1、Designation: A897/A897M 06 (Reapproved 2011)Standard Specification forAustempered Ductile Iron Castings1This standard is issued under the fixed designation A897/A897M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers ductile iron castings that aresubsequently heat treated by an austempering process asdefined in
3、 10.1.1.2 The application of the austempering heat treatmentextends the range of properties achievable in ductile ironcastings.1.3 No precise quantitative relationship can be stated be-tween the properties of the iron in various locations of the samecasting or between the properties of castings and
4、those of a testspecimen cast from the same iron (see Appendix X1). How-ever, austempering heat treatment will tend to diminish anydifferences in mechanical properties.1.4 The production of castings, machining (if required), andthe austempering heat treatments may be performed by differ-ent manufactu
5、rers, as covered in Section 15. The purchasershould establish by contract agreement, at the time of ordering,the responsibility of the various parties for meeting thespecification requirements.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The
6、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.1.5.1 ExceptionWithin the text, the SI units are shown inbrackets.2. Referenced Documents2.1 A
7、STM Standards:2A247 Test Method for Evaluating the Microstructure ofGraphite in Iron CastingsA370 Test Methods and Definitions for Mechanical Testingof Steel ProductsA732/A732M Specification for Castings, Investment, Car-bon and Low Alloy Steel for General Application, andCobalt Alloy for High Stren
8、gth at Elevated TemperaturesA834 Specification for Common Requirements for IronCastings for General Industrial UseE8 Test Methods for Tension Testing of Metallic MaterialsE10 Test Method for Brinell Hardness of Metallic MaterialsE23 Test Methods for Notched Bar Impact Testing ofMetallic Materials2.2
9、 Military Standard:MIL-STD-129 Military Marking for Shipment and Storage33. Ordering Information3.1 Orders for material to this specification shall include thefollowing information:3.1.1 ASTM designation, with year of issue,3.1.2 Grade of austempered ductile iron required (see Table1 and Sections 6
10、and 7),3.1.3 Chemical composition requirements, if any (see Sec-tion 4),3.1.4 Heat treated microstructure restrictions (see Section10),3.1.5 Test coupon criteria (see Section 12),3.1.6 Lot size and tests per lot (see 12.6 and Section 15),3.1.7 Special requirements, if desired, including hardness,rad
11、iographic soundness, magnetic particle inspection, pressuretightness, dimensions, or surface finish (see Section 9),3.1.8 Certification, if required (see Section 16),3.1.9 Special preparation for delivery, if required (see Sec-tion 17).4. Chemical Composition4.1 Although this specification has no sp
12、ecific chemicalrequirements, such requirements may be agreed upon betweenthe manufacturer, heat treater, and the purchaser.5. Microstructure5.1 The graphite component of the microstructure shallconsist of a minimum 80 % spheroidal graphite conforming toTypes I and II per Test Method A247.1This speci
13、fication 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 Nov. 1, 2011. Published April 2012. Originallyapproved in 1990. Last previous edition approved in 2006 as A8
14、97/A897M - 06.DOI: 10.1520/A0897_A0897M-06R11.2For 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
15、 Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/dodssp.daps.dla.mil.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 The matrix microstructure shall substantia
16、lly consist ofausferrite (acicular ferrite and high carbon, stable austenite).Proeutectoid ferrite will also be present in Grade 110/70/11750/500/11.5.3 The cooling rate within some sections may not besufficient to avoid the formation of pearlite or other hightemperature transformation products. In
17、some cases, the maxi-mum acceptable quantities of these microconstituents and thelocation(s) within the casting may be established by agreementbetween the manufacturer, heat treater, and the purchaser.5.4 Martensite may be present in minor amounts in themicrostructures of Grades 200/155/02 1400/1100
18、/02 and230/185/01 1600/1300/01. Acceptable quantities of marten-site may be established by agreement between the manufac-turer, heat treater, and the purchaser.5.5 The microstructure shall be substantially free of unde-sirable microconstituents, the details of which shall be agreedupon by the manufa
19、cturer, heat treater, and the purchaser.5.6 The manufacturer, heat treater, and the purchaser mayagree upon special chemical compositions or processing re-quirements to limit the microconstituents described in 5.3, 5.4,and 5.5.6. Mechanical Properties6.1 Tensile property requirements include tensile
20、 strength,yield strength, and elongation and apply only after austemper-ing heat treatment.6.2 The iron represented by the test specimens shall con-form to the requirements as presented in Table 1.6.3 The yield strength shall be determined by the 0.2 %offset method (see Test Methods E8).7. Impact Re
