ASTM A842-1985(2004) Standard Specification for Compacted Graphite Iron Castings《高密度石墨铸铁的标准规范》.pdf
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1、Designation: A 842 85 (Reapproved 2004)Standard Specification forCompacted Graphite Iron Castings1This standard is issued under the fixed designation A 842; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers castings made of compactedgraphite iron, which is described as cast iron with the graphitein compacted (v
3、ermiform) shapes and essentially free of flakegraphite.1.2 The values stated in SI units are to be considered as thestandard.1.3 No precise quantitative relationship can be stated be-tween the properties of iron in the various locations of the samecasting and those of a test bar cast from the same i
4、ron (seeAppendix X1).2. Referenced Documents2.1 ASTM Standards:2A 247 Test Method for Evaluating the Microstructure ofGraphite in Iron CastingsE8M Test Methods for Tension Testing of Metallic Mate-rials (Metric)2.2 Federal Standard:3Fed. Std. No. 123 Marking for Shipment (Civil Agencies)2.3 American
5、 National Standard:4MIL-STD-129 Marking for Shipment and Storage3. Ordering Information3.1 Orders for material to this specification shall include thefollowing information:3.1.1 ASTM designation and year of issue,3.1.2 Grade of compacted graphite iron required as identi-fied in Table 1,3.1.3 Special
6、 properties if required, (see 4.1 and 10.1),3.1.4 If samples other than those identified in Section 9 arerequired,3.1.5 Certification if so designated by the purchaser, and3.1.6 Special preparation for delivery if required.4. Chemical Composition4.1 It is the intent of this specification to subordin
7、atechemical composition to mechanical properties; however, anychemical requirement may be specified by agreement betweenthe manufacturer and the purchaser.5. Microstructure Requirements Microstructure Requirements5.1 Compacted graphite cast iron shall be examined metal-lographically for the acceptab
8、le graphite formation.5.2 The metallographic examination shall be performed on acasting, a separately cast test coupon, as shown in Fig. 1 or ona test lug from a casting. The test coupon or casting lug shallrepresent the last metal from the treated batch. The casting lugdimension and location will b
9、e agreed on by manufacturer andpurchaser.5.3 When castings are produced to this specification bytreating the iron in the mold for graphite form control, themanufacturer may use separately cast test coupons or cut testspecimens from castings to qualify conformance of the micro-structure requirements.
10、 When separately cast test coupons areused, the test coupons shall have a chemical compositionrepresentative of that in the castings, produced from that ironpoured, and having a cooling rate equivalent to that obtainedthrough use of test molds as shown in Figs. 1-4. The size of thecast coupon repres
11、enting the castings shall be the option of thepurchaser. In case no option is expressed, the manufacturershall make the choice. When test specimens are to be takenfrom a casting, the location shall be agreed on by the purchaserand the manufacturer and documented on the casting drawing.1This specific
12、ation is under the jurisdiction of ASTM Committee A04 on IronCastings and is the direct responsibility of Subcommittee A04.02 on Malleable andDuctile Iron Castings.Current edition approved May 1, 2004. Published May 2004. Originallyapproved in 1985. Last previous edition approved in 1997 as A 842 -
13、85 (1997).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.3Available from Standardization Documents Order Des
14、k, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.TABLE 1 Tensile RequirementsGradeA250Grade300Grade350Grade400GradeB450Tensile strength, min,MPa250 300 350 400 45
15、0Yield strength, min,MPa175 210 245 280 315Elongation in 50 mm,min, %3.0 1.5 1.0 1.0 1.0AThe 250 grade is a ferritic grade. Heat treatment to attain required mechanicalproperties and microstructure shall be the option of the manufacturer.BThe 450 grade is a pearlitic grade usually produced without h
16、eat treatmentwith addition of certain alloys to promote pearlite as a major part of the matrix.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.It is the manufacturers required responsibility to maintainadequate controls and documenta
17、tion to assure the customerthat test specimen microstructures are representative of micro-structure in the castings shipped.5.4 The acceptable graphite formation in the microstructureof the test coupon or casting lug shall contain 80 % minimumType IV graphite (see Plate 1, Graphite Form Types of Tes
18、tMethod A 247). The percentage graphite can be arrived at byusing the manual particle count, semiautomatic, or automaticimage analysis methods. Whichever method is used, theprocedure should be agreed on between the manufacturer andthe purchaser.5.5 Unless otherwise specified, the matrix microstructu
19、re ofcastings covered by this specification shall be substantially freeof primary cementite.6. Tensile Requirements6.1 The iron as represented by the test specimens shallconform to the requirements for tensile properties, as identifiedin Table 1.6.2 The yield strength presented in Table 1 shall be d
20、eter-mined at 0.2 % offset by the offset method as described in TestMethods E8M. Other methods may be used by mutualagreement between manufacturer and purchaser.7. Cast Test Bars7.1 Test bars shall be separate castings poured from thesame iron as the castings they represent. The 30-mm diametercylind
21、rical test bar shall be used as described in Table 2 andshown in Fig. 2.7.2 Test coupons may also be cast to the size and shape ofthe keel block or modified keel block shown in Fig. 3 and Fig.4, respectively.7.3 Test bars and test coupons shall be cast in dried, baked,or chemically bonded molds cons
22、isting of an aggregate ofsilica sand with the appropriate binders. All molds shall have aFIG. 1 Test Coupon for Microscopical Examination of Compacted Graphite IronFIG. 2 Design and Dimensions for Mold for Separately CastCylindrical Test BarsNOTEThe length of the keel block shall be 6 in. (152 mm).M
23、etric Equivalentsin. mm in. mm12 12.7 112 38.11 25.4 212 63.5FIG. 3 Keel BlockA 842 85 (2004)2thickness of sand adjacent to the test piece equal to or greaterthan the thickness of the piece.7.4 The test bars or test coupons shall be poured from thesame ladle or heat of iron as the castings they repr
24、esent.7.5 Test bars and test coupons shall be subjected to the samethermal treatment as the castings they represent.8. Tension Test Specimen8.1 The standard round tension test specimen with 50-mmgage length described in Test Methods E8Mshall be used.9. Workmanship, Finish, and Appearance9.1 The surf
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