ASTM_E_1221_-_12a.pdf

Designation:E122112aStandard Test Method forDetermining Plane-Strain Crack-Arrest Fracture Toughness,KIa,of Ferritic Steels1This standard is issued under the fixed designation E1221;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.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 This test method employs a side-grooved,crack-line-wedge-loaded specimen to obtain a rapid run-arrest segment offlat-tensile separation with a nearly straight crack front.Thistest method provides a static analysis determination of thestress intensity factor at a short time after crack arrest.Theestimate is denoted Ka.When certain size requirements aremet,the test result provides an estimate,termed KIa,of theplane-strain crack-arrest toughness of the material.1.2 The specimen size requirements,discussed later,pro-vide for in-plane dimensions large enough to allow the speci-men to be modeled by linear elastic analysis.For conditions ofplane-strain,a minimum specimen thickness is also required.Both requirements depend upon the crack arrest toughness andthe yield strength of the material.A range of specimen sizesmay therefore be needed,as specified in this test method.1.3 If the specimen does not exhibit rapid crack propagationand arrest,Kacannot be determined.1.4 The values stated in SI units are to be regarded as thestandards.The values given in parentheses are provided forinformation only.1.5 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 practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E8 Test Methods for Tension Testing of Metallic MaterialsE23 Test Methods for Notched Bar Impact Testing of Me-tallic MaterialsE208 Test Method for Conducting Drop-Weight Test toDetermine Nil-Ductility Transition Temperature of Fer-ritic SteelsE399 Test Method for Linear-Elastic Plane-Strain FractureToughness KIcof Metallic MaterialsE616 Terminology Relating to Fracture Testing(Discontin-ued 1996)(Withdrawn 1996)3E1304 Test Method for Plane-Strain(Chevron-Notch)Frac-ture Toughness of Metallic MaterialsE1823 Terminology Relating to Fatigue and Fracture Testing3.Terminology3.1 Definitions:3.1.1 Definitions in Terminology E1823 are applicable tothis test method.3.2 Definitions of Terms Specific to This Standard:3.2.1 conditional value of the plane-strain crack-arrestfracture toughness,KQa(FL3/2)the conditional value of KIacalculated from the test results and subject to the validitycriteria specified in this test method.3.2.1.1 DiscussionIn this test method,side-grooved speci-mens are used.The calculation of KQais based upon measure-ments of both the arrested crack size and of the crack-mouthopening displacement prior to initiation of a fast-running crackand shortly after crack arrest.3.2.2 crack-arrest fracture toughness,KA(FL3/2)thevalue of the stress intensity factor shortly after crack arrest asdetermined from dynamic methods of analysis.3.2.2.1 DiscussionThe in-plane specimen dimensionsmust be large enough for adequate enclosure of the crack-tipplastic zone by a linear-elastic stress field.3.2.3 crack-arrest fracture toughness,Ka(FL3/2)thevalue of the stress intensity factor shortly after crack arrest,asdetermined from static methods of analysis.3.2.3.1 DiscussionThe in-plane specimen dimensionsmust be large enough for adequate enclosure of the crack-tipplastic zone by a linear-elastic stress field.1This test method is under the jurisdiction of ASTM Committee E08 on Fatigueand Fracture and is the direct responsibility of Subcommittee E08.07 on FractureMechanics.Current edition approved Nov.1,2012.Published May 2013.Originallyapproved in 1988.Last previous edition approved in 2012 as E1221 12.DOI:10.1520/E1221-12A.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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2.4 plane-strain crack-arrest fracture toughness,KIa(FL3/2)the value of crack-arrest fracture toughness,Ka,fora crack that arrests under conditions of crack-front plane-strain.3.2.4.1 DiscussionThe requirements for attaining condi-tions of crack-front plane-strain are specified in the proceduresof this test method.3.2.5 stress intensity factor at crack initiation,Ko(FL3/2)the value of K at the onset of rapid fracturing.3.2.5.1 DiscussionIn this test method,only a nominalestimate of the initial driv