1、Designation: E 292 01Standard Test Methods forConducting Time-for-Rupture Notch Tension Tests ofMaterials1This standard is issued under the fixed designation E 292; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. 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 These test methods cover the determination of the timefor rupture of notched specimens under conditions of constantload and
3、 temperature. These test methods also includes theessential requirements for testing equipment.1.2 The values stated in inch-pound units are to be regardedas the standard. The units in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any
4、, 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-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:A 453/A453M Specification for High-Temperature Bolti
5、ngMaterials, with Expansion Coefficients Comparable toAustenitic Steels2E4 Practices for Force Verification of Testing Machines3E6 Terminology Relating to Methods of Mechanical Test-ing3E8 Test Methods for Tension Testing of Metallic Materials3E74 Practice of Calibration of Force-Measuring Instru-me
6、nts for Verifying the Load Indication of Testing Ma-chines3E 139 Practice for Conducting Creep, Creep-Rupture, andStress-Rupture Tests of Metallic Materials3E 220 Test Method for Calibration of Thermocouples byComparison Techniques4E 633 Guide for Use of Thermocouples in Creep and StressRupture Test
7、ing to 1000C (1800F) in Air3E 1012 Practice for Verification of Specimen AlignmentUnder Tensile Loading32.2 Military Standard:MIL-STD-120 Gage Inspection53. Terminology3.1 DefinitionsThe definitions of terms relating to creeptesting, which appear in Section E of Terminology E6shallapply to the terms
8、 used in these test methods. For the purposeof this practice only, some of the more general terms are usedwith the restricted meanings given below.3.2 Definitions of Terms Specific to This Standard:3.2.1 axial strainthe average of the strain measured onopposite sides and equally distant from the spe
9、cimen axis.3.2.2 bending strainthe difference between the strain atthe surface of the specimen and the axial strain. In general, itvaries from point to point around and along reduced section ofthe specimen.3.2.3 gage lengththe original distance between gagemarks made on the specimen for determining
10、elongation afterfracture.3.2.4 length of the reduced sectionthe distance betweentangent points of the fillets that bound the reduced section.3.2.5 The adjusted length of the reduced section is greaterthan the length of the reduced section by an amount calculatedto compensate for the strain in the fi
11、llets adjacent to thereduced section.3.2.6 maximum bending strainthe largest value of bend-ing strain in the reduced section of the specimen. It can becalculated from measurements of strain at three circumferentialpositions at each of two different longitudinal positions.3.2.7 reduced section of the
12、 specimenthe central portionof the length having a cross section smaller than that of the1These test methods are under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.04 onUniaxial Testing.Current edition approved Oct. 10, 2001. Publis
13、hed December 2001. Originallypublished as E 292 66 T. Last previous edition E 292 83 (Reapproved 1996)e1.2Annual Book of ASTM Standards, Vol 01.01.3Annual Book of ASTM Standards, Vol 03.01.4Annual Book of ASTM Standards, Vol 14.03.5Available from Standardization Documents Order Desk, Bldg. 4, 700 Ro
14、bbinsAve., Philadelphia, PA 19111-5094, Attn: NPODS.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.ends that are gripped. The reduced section is uniform withintolerances prescribed in Test Methods E8.3.2.8 stress-rupture testa test
15、in which time for rupture ismeasured, no deformation measurements being made duringthe test.4. Significance and Use4.1 Rupture life of notched specimens is an indication of theability of a material to deform locally without cracking undermulti-axial stress conditions, thereby redistributing stresses
16、around a stress concentrator.4.2 The notch test is used principally as a qualitative tool incomparing the suitability of materials for designs that willcontain deliberate or accidental stress concentrators.5. Apparatus5.1 Testing Machine:5.1.1 The testing machine shall ensure the application of thel
17、oad to an accuracy of 1 % over the working range.5.1.2 The rupture strength of notched or smooth specimensmay be reduced by bending stresses produced by eccentricityof loading (that is, lack of coincidence between the loadingaxis and the longitudinal specimen axis). The magnitude of theeffect of a g
18、iven amount of eccentricity will increase withdecreasing ductility of the material and, other things beingequal, will be larger for notch than for smooth specimens.Eccentricity of loading can arise from a number of sourcesassociated with misalignments between mating components ofthe loading train in
