1、Designation: A842 11aStandard Specification forCompacted Graphite Iron Castings1This standard is issued under the fixed designation A842; 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 parent
2、heses indicates the year of last reapproval. Asuperscript epsilon () 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 (vermiform) shapes and
3、 essentially free of flakegraphite in the bulk of the casting.1.2 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 iron (seeAppendix X1).1.3 The values stated in SI units are to b
4、e regarded asstandard. No other units of measurement are included in thisstandard.1.3.1 ExceptionThe inch-pound units in Figs. 1-3 and 5are standard. SI units are added for information only.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It i
5、s 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 CastingsE8/E
6、8M Test Methods for Tension Testing of MetallicMaterials2.2 Federal Standard:3Federal Standard No. 123 Marking for Shipment (CivilAgencies)2.3 American National Standard:4MIL-STD-129 Marking for Shipment and Storage3. Ordering Information3.1 Orders for material to this specification shall include th
7、efollowing 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 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 designate
8、d by the purchaser, and3.1.6 Special preparation for delivery if required.4. Chemical Composition4.1 It is the intent of this specification to subordinatechemical composition to mechanical properties; however, anychemical requirement may be specified by agreement betweenthe manufacturer and the purc
9、haser.5. Requirements5.1 Compacted graphite cast iron shall be examined metal-lographically for the acceptable graphite formation. Nonde-structive testing such as ultrasonic velocity or resonancefrequency may also be used to determine the graphite nodu-larity. However, in cases of dispute, the metal
10、lographic exami-nation shall prevail.5.2 The metallographic examination shall be performed on asample sectioned from the casting, on a separately cast testcoupon, as shown in Fig. 1, or on a test lug from a casting. Thelocation on the casting from which the metallographic speci-men is sectioned shal
11、l be agreed by the manufacturer and thepurchaser. In the case of a test coupon or test lug, the specimenshall represent the last metal from the treated batch. Thecasting lug dimension and location shall be agreed by manu-facturer and purchaser.5.3 When castings are produced to this specification byt
12、reating 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. When separately cast test coupons areused, the test coupons shall have a chemical compositionrep
13、resentative of that in the castings, produced from that ironpoured, and having a cooling rate equivalent to that obtained1This specification is under the jurisdiction of ASTM Committee A04 on IronCastings and is the direct responsibility of Subcommittee A04.02 on Malleable andDuctile Iron Castings.C
14、urrent edition approved May 1, 2011. Published June 2011. Originallyapproved in 1985. Last previous edition approved in 2011 as A842 - 11. DOI:10.1520/A0842-11A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book o
15、f ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/dodssp.daps.dla.mil.4Available from American National Standards In
16、stitute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.through use of test molds as shown in Figs. 1-3. The size of thecast coupon representing the castings sh
17、all 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.It is the manufacturers required res
18、ponsibility to maintainadequate controls and documentation 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 % minimumTyp
19、e IV graphite (see Plate 1, Graphite Form Types of TestMethod A247). The remainder of the graphite should be TypeI, II, or III, with no free flake graphite (type VII) in the bulk ofthe casting. The presence of up to 20 % of Type I, II, and IIIgraphite gives rise to the definition of a maximum of 20
20、%nodularity in compacted graphite cast iron. The nodularitypercentage can be arrived at by using the manual particlecount, semiautomatic, or automatic image analysis methods.Whichever method is used, the procedure should be agreed onbetween the manufacturer and the purchaser.5.5 Unless otherwise spe
21、cified, the matrix microstructure ofcastings covered by this specification shall be substantially freeof primary cementite.5.6 Flake graphite is not permitted except within the surfacerim zone of the casting. The amount of flake graphite at thesurface shall be agreed by the manufacturer and the purc
22、haser.NOTE 1Flake graphite in the casting surface reduces fatigue life,which should be taken into account during casting design. Machiningremoves this flake graphite and shot blasting generally minimizes itseffect.6. Tensile Requirements6.1 The iron as represented by the test specimens shallconform
23、to the requirements for tensile properties, as identifiedin Table 1.6.2 Tensile properties shall be determined using the test bardescribed in 7.1 or one of the test coupons described in 7.2except as provided in 10.4.6.3 The yield strength presented in Table 1 shall be deter-mined at 0.2 % offset by
24、the offset method as described in TestMethods E8/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. Test bars shall be castto the size and shape as des
25、cribed in Table 2 and shown in Fig.4.7.2 Test coupons shall be separate castings poured from thesame iron as the castings they represent. Test coupons shall beFIG. 1 Test Coupon for Microscopical Examination of Compacted Graphite IronNOTEThe length of the keel block shall be 6 in. (152 mm).Metric Eq
26、uivalentsin. mm in. mm12 12.7 112 38.11 25.4 212 63.5FIG. 2 Keel BlockA842 11a2cast to the size and shape of the Y-block shown in Fig. 5, thekeel block shown in Fig. 2, or the modified keel block shownin Fig. 3.7.3 Test bars and test coupons shall be cast in dried, baked,or chemically bonded molds c
27、onsisting of an aggregate ofsilica sand with the appropriate binders. All molds shall have athickness of sand adjacent to the test piece equal to or greaterthan the thickness of the piece.7.4 Test bars and test coupons shall be subjected to the samethermal treatment as the castings they represent.FI
28、G. 3 Mold for Modified Keel BlockTABLE 1 Tensile RequirementsGradeA250Grade300Grade350Grade400GradeB450Tensile strength, min,MPa250 300 350 400 450Yield 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 requi
