ASTM_B_646_-_17.pdf

Designation:B64617Standard Practice forFracture Toughness Testing of Aluminum Alloys1This standard is issued under the fixed designation B646;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1 Fracture toughness is a key property for a number ofaluminum alloys utilized in aerospace and process industries.Fracture toughness testing is often required for supplierqualification,quality control,and material release purposes.The purpose of this practice is to provide uniform testprocedures for the industry,pointing out which current stan-dards are utilized in specific cases,and providing guidelineswhere no standards exist.This practice provides guidance fortesting(a)sheet and other products having a specified thick-ness less than 6.35 mm(0.250 in.),(b)intermediate thicknessesof plate,forgings,and extrusions that are too thin for validplane-strain fracture toughness testing but too thick for treat-ment as sheet,such as products having a specified thicknessgreater than or equal to 6.35 mm(0.250 in.)but less than 25 to50 mm(1 to 2 in.),depending on toughness level,and(c)relatively thick products where Test Method E399 is appli-cable.1.2 This practice addresses both direct measurements offracture toughness and screening tests,the latter recognizingthe complexity and expense of making formal fracture tough-ness measurements on great quantities of production lots.1.3 The values stated in SI units are to be regarded as thestandard.The values in inch-pound units given in parenthesisare provided for information purposes only.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.1.5 This international standard was developed in accor-dance with internationally 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:2B557 Test Methods for Tension Testing Wrought and CastAluminum-and Magnesium-Alloy ProductsB557M Test Methods for Tension Testing Wrought and CastAluminum-and Magnesium-Alloy Products(Metric)B645 Practice for Linear-Elastic PlaneStrain FractureToughness Testing of Aluminum AlloysE399 Test Method for Linear-Elastic Plane-Strain FractureToughness KIcof Metallic MaterialsE561 Test Method forKRCurve DeterminationE1304 Test Method for Plane-Strain(Chevron-Notch)Frac-ture Toughness of Metallic MaterialsE1823 Terminology Relating to Fatigue and Fracture Testing3.Terminology3.1 The terminology and definitions in the referenceddocuments,especially E1823,are applicable to this practice.3.2 Definitions of Terms Specific to This Standard:3.2.1 For purposes of this practice,the following descrip-tions of terms are applicable in conjunction with Test MethodE561:3.2.2 CMODcrack mouth opening displacement;the mea-surement of specimen displacement between two points span-ning the machined notch at locations specific to the specimenbeing tested.3.2.3 KR25a value of KRon the KRcurve based on a 25%secant intercept of the force-CMOD test record from a C(T)specimen and the effective crack size aeat that point thatotherwise satisfies the remaining-ligament criterion of TestMethod E561.If the maximum force is reached prior to the25%secant intercept point,the maximum force point shall beused instead to determine the KR25value.1This practice is under the jurisdiction of ASTM Committee B07 on LightMetals and Alloys and is the direct responsibility of Subcommittee B07.05 onTesting.Current edition approved Aug.1,2017.Published August 2017.Originallyapproved in 1978.Last previous edition approved in 2012 as B646 12.DOI:10.1520/B0646-17.2For 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.*A Summary of Changes section appears at the end of this standardCopyright 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 principles 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.1 3.2.4 Kcfor the purpos