ASTM E292-2009 895 Standard Test Methods for Conducting Time-for-Rupture Notch Tension Tests of Materials.pdf

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1、Designation: E 292 09Standard 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 () 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:2A 453/A 453M Specification for High-Temperature Bolt

5、ingMaterials, with Expansion Coefficients Comparable toAustenitic Stainless SteelsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 8/E 8M Test Methods for Tension Testing of MetallicMaterialsE74 Practice of Calibration of Force-Measuri

6、ng Instru-ments for Verifying the Force Indication of Testing Ma-chinesE 139 Test Methods for Conducting Creep, Creep-Rupture,and Stress-Rupture Tests of Metallic MaterialsE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 220 Test Method for Calibration of Thermocouples ByC

7、omparison TechniquesE 663 Practice for Flame Atomic Absorption Analysis3E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1012 Practice for Verification of Test Frame and Speci-men Alignment Under Tensile and Compressive AxialForce Application2.2 Mili

8、tary Standard:MIL-STD-120 Gage Inspection43. Terminology3.1 DefinitionsThe definitions of terms relating to creeptesting, which appear in Section E of Terminology E6shallapply to the terms used in these test methods. For the purposeof this practice only, some of the more general terms are usedwith t

9、he 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 specimen axis.3.2.2 bending strainthe difference between the strain atthe surface of the specimen and the axial str

10、ain. 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 elongation afterfracture.3.2.4 length of the reduced sectionthe distance betweentangent points of the fillets th

11、at 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.3.2.6 maximum bending strainthe largest value of bend-ing strain in the red

12、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 the1These test methods are

13、 under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.04 onUniaxial Testing.Current edition approved April 1, 2009. Published April 2009. Originallyapproved in 1966. Last previous edition E 292 01.2For referenced ASTM standards, visit

14、 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.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.4Av

15、ailable from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/www.dodssp.daps.mil.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.ends that are gripped. The reduced

16、 section is uniform withintolerances prescribed in Test Methods E 8/E 8M.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 a materi

17、al 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 stress con

18、centrators.5. Apparatus5.1 Testing Machine:5.1.1 The testing machine shall ensure the application of theload 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 c

19、oincidence 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 loading can ari

20、se 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 testing mach

21、ine. Thus, the bending stress ata given load can vary from test to test, and this variation mayresult in a substantial contribution to the scatter in rupturestrength (1, 2).55.1.3 Zero eccentricity cannot be consistently achieved.However, acceptably low values may be consistently achievedby proper d

22、esign, 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 cylindrical speci-mens, precision-machined loading train components employ-ing either bu

23、ttonhead, pin, or threaded grips connected to thetesting machine through precision-machined ball seat loadingyokes 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

24、 used at sufficiently high temperatures and losetheir original capability for providing satisfactory 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 described i

25、n 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 practicalmeans of eva

26、luating 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,it should b

27、e 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 measured at roo

28、mtemperature 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, should acceptanc

29、etests 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 E 1012 or equivalent shall be used forthe measurement and calculation

30、 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 bending stra

31、indue 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 maintained

32、 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 to friction,

33、 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-temperature

34、 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 andmaintain accurate specimen a

35、pplied 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 friction, bellows, or otherload train features.5The numbers in boldface type refer to the list of references at th

36、e end of thisstandard.E2920925.2 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 afterapplication of forc

37、e.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 is particul

38、arly 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 thetest:Up to a

39、nd 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 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 pr

40、ovided 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 at or n

41、ear the notch (either notch for a flat specimen)is required. For a combination of smooth and notched speci-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)

42、or less, a minimum of one additional thermocoupleplaced at the center of the gage is required. For unnotched 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.

43、3.1, additional thermocouples should be added. For speci-mens with unnotched gage sections of 1 in. or less, position theadditional thermocouples at or near the fillets. For specimenswith unnotched gage sections greater than 1 in., position theadditional thermocouples uniformly along the gage sectio

44、n.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 studied t

45、o 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 specifie

46、d in 5.3.1 should not exceed25F (14C) 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 or above th

47、e 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 specime

48、ns 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 severely is thesmall volume at the base of the not

49、ch.6.3 Selection of the exact specimen geometry and themachining practice used to achieve this geometry and 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 various specimens used are geometricallysimilar. Therefore, a comparison of material or different conditions of thesame material on the basis of their notch rupture stren