19、cluding the specimen. The eccentricity willvary depending on how the components of the loading train areassembled with respect to each other and with respect to theattachments to the testing machine. Thus, the bending stress ata given load can vary from test to test, and this variation mayresult in
20、a substantial contribution to the scatter in rupturestrength (1, 2).65.1.3 Zero eccentricity cannot be consistently achieved.However, acceptably low values may be consistently achievedby proper design, machining, and assembly of all componentsof the loading train including the specimen. Devices that
21、 willisolate the loading train from misalignments associated withthe testing machine may also be used. For cylindrical speci-mens, precision-machined loading train components employ-ing either buttonhead, pin, or threaded grips connected to thetesting machine through precision-machined ball seat loa
22、dingyokes have been shown to provide very low bending stresseswhen used with commercial creep testing machines (3). How-ever, it should be emphasized that threaded connections maydeteriorate when used at sufficiently high temperatures and losetheir original capability for providing satisfactory alig
23、nment.5.1.4 Whatever method of gripping is employed, the testingmachine and loading train components when new should becapable of loading a verification specimen at room temperatureas described in 7.2 so that the maximum bending strain is 10 %or less at the lowest anticipated applied force in the cr
24、eep-rupture test. It is recognized that this measurement will notnecessarily represent the performance in the elevated-temperature rupture test, but is designed to provide a practicalmeans of evaluating a given testing machine and its associatedloading train components. Generally, the eccentricity o
25、f load-ing at elevated temperatures will be reduced by the highercompliance, lower modulus of various mating parts as com-pared with the verification test at room temperature. However,it should be recognized that depending on the test conditions,the fits between mating parts may deteriorate with tim
26、e and thatfurnace seals if not properly installed could cause lateral forcesto be applied to the loading rods. In either case, misalignmentsmay be increased relative to the values measured at roomtemperature for new equipment. Axiality requirements andverifications may be omitted when testing perfor
27、med is foracceptance of material to minimum strength requirements. Asdiscussed in 5.1.2, excessive bending would result in reducedstrength or conservative results. In this light, should acceptancetests pass minimum requirements, there would be little benefitto improving axiality of loading. However,
28、 if excessive bend-ing resulted in high rejection rates, economics would probablyfavor improving axiality.5.1.4.1 Test Method E 1012 or equivalent shall be used forthe measurement and calculation of bending strain for cylin-drical or flat specimens.5.1.5 This requirement is intended to limit the max
29、imumcontribution of the testing apparatus to the bending that occursduring a test. It is recognized that even with qualified apparatusdifferent tests may have quite different percent bending straindue to chance orientation of a loosely fitted specimen, lack ofsymmetry of that particular specimen, la
30、teral force fromfurnace packing and thermocouple wire, etc.5.1.6 The testing machine should incorporate means oftaking up the extension of the specimen so that the appliedforce will be maintained within the limits specified in 5.1.1.The extension of the specimen should not allow the loadingsystem to
31、 introduce eccentricity of loading in excess of thelimits specified in 5.1.4. The take-up mechanism should avoidintroducing shock or torque forces to the specimen, andoverloading due to friction, or inertia in the loading system.5.1.7 The testing machine should be erected to securereasonable freedom
32、 from vibration and shock due to externalcauses. Precautions should be made to minimize the transmis-sion of shock to neighboring test machines when a specimenfractures.5.1.8 For high-temperature testing of materials that arereadily attacked by their environment (such as oxidation ofmetal in air), t
33、he sample may be enclosed in a capsule so thatit can be tested in a vacuum or inert gas atmosphere. Whensuch equipment is used, the necessary corrections to obtain andmaintain accurate specimen applied forces must be made. Forinstance, compensation must be made for differences in pres-sures inside a
34、nd outside of the capsule and for any appliedforce variation due to sealing ring friction, bellows, or otherload train features.6The numbers in boldface type refer to the list of references at the end of thisstandard.E2920125.2 Heating Apparatus:5.2.1 The apparatus for and method of heating the spec
