ASTM_E_1304_-_97_2014.pdf

Designation:E130497(Reapproved 2014)Standard Test Method forPlane-Strain(Chevron-Notch)Fracture Toughness ofMetallic Materials1This standard is issued under the fixed designation E1304;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 the determination of plane-strain(chevron-notch)fracture toughnesses,KIvor KIvM,ofmetallic materials.Fracture toughness by this method isrelative to a slowly advancing steady state crack initiated at achevron-shaped notch,and propagating in a chevron-shapedligament(Fig.1).Some metallic materials,when tested by thismethod,exhibit a sporadic crack growth in which the crackfront remains nearly stationary until a critical load is reached.The crack then becomes unstable and suddenly advances athigh speed to the next arrest point.For these materials,this testmethod covers the determination of the plane-strain fracturetoughness,KIvjor KIvM,relative to the crack at the points ofinstability.NOTE1One difference between this test method and Test MethodE399(which measures KIc)is that Test Method E399 centers attention onthe start of crack extension from a fatigue precrack.This test methodmakes use of either a steady state slowly propagating crack,or a crack atthe initiation of a crack jump.Although both methods are based on theprinciples of linear elastic fracture mechanics,this difference,plus otherdifferences in test procedure,may cause the values from this test methodto be larger than KIcvalues in some materials.Therefore,toughness valuesdetermined by this test method cannot be used interchangeably with KIc.1.2 This test method uses either chevron-notched rod speci-mens of circular cross section,or chevron-notched bar speci-mens of square or rectangular cross section(Figs.1-10).Theterms“short rod”and“short bar”are used commonly for thesetypes of chevron-notched specimens.1.3 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.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.2.Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE8/E8M Test Methods for Tension Testing of Metallic Ma-terialsE399 Test Method for Linear-Elastic Plane-Strain FractureToughness KIcof Metallic MaterialsE1823 Terminology Relating to Fatigue and Fracture Testing3.Terminology3.1 Definitions:3.1.1 The terms described in Terminology E1823 are appli-cable to this test method.3.1.2 stress-intensity factor,KIFL3/2the magnitude ofthe mathematically ideal crack-tip stress field(stress-fieldsingularity)for mode I in a homogeneous linear-elastic body.3.1.2.1 DiscussionValues of K for mode I are given by thefollowing equation:KI5 limit y2rx#rx0where:rx=distance from the crack tip to a location where thestress is calculated andy=the principal stress rxnormal to the crack plane.3.2 Definitions of Terms Specific to This Standard:3.2.1 plane-strain(chevron-notch)fracture toughness,KIvor KIvjFL3/2under conditions of crack-tip plane strain in achevron-notched specimen:KIvrelates to extension resistancewith respect to a slowly advancing steady-state crack.KIvjrelates to crack extension resistance with respect to a crackwhich advances sporadically.3.2.1.1 DiscussionFor slow rates of loading the fracturetoughness,KIvor KIvj,is the value of stress-intensity factor as1This test method is under the jurisdiction of ASTM Committee E08 on Fatigueand Fracture and is the direct responsibility of Subcommittee E08.02 on Standardsand Terminology.Current edition approved July 1,2014.Published September 2014.Originallyapproved in 1989.Last previous edition approved in 2009 as E1304 97(2009)1.DOI:10.1520/E1304-97R14.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 measured using the operational procedure(and satisfying all ofthe validity requirements)specified in this test method.3.2.2 plane-strain(chevron-notch)fracture toughness,KIvMFL3/2determined similarly to KIvor KIvj(see 3.2.1)usingthe same specimen,or specimen geometries,but using asimpler analysis based on the maximum test force.Theanalysis is described in Annex A1.Unloading-reloading cyclesas descri