ASTM_E_2948_-_14.pdf

Designation:E294814Standard Test Method forConducting Rotating Bending Fatigue Tests of Solid RoundFine Wire1This standard is issued under the fixed designation E2948;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 is intended as a procedure for theperformance of rotating bending fatigue tests of solid roundfine wire to obtain the fatigue strength of metallic materials ata specified life in the fatigue regime where the strains(stresses)are predominately and nominally linear elastic.This testmethod is limited to the fatigue testing of small diameter solidround wire subjected to a constant amplitude periodic strain(stress).The methodology can be useful in assessing the effectsof internal material structure,such as inclusions,in melttechnique and cold work processing studies.However,there isa caveat.The strain,due to the radial strain gradient imposedby the test methodology,is a maximum at the surface and zeroat the centerline.Thus the test method may not seek out the“weakest link,”largest inclusions,that govern uniaxial highcycle fatigue life where the strain is uniform across the crosssection and where fatigue damage initiates at a subsurfacelocation(1-5).2Also,pre-strain,which can influence fatiguelife,is not included in this test method.NOTE1The following documents,although not specificallymentioned,are considered sufficiently important to be listed in this testmethod:ASTM STP 566 Handbook of Fatigue TestingASTM STP 588 Manual on Statistical Planning and Analysis for FatigueExperimentsASTM STP 731 Tables for Estimating Median Fatigue Limits(6-8)1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.2.Referenced Documents2.1 ASTM Standards:3E468 Practice for Presentation of Constant Amplitude Fa-tigue Test Results for Metallic MaterialsF562 SpecificationforWrought35Cobalt-35Nickel-20Chromium-10Molybdenum Alloy for Surgical ImplantApplications(UNS R30035)E739 Practice for StatisticalAnalysis of Linear or LinearizedStress-Life(S-N)and Strain-Life(-N)Fatigue DataE1823 Terminology Relating to Fatigue and Fracture Testing2.2 ANSI Standard:4ANSI B4.1 Standard Limits and Fits3.Terminology3.1 Definitions:3.1.1 Terms used in this practice shall be as defined inTerminology E1823.4.Summary of Test Method4.1 This test methodology describes a means to characterizethe fatigue response of small diameter solid round wire usinga rotating bending test.Small diameter wire,to be consistentwith Specification F562 definition of“fine wire”,is less than orequal to a diameter of 0.063 in.(1.60 mm).The wire issubjected to a constant-amplitude bending strain(stress)whileit rotates at a fixed speed.This creates a fully reversed,R=minium strain stress!/maximum strain stress!=-1,bending strainat any point on the circumference of the wire.The number ofrevolutions or cycles is counted until a failure(fracture intotwo or more distinct pieces)is detected.Surface effects due toenvironmental factors(for example corrosion or cavitation)canbe extremely important in assessing fatigue performance.Sucheffects can be assessed in a myriad of environments(air,1This test method is under the jurisdiction of ASTM Committee E08 on Fatigueand Fracture and is the direct responsibility of Subcommittee E08.05 on CyclicDeformation and Fatigue Crack Formation.Current edition approved May 1,2014.Published July 2014.DOI:10.1520/E2948-142The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For 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.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 phosphate buffered saline(PBS),NaCl,O2,N2,varyinghumidity,etc.)using the protocol outlined in the standard.5.Significance and Use5.1 A method for obtaining fatigue strain(stress)at aspecific life is of interest to the wire manufacturer,designer andconsumer.The method is useful in production control,materialacceptance and determination of the fatigue strain(stress)ofthe wire at a specific fatigue life,that is,fatigue strength.Rotating bending fatigue testing of small diameter solid roundwire is possible by looping a specimen of predetermined lengththrough an arc of 9