatus6.
17、1 General Requirements:6.1.1 The testing machine shall be a pendulum type of rigid construction.6.1.2 The testing machine shall be designed and built to conform with the requirements given in Annex A1.6.2 Inspection and Verification:6.2.1 Inspection procedures to verify impact machines directly are
18、provided in A2.2 and A2.3. The items listed in A2.2 mustbe inspected annually.6.2.2 The procedures to verify Charpy machines indirectly, using verification specimens, are given in A2.4. Charpy impactmachines must be verified directly and indirectly annually.7. Test Specimens7.1 Configuration and Ori
19、entation:7.1.1 Specimens shall be taken from the material as specified by the applicable specification.7.1.2 The type of specimen chosen depends largely upon the characteristics of the material to be tested. A given specimen maynot be equally satisfactory for soft nonferrous metals and hardened stee
20、ls; therefore, many types of specimens are recognized. Ingeneral, sharper and deeper notches are required to distinguish differences in very ductile materials or when using low testingvelocities.7.1.3 The specimens shown in Figs. 1 and 2 are those most widely used and most generally satisfactory. Th
21、ey are particularlyID Number Description Dimension Tolerance1 Length of specimen 55 mm +0/-2.5 mm2 Centering 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
22、.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 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 16b2suitable for ferrous metals, ex
23、cepting cast iron.3 The Charpy specimen designations are V-notch and U-notch.NOTE 1Keyhole notch specimen is similar to U-notch, except the notch width is 1.6 mm or less.7.1.4 The specimens commonly found suitable for powder metallurgy materials are shown in Figs. 3 and 4. Powder metallurgyimpact te
24、st specimens shall be produced following the procedure in Practices B925. The impact test results of these materials areaffected by specimen orientation. Therefore, unless otherwise specified, the position of the specimen in the machine shall be suchthat the pendulum will strike a surface that is pa
25、rallel to the compacting direction. For powder metallurgy materials the impact testresults are reported as unnotched absorbed impact energy.7.1.5 Sub-size and supplementary specimen recommendations are given in Annex A3.3 Report of Subcommittee XV on Impact Testing of Committee A-3 on Cast Iron, Pro
26、ceedings, ASTM, Vol 33 Part 1, 1933.ID 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 0.02
27、5 mm9 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 (
28、Simple Beam) Impact Test Specimen for Metal Powder Structural MaterialsE23 16b37.2 Specimen Machining:7.2.1 When heat-treated materials are being evaluated, the specimen shall be finish machined, including notching, after the finalheat treatment, unless it can be demonstrated that the impact propert
29、ies of specimens machined before heat treatment are identicalto those machined after heat treatment.7.2.2 Notches shall be smoothly machined, but polishing has proven generally unnecessary. However, since variations in notchdimensions will seriously affect the results of the tests, adhering to the t
30、olerances given in Fig. 1 is necessary (Appendix X1.2illustrates the effects from varying notch dimensions on V-notch specimens).NOTE 2In keyhole notch specimens, the round hole shall be carefully drilled with a slow feed rate. The slot may be cut by any feasible method, butcare shall be exercised i
31、n cutting the slot to ensure that the surface of the drilled hole opposite the slot is not damaged.7.2.3 Identification marks shall only be placed in the following locations on specimens: either of the 10-mm square ends; theside of the specimen that faces up when the specimen is positioned in the an
32、vils (see Note 3); or the side of the specimen oppositethe notch. No markings, on any side of the specimen, shall be within 10 mm of the center line of the notch. Permanent markers,laser engraving, scribes, electrostatic pencils, and other reasonable marking methods may be used for identification pu
33、rposes.However, some marking methods can result in damage to the specimens if not used correctly. For example, excessive heat fromelectrostatic pencils or deformation to the specimen from stamping can change the mechanical properties of the specimen.Therefore, care shall always be taken to avoid dam
34、age to the specimen. Stamping and other marking processes that result indeformation of the specimen should only be used on the ends of the specimens, prior to notching.NOTE 3Careful consideration should be given before placing identification marks on the side of the specimen to be placed up when pos
35、itioned inthe anvils. If the test operator is not careful, the specimen can be placed in the machine with the identification marking resting on the specimen supports(that is, facing down). Under these circumstances, the absorbed energy value obtained may be unreliable.8. Procedure8.1 Preparation of
36、the Apparatus:8.1.1 Perform a routine procedure for checking impact machines at the beginning of each day, each shift, or just prior to testingon a machine used intermittently. It is recommended that the results of these routine checks be kept in a log book for the machine.After the testing machine
37、has been ascertained to comply with Annex A1 and Annex A2, carry out the routine check as follows:8.1.1.1 Visually examine the striker and anvils for obvious damage and wear.8.1.1.2 Check the zero position of the machine by using the following procedure: raise the pendulum to the latched position,mo
38、ve the pointer to near the maximum capacity of the range being used, release the pendulum, and read the indicated value. Thepointer should indicate zero on machines reading directly in energy. On machines reading in degrees, the reading shouldcorrespond to zero on the conversion chart furnished by t
39、he machine manufacturer.NOTE 4On machines that do not compensate for windage and friction losses, the pointer will not indicate zero. In this case, the indicated values, whenconverted to energy, shall be corrected for frictional losses that are assumed to be proportional to the arc of swing.8.1.1.3
40、The friction and windage loss shall not exceed 0.4 % of the scale range being tested and should not change by morethan 10 % of the percent friction and windage loss measurements previously recorded on the machine. If the percent friction andwindage loss does exceed 0.4 % or is significantly differen
41、t from previous measurements, check the indicating mechanism, theDimensionsmmL- 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/M Structural MaterialsE23 16b4latch height, and the bear
42、ings for wear and damage. However, if the machine has not been used recently, let the pendulum swingfor 50 to 100 cycles, and repeat the percent friction and windage test before undertaking repairs to the machine. To ensure thatfriction and windage losses are within allowable tolerances, use one of
43、the following evaluation 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 to cycle five times (a forward and a backw
44、ardswing 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 the energy reading by 10;Divide by the maxi
45、mum 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 manufacturers procedure.(3) For machine equipped with both an analog scale and digital display:Determine the f
46、riction and windage loss using the same indicating device used to report absorbed energy (10.2.5 and A2.4).NOTE 5Prior to the 2012 version, the percent friction and windage was based on 11 (half) swings and the pointer was not engaged on the first swing.Now the pointer is engaged on the first swing.
47、 The difference is that the friction, windage, and pointer losses associated with the first swing are no longerassumed to be zero. On the 1st swing the pointer should go to 0.00, so any friction that will be recorded will only show up on the following 10 (half)swings.8.2 Test Temperature Considerati
48、ons:8.2.1 The temperature of testing affects the impact properties of most materials. For materials with a body centered cubicstructure, a transition in fracture mode occurs over a temperature range that depends on the chemical composition andmicrostructure of the material. Test temperatures may be
49、chosen to characterize material behavior at fixed values, or over a rangeof temperatures to characterize the transition region, lower shelf, or upper shelf behavior, or all of these. The choice of testtemperature is the responsibility of the user of this test method and will depend on the specific application. For tests performedat room temperature, a temperature of 20C 6 5C is recommended.8.2.2 The temperature of a specimen can change significantly during the interval it is removed from the temperatureconditioning