29、red mechanicalproperties and microstructure shall be the option of the manufacturer.BThe 450 grade is a pearlitic grade usually produced without heat treatmentwith addition of certain alloys to promote pearlite as a major part of the matrix.FIG. 4 Design and Dimensions for Mold for Separately CastCy
30、lindrical Test BarsTABLE 2 Diameter and Length of Cast Test BarTest Bar NominalAs Cast Diameter, mm Length, mmMinimum Maximum Minimum MaximumB 30 29 31 150 230“Y” Block SizeFor Castingsof ThicknessLess Than12 in. (13 mm)For Castingsof Thickness12 in.(13 mm)to 112 in.(38 mm)For Castingsof Thicknessof
31、 112 in.(38 mm)and OverDimensions in. mm in. mm in. mmA12 13 1 25 3 75B158 40 218 54 5 125C 2 50 3 75 4 100D 4 100 6 150 8 200E 7 175 7 175 7 175approx approx approx approx approx approxFIG. 5 Y-BlockA842 11a38. Tension Test Specimen8.1 The standard round tension test specimen with 50-mmgage length
32、described in Test Methods E8/E8M shall be used.9. Workmanship, Finish, and Appearance9.1 The surface of the casting shall be inspected visually forsurface discontinuities such as cracks, hot tears, adhering sandor scale, cold shuts, and gas holes. Surface discontinuities shallmeet visual acceptance
33、standards mutually agreed on betweenthe purchaser and the supplier.9.2 No repairing by plugging or welding of any kind shallbe permitted unless written permission is granted by thepurchaser.10. Number of Tests and Retests10.1 The manufacturer shall cast a minimum of three testbars for each lot of ca
34、stings intended to conform to thisspecification. The manufacturer shall perform the specifiedtests. If any test specimen shows defective or impropermachining, or obvious lack of continuity of metal, it may bediscarded and replaced by another specimen from another testbar from the same lot. Only one
35、bar needs to be tested if itsresults conform to the property requirements of this specifica-tion.10.2 If after testing, a test specimen shows evidence of adefect, the results of the test may be invalidated and anothertest may be performed on a specimen from the same lot.10.3 If the results of a vali
36、d test fail to conform to therequirements of this specification, two retests shall be made. Ifeither retest fails to meet the specification requirements, thecastings represented by these test specimens shall be rejected.A valid test is one wherein the specimen has been properlyprepared and appears t
37、o be sound and on which the approvedtest procedure has been followed.10.4 If sufficient separately cast test pieces are not available,the manufacturer shall have the option of removing a testspecimen from a location of a representative casting as agreedupon between the manufacturer and purchaser.10.
38、5 If the first test results indicate that a thermal treatmentis needed to meet the test requirements, the entire lot ofcastings and the representative test specimens shall be ther-mally treated together. Testing shall proceed in accordancewith 10.1-10.4.11. Inspection11.1 Unless otherwise specified
39、in the contract or purchaseorder, the manufacturer shall be responsible for carrying out allthe tests and inspections required by this specification, usinghis own or other reliable facilities, and he shall maintaincomplete records of all such tests and inspections. Such recordsshall be available for
40、 review by the purchaser.11.2 The purchaser reserves the right to perform any of theinspections set forth in the specification where such inspectionsare deemed necessary to assure that supplies and servicesconform to the prescribed requirements.12. Certification12.1 When specified in the purchase or
41、der or contract, themanufacturers or suppliers certification shall be furnished tothe purchaser stating that samples representing each lot havebeen manufactured, tested, and inspected in accordance withthis specification and the requirements have been met. Whenspecified in the purchase order or cont
42、ract, a report of the testresults shall be furnished.13. Product Marking13.1 When the size of the casting permits, each casting shallbear the cast date, the identifying mark of the manufacturer,and the part or pattern number at a location shown on thecovering drawing and, if not shown on the drawing
43、, thelocation should be at the discretion of the producer.14. Packaging and Package Marking14.1 Unless otherwise stated in the contract or order, thecleaning, preservation, and packing of castings for shipmentshall be in accordance with the manufacturers commercialpractice. Packaging and marking sha
44、ll also be adequate toidentify the contents and to ensure acceptance and safe deliveryby the carrier for the mode of transportation employed.14.2 U.S. Government ProcurementWhen specified in thecontract or purchase order, marking for shipment shall be inaccordance with the requirements of Federal St
45、andard No. 123for civil agencies and MIL-STD-129 for military activities.SUPPLEMENTARY REQUIREMENTSS1. When specified in the contract or purchase order,castings shall meet special requirements as to hardness, chemi-cal composition, microstructure, pressure tightness, radio-graphic soundness, magneti
46、c particle inspection dimensions,and surface finish.A842 11a4APPENDIX(Nonmandatory Information)X1. MECHANICAL PROPERTIES OF CASTINGSX1.1 The mechanical properties of iron castings are influ-enced by the cooling rate during and after solidification, bychemical composition (particularly carbon equival
47、ent), by thedesign of the casting, by the design and nature of the mold, bygraphite form, by the location and effectiveness of gates andrisers, and by certain other factors. In compacted graphite castiron, the proportions of nodular form and compacted formgraphite can vary in varying sections due to
48、 the above factors.X1.2 The cooling rate in the mold and, therefore, theproperties developed in any particular section are influenced bythe presence of cores, chills, and chaplets; changes in sectionthickness; and the existence of bosses, projections, and inter-sections, such as junctions of ribs an
49、d bosses. Because of thecomplexity of the interactions of these factors, no precisequantitative relationship can be stated between the propertiesof the iron in various locations of the same casting or betweenthe properties of a casting and those of a test specimen castfrom the same iron. When such a relationship is important andmust be known for a specific application, it can be determinedby appropriate experimentation.X1.3 When reliable information is unavailable on therelationship between properties in a casting and those in aseparately cast test specimen, an
