ASTM_E_2567_-_14.pdf

Designation:E256714Standard Test Method forDetermining Nodularity And Nodule Count In Ductile IronUsing Image Analysis1This standard is issued under the fixed designation E2567;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.INTRODUCTIONDuctile cast iron,also known as nodular cast iron,and spherulitic or spheroidal graphitic iron,isproduced with graphite in a spherulitic form.Nodularizing elements,such as magnesium,cerium,lithium,sodium etc.,are added to a molten metal bath of proper chemical composition to producediscrete particles of spheroidal-shaped graphite.The control of graphite shape is critical to nodulariron properties.Areproducible measurement method is required for evaluation of the cast product andto control process variability.Shape is a difficult parameter to assess using standard chart methods,unless the shape is very close to well-recognized geometric shapes.Nodule density is also difficult toassess by chart methods as nodule size is also a variable and the chart cannot depict nodule densityvariations for nodules of all possible sizes.Stereological and metrological methods provide unbiasedtechniques for assessing structural variations.These procedures are best performed by image analysissystems that eliminate operator subjectivity,bias and inaccuracies associated with manual applicationof stereological and metrological methods.The metallographic sectioning plane will cut through thenodules at random,producing images of graphite nodules with circular or near-circular peripherieswith a range of diameters.1.Scope1.1 This test method is used to determine the percentnodularity and the nodule count per unit area(that is,numberof nodules per mm2)using a light microscopical image ofgraphite in nodular cast iron.Images generated by otherdevices,such as a scanning electron microscope,are notspecifically addressed,but can be utilized if the system iscalibrated in both x and y directions.1.2 Measurement of secondary or temper carbon in othertypes of cast iron,for example,malleable cast iron or ingraphitic tool steels,is not specifically included in this standardbecause of the different graphite shapes and sizes inherent tosuch grades1.3 This standard deals only with the recommended testmethod and nothing in it should be construed as defining orestablishing limits of acceptability or fitness for purpose of thematerial tested.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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:2A247 Test Method for Evaluating the Microstructure ofGraphite in Iron CastingsE3 Guide for Preparation of Metallographic SpecimensE7 Terminology Relating to Metallography3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,see Terminology E7.3.2 Definitions of Terms Specific to This Standard:1This test method is under the jurisdiction of ASTM Committee E04 onMetallography and is the direct responsibility of Subcommittee E04.14 on Quanti-tative Metallography.Current edition approved Dec.1,2014.Published February 2015.Originallyapproved in 2011.Last previous edition approved in 2013 as E256713a.DOI;10.1520/E256714.2For 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 3.2.1 MFDMaximum Feret Diameter3.2.2 minimum size requirementthe size threshold belowwhich graphite particles are eliminated from the analysis.3.2.3 nodulea discrete graphite particle that exceeds boththe required minimum size and shape factor as defined by thismethod.3.2.4 nodule counttotal number of graphite particlesmeeting the definition of a nodule in the area of interest(AOI).3.2.5 nodule density(Nodule count/unit area)number ofnodules per mm2.3.2.6 nodularitydegree of roundness,or closeness to acircular periphery,of a graphite particle in ductile iron basedupon the shape factor.3.2.7 percent nodularity by areathe total area of particlesdefined as nodules which meet the minimum size requirementsdivided by the total area of all particles which meet theminimum size requirements,expressed as a percentage.See8.10.3.2.8 shape factora number between 0.00 and 1.0 result-ing from formula(Eq 2)of this method.3.2.9 spherulitic graphitein c