ASTM_E_1820_-_15a.pdf

Designation:E182015aStandard Test Method forMeasurement of Fracture Toughness1This standard is issued under the fixed designation E1820;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 covers procedures and guidelines forthe determination of fracture toughness of metallic materialsusing the following parameters:K,J,and CTOD().Tough-ness can be measured in the R-curve format or as a point value.The fracture toughness determined in accordance with this testmethod is for the opening mode(Mode I)of loading.NOTE1Until this version,KIccould be evaluated using this testmethod as well as by using Test Method E399.To avoid duplication,theevaluation of KIchas been removed from this test method and the user isreferred to Test Method E399.1.2 The recommended specimens are single-edge bend,SE(B),compact,C(T),and disk-shaped compact,DC(T).All specimens contain notches that are sharpened with fatiguecracks.1.2.1 Specimen dimensional(size)requirements vary ac-cording to the fracture toughness analysis applied.The guide-lines are established through consideration of materialtoughness,material flow strength,and the individual qualifi-cation requirements of the toughness value per values sought.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 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.NOTE2Other standard methods for the determination of fracturetoughness using the parameters K,J,and CTOD are contained in TestMethods E399,E1290,and E1921.This test method was developed toprovide a common method for determining all applicable toughnessparameters from a single test.2.Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE8/E8M Test Methods for Tension Testing of Metallic Ma-terialsE21 Test Methods for Elevated Temperature Tension Tests ofMetallic MaterialsE23 Test Methods for Notched Bar Impact Testing of Me-tallic MaterialsE399 Test Method for Linear-Elastic Plane-Strain FractureToughness KIcof Metallic MaterialsE1290 Test Method for Crack-Tip Opening Displacement(CTOD)Fracture Toughness Measurement(Withdrawn2013)3E1823 Terminology Relating to Fatigue and Fracture TestingE1921 Test Method for Determination of ReferenceTemperature,To,for Ferritic Steels in the TransitionRangeE1942 Guide for Evaluating Data Acquisition Systems Usedin Cyclic Fatigue and Fracture Mechanics TestingE2298 Test Method for Instrumented Impact Testing ofMetallic Materials3.Terminology3.1 Terminology E1823 is applicable to this test method.Only items that are exclusive to Test Method E1820,or thathave specific discussion items associated,are listed in thissection.3.2 Definitions of Terms Specific to This Standard:3.2.1 compliance LF1,nthe ratio of displacement in-crement to force increment.3.2.2 crack opening displacement(COD)L,nforce-induced separation vector between two points at a specific gagelength.The direction of the vector is normal to the crack plane.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 Oct.15,2015.Published November 2015.Originallyapproved in 1996.Last previous edition approved in 2015 as E1820 15.DOI:10.1520/E1820-15A2For 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 3.2.2.1 DiscussionIn this practice,displacement,v,is thetotal displacement measured by clip gages or other devicesspanning the crack faces.3.2.3 crack extension,a L,nan increase in crack size.3.2.4 crack-extension force,G FL1or FLL2,ntheelastic energy per unit of new separation area that is madeavailable at the front of an ideal crack in an elastic solid duringa virtual increment of forward crack extension.3.2.5 crack-tip opening displacement(CTOD),L,ncrack displacement resulting from the total deformation(elastic plus plastic)at variously defined locations near theoriginal(prior to force application)crack tip.3.2.5.1 DiscussionIn this test method,CTOD is the dis-placement of the crack surfaces normal to the original(un-loaded)crack plane at the t