35、i-mens should provide the temperature control necessary tosatisfy the requirements specified in 5.3.1 without manualadjustment more frequent than once in each 24-h period afterapplication of force.5.2.2 Heating shall be by an electric resistance or radiationfurnace with the specimen in air at atmosp
36、heric pressure unlessother media are specifically agreed upon in advance.NOTE 1The medium in which the specimens are tested may have aconsiderable effect on the results of tests. This is particularly true when theproperties are influenced by oxidation or corrosion during the test.5.3 Temperature Con
37、trol:5.3.1 Indicated specimen temperature variations along thereduced section and notch(es) on the specimen should notexceed the following limits initially and for the duration of thetest:Up to and including 1800 6 3F (980 6 1.7C)Above 1800 6 5F (980 6 2.8C)5.3.1.1 Guide E 633 or equivalent shall be
38、 used for thethermocouple preparation and use.5.3.2 The temperature should be measured and recorded atleast once each working day. Manual temperature readingsmay be omitted on non-working days provided the periodbetween reading does not exceed 48 h. Automatic recordingcapable of assuring the above t
39、emperature limits at thenotch(es) may be substituted for manual readings provided therecord is read on the next working day.5.3.3 For a notch-only specimen, a minimum of one ther-mocouple at or near the notch (either notch for a flat specimen)is required. For a combination of smooth and notched spec
40、i-mens, in addition to the one thermocouple required at or nearthe notch, one or more thermocouples will be required in theunnotched gage section. If the unnotched gage section is 1 in.(25.4 mm) or less, a minimum of one additional thermocoupleplaced at the center of the gage is required. For unnotc
41、hed gagesections greater than 1 in. (25.4 mm), at least two additionalthermocouples at or near the fillets are required. If thermalgradients are suspected to be greater than the limits given in5.3.1, additional thermocouples should be added. For speci-mens with unnotched gage sections of 1 in. or le
42、ss, position theadditional thermocouples at or near the fillets. For specimenswith unnotched gage sections greater than 1 in., position theadditional thermocouples uniformly along the gage section.5.3.4 The terms “indicated nominal temperature” or “indi-cated temperature” mean the temperature that i
43、s indicated onthe specimen by the temperature-measuring device using goodpyrometric practice.5.3.5 The heating characteristics of the furnace and thetemperature control system should be studied to determine thepower input, voltage fluctuation, temperature set point, propor-tioning control adjustment
44、, reset adjustment, and control ther-mocouple placement necessary to limit transient temperatureovershoot and overheating due to set point error. Overheatingprior to attaining the limits specified in 5.3.1 should not exceed25F (14C) above the indicated nominal test temperature, theduration of such o
45、verheating not to exceed 20 min.5.3.6 In testing materials that are subjected to changes inmechanical properties due to any overheating, and all alloyswhere the test temperature is at or above the temperature offinal heat treatment, overheating should not exceed the limits in5.3.1.6. Test Specimens6
46、.1 The size and shape of test specimens should be basedprimarily on the requirements necessary to obtain representa-tive samples of the material being investigated. If at allpossible, the specimens should be taken from material in theform and condition in which it will be used.6.2 Specimen type, siz
47、e, and shape have a large effect onrupture properties of notch specimens (4, 5, 6, 7). In a notchedspecimen test, the material being tested most severely is thesmall volume at the base of the notch.6.3 Selection of the exact specimen geometry and themachining practice used to achieve this geometry a
48、nd themethods used to measure it should be agreed upon by allparties concerned because of the influence of these factors onrupture life.NOTE 2The notch rupture strength is not only a function of thetheoretical stress concentration, Kt, but also of the absolute size of thespecimen, even though the va
49、rious specimens used are geometricallysimilar. Therefore, a comparison of material or different conditions of thesame material on the basis of their notch rupture strength can only bemade from test results on the same size specimen.6.4 Numerous different specimen geometries have beenused; some cylindrical specimens are suggested in Fig. 1.Asimilar specimen is described in Specification A 453/A 453M.Separate plain and notched specimens may be used instead ofthe combination specimen described in Fig. 1. Suggested flatspecimens are shown in Fig. 2. Notch preparation met
