ASTM E292-2018 2440 Standard Test Methods for Conducting Time-for-Rupture Notch Tension Tests of Materials《材料断裂时间缺口拉伸试验的标准试验方法》.pdf

1、Designation: E292 18Standard Test Methods forConducting Time-for-Rupture Notch Tension Tests ofMaterials1This standard is issued under the fixed designation E292; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev

2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 constantforce and t

3、emperature. 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationall

5、y recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A453/A453M Spe

6、cification for High-Temperature Bolting,with Expansion Coefficients Comparable to AusteniticStainless SteelsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE8/E8M Test Methods for Tension Testing of Metallic Ma-terialsE74 Practices for C

7、alibration and Verification for Force-Measuring InstrumentsE139 Test Methods for Conducting Creep, Creep-Rupture,and Stress-Rupture Tests of Metallic MaterialsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE220 Test Method for Calibration of Thermocouples ByComparison Techn

8、iquesE633 Guide for Use of Thermocouples in Creep and Stress-Rupture Testing to 1800F (1000C) in AirE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1012 Practice for Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive A

9、xialForce Application2.2 Military Standard:MIL-STD-120 Gage Inspection33. Terminology3.1 DefinitionsThe definitions of terms relating to creeptesting, that appears in Terminology E6 shall apply to the termsused in these test methods. For the purpose of this practiceonly, some of the more general ter

10、ms are used with therestricted 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 specimen axis.3.2.2 bending strainthe difference between the strain atthe surface of the specimen

11、and the axial strain. In general, itvaries from point to point around and along reduced section ofthe specimen.3.2.3 gauge lengththe original distance between gaugemarks made on the specimen for determining elongation afterfracture.3.2.4 length of the reduced sectionthe distance betweentangent point

12、s 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 fillets adjacent to thereduced section.1These test methods are under the jurisdiction of ASTM C

13、ommittee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.04 onUniaxial Testing.Current edition approved April 1, 2018. Published May 2018. Originallyapproved in 1966. Last previous edition approved in 2009 as E292 091which waswithdrawn February 2018 and reinstated in Ap

14、ril 2018. DOI: 10.1520/E0292-18.2For 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.3Available from DLA Document

15、Services, Building 4/D, 700 Robbins Ave.,Philadelphia, PA 19111-5094, http:/quicksearch.dla.mil.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized pri

16、nciples on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.6 maximum bending strainthe largest value of bendingstrain in the red

17、uced 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 specimenthe central portionof the length having a cross section smaller than that of theends that are gripped.

18、The reduced section is uniform withintolerances prescribed in Test Methods E8/E8M.3.2.8 stress-rupture testa test 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

19、 a material to deform locally without cracking undermulti-axial stress conditions, thereby redistributing stressesaround 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 s

20、tress concentrators.5. Apparatus5.1 Testing Machine:5.1.1 The testing machine shall ensure the application of theforce 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,

21、 lack of coincidence between the loadingaxis and the longitudinal specimen axis). The magnitude of theeffect of a given 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 loadi

22、ng can arise from a number of sourcesassociated with misalignments between mating components ofthe loading train including 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 te

23、sting machine. Thus, the bending stress ata given force can vary from test to test, and this variation mayresult in a substantial contribution to the scatter in rupturestrength (1, 2).45.1.3 Zero eccentricity cannot be consistently achieved.However, acceptably low values may be consistently achieved

24、by proper design, machining, and assembly of all componentsof the loading train including the specimen. Devices that willisolate the loading train from misalignments associated withthe testing machine may also be used. For cylindricalspecimens, precision-machined loading train components em-ploying

25、either buttonhead, pin, or threaded grips connected tothe testing machine through precision-machined ball seatloading yokes have been shown to provide very low bendingstresses when used with commercial creep testing machines(3). However, it should be emphasized that threaded connec-tions may deterio

26、rate when used at sufficiently high tempera-tures and lose their original capability for providing satisfac-tory alignment.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

27、 described in 7.2 so that the maximum bending strain is 10 %or less at the lowest anticipated applied force in the creep-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 practical

28、means of evaluating a given testing machine and its associatedloading train components. Generally, the eccentricity of 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

29、,it should be recognized that depending on the test conditions,the fits between mating parts may deteriorate with time 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 mea

30、sured at roomtemperature for new equipment. Axiality requirements andverifications may be omitted when testing performed 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, shou

31、ld acceptancetests pass minimum requirements, there would be little benefitto improving axiality of loading. However, if excessive bend-ing resulted in high rejection rates, economics would probablyfavor improving axiality.5.1.4.1 Test Method E1012 or equivalent shall be used forthe measurement and

32、calculation of bending strain for cylin-drical or flat specimens.5.1.5 This requirement is intended to limit the maximumcontribution 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 b

33、ending straindue to chance orientation of a loosely fitted specimen, lack ofsymmetry of that particular specimen, lateral 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

34、 maintained within the limits specified in 5.1.1.The extension of the specimen should not allow the loadingsystem to 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 t

35、o friction, or inertia in the loading system.5.1.7 The testing machine should be erected to securereasonable freedom 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-

36、temperature testing of materials that arereadily attacked by their environment (such as oxidation ofmetal in air), the 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 and4The numbers in b

37、oldface type refer to the list of references at the end of thisstandard.E292 182maintain accurate specimen applied forces must be made. Forinstance, compensation must be made for differences in pres-sures inside and outside of the capsule and for any appliedforce variation due to sealing ring fricti

38、on, bellows, or otherload train features.5.2 Heating Apparatus:5.2.1 The apparatus for and method of heating the speci-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 afterapplica

39、tion of force.5.2.2 Heating shall be by an electric resistance or radiationfurnace with the specimen in air at atmospheric 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

40、 is particularly true when theproperties are influenced by oxidation or corrosion during the test.5.3 Temperature Control: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 the

41、test:Up to and including 1800 3 F (980 1.7 C)Above 1800 5 F (980 2.8 C)5.3.1.1 Guide E633 or equivalent shall be 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

42、days provided the periodbetween reading does not exceed 48 h. Automatic recordingcapable of assuring the above temperature 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

43、at or near the notch (either notch for a flat specimen)is required. For a combination of smooth and notchedspecimens, in addition to the one thermocouple required at ornear the notch, one or more thermocouples will be required inthe unnotched gauge section. If the unnotched gauge section is1 in. (25

44、.4 mm) or less, a minimum of one additionalthermocouple placed at the center of the gauge is required. Forunnotched gauge sections greater than 1 in. (25.4 mm), at leasttwo additional thermocouples at or near the fillets are required.If thermal gradients are suspected to be greater than the limitsgi

45、ven in 5.3.1, additional thermocouples should be added. Forspecimens with unnotched gauge sections of 1 in. or less,position the additional thermocouples at or near the fillets. Forspecimens with unnotched gauge sections greater than 1 in.,position the additional thermocouples uniformly along thegau

46、ge section.5.3.4 The terms “indicated nominal temperature” or “indi-cated temperature” mean the temperature that is 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

47、studied to determine thepower input, voltage fluctuation, temperature set point, propor-tioning control adjustment, reset adjustment, and control ther-mocouple placement necessary to limit transient temperatureovershoot and overheating due to set point error. Overheatingprior to attaining the limits

48、 specified in 5.3.1 should not exceed25 F (14 C) above the indicated nominal test temperature, theduration of such overheating 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

49、or above the temperature offinal heat treatment, overheating should not exceed the limits in5.3.1.6. Test Specimens6.1 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, size, and shape have a large effect onrupture properties of notch specimens (4, 5, 6, 7). In a notchedspecimen test, the material being tested most s