1、Designation: E2567 11Standard 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
2、 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
3、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.
4、 A reproducible 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
5、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
6、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 ra
7、nge 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,
8、 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
9、 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 re
10、garded 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 deter
11、mine 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 Defini
12、tionsFor definitions of terms used in this testmethod, see Terminology E7.3.2 Definitions of Terms Specific to This Standard:3.2.1 MFDMaximum Feret Diameter3.2.2 minimum size requirementthe size threshold belowwhich graphite particles are eliminated from the analysis.1This test method is under the j
13、urisdiction of ASTM Committee E04 onMetallography and is the direct responsibility of Subcommittee E04.14 on Quanti-tative Metallography.Current edition approved Jan. 1, 2011. Published February 2011. DOI; 10.1520/E256711.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac
14、t ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.3 nodulea discrete g
15、raphite 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 nodul
16、aritydegree 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
17、 theminimum size requirements, expressed as a percentage. See8.10.3.2.8 percent nodularity by countthe total number ofparticles defined as nodules which meet the minimum sizerequirements divided by the total number of all particles whichmeet the minimum size requirements, expressed as a percent-age.
18、 See 8.10.3.2.9 shape factora number between 0.00 and 1.0 result-ing from formula (Eq 2) of this method.3.2.10 spherulitic graphitein cast iron, a small,spheroidal-shaped crystalline carbon body with a radial growthstructure.4. Summary of Test Method4.1 This test method uses an image analyzer to mea
19、sure thedegree of roundness of graphite particles, viewed on a metal-lographic sectioning plane, that are above a minimum size inorder to determine percent nodularity and nodule density. Themagnification used for the analysis is based on a MaximumFeret Diameter (MFD) $ 50 pixels and # 125 pixels for
20、 theaverage size graphite particle being measured. Particles havinga MFD 300 per mm2, the results vary within 6 10nodules per mm2, while for specimens with nodule counts 100, the agreement has been within 6 10-15 nodules per mm2.11. Keywords11.1 graphite; image analysis; microstructure; nodule count
21、;nodular iron; nodularity; shapeASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof
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24、 views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).E2567 114