21、quirements7.1 The iron represented by the test specimens shall con-form to the impact properties presented in Table 1.7.2 Impact energy requirements apply only after test mate-rial has been austempered. The impact test specimens must befinish ground to required dimensions after heat treatment.8. Har
22、dness8.1 The area or areas on the castings where hardness is to bechecked shall be established by agreement between the manu-facturer and purchaser, or the manufacturer and the end user.8.2 Brinell hardness shall be determined according to TestMethod E10 after sufficient material has been removed fr
23、omthe casting surface to insure representative hardness readings.The 10 mm ball and 3000 kg load shall be used unlessotherwise specified and agreed upon.9. Special Requirements9.1 When specified in the contract or purchase order,castings shall meet special requirements as to hardness, chemi-cal comp
24、osition, microstructure, pressure tightness, radio-graphic soundness, magnetic particle inspection, dimensions,and surface finish. Refer to Specification A834 for a list ofcommon requirements for iron castings not specifically refer-enced elsewhere in this specification.9.2 When specified in the con
25、tract or purchase order,castings shall meet special requirements prior to the austem-pering heat treatment operation.10. Heat Treatment10.1 Castings produced in accordance with this specifica-tion shall be heat treated by an austempering process consistingof heating the castings to a fully austeniti
26、c, homogeneouscondition or an austenite/ferrite condition for Grade 110/70/11750/500/11, cooling (at a rate usually sufficient to avoid theformation of pearlite) to a temperature above the martensitestart temperature, and isothermally transforming the matrixstructure for a time sufficient to produce
27、 the desired properties.This process shall produce a microstructure that is substantiallyausferrite or ausferrite/proeutectoid ferrite for Grade 110/70/11750/500/11.10.2 Upon agreement between the manufacturer and thepurchaser, tension test specimens described in Section 13 maybe machined prior to t
28、he austempering heat treatment. In thiscase, heat treatment shall be performed in an inert or carbonTABLE 1 Mechanical Property Requirements of GradesInch-pound units Grade110/70/11Grade130/90/09Grade150/110/07Grade175/125/04Grade200/155/02Grade230/185/01Tensile strength, min, ksi 110 130 150 175 20
29、0 230Yield strength, min, ksi 70 90 110 125 155 185Elongation in 2 in., min, % 11 9 7 4 2 1Impact energy, ft-lbA80 75 60 45 25 15Typical hardness, HBW, kg/mm2B241302 269341 302375 341444 388477 402512AUnnotched charpy bars tested at 72 6 7F. The values in the table are a minimum for the average of t
30、he highest three test values of the four tested samples.BHardness is not mandatory and is shown for information only.SI units Grade750/500/11Grade900/650/09Grade1050/750/07Grade1200/850/04Grade1400/1100/02Grade1600/1300/01Tensile strength, min, MPa 750 900 1050 1200 1400 1600Yield strength, min, MPa
31、 500 650 750 850 1100 1300Elongation in 50 mm, min, % 11 9 7 4 2 1Impact energy, JA110 100 80 60 35 20Typical hardness, HBW, kg/mm2B241302 269341 302375 341444 388477 402512AUnnotched charpy bars tested at 22 6 4C. The values in the table are a minimum for the average of the highest three test value
32、s of the four tested samples.BHardness is not mandatory and is shown for information only.A897/A897M 06 (2011)2controlled environment so as to prevent carburization, decar-burization, or scaling. Handling and fixturing must be such asto prevent test bar distortion (see X1.4).10.3 Re-austempering of
33、castings or any deviation from theestablished heat treating process is only permissable with theapproval of the casting purchaser.11. Workmanship, Finish, and Appearance11.1 The surfaces of castings shall be clean and free ofadhering molding material, heat treatment oils or salts, cracks,hot tears,
34、or other injurious defects such as slag and surfaceporosity. Dimensions shall conform to drawings or patternssupplied by the purchaser.11.2 Castings shall not have chilled corners or center chill inareas to be machined.11.3 Welding repair is not acceptable on austempered cast-ings.12. Test Coupons12
35、.1 Separately cast test coupons from which the tensiontest and Charpy test specimens are machined shall be cast tothe size and shape shown in Fig. 1 or Fig. 2. A modified keelblock cast from the mold shown in Fig. 3 may be substitutedfor the 1-in. 25-mm Y-block or the 1-in. 25-mm keel block.The test
36、 coupons shall be cast in open molds made of suitablecore sand having a minimum wall thickness of 112 in. 38-mmfor the12-in. 13-mm and 1-in. 25-mm sizes and 3 in.76-mm for the 3-in. 76-mm size. The coupons shall be leftin the mold until they have cooled to a black color (900F480C or less). The size
37、and type of coupon cast to representthe casting shall be at the option of the purchaser. In case nooption is expressed, the manufacturer shall make the choice.12.2 When investment castings are made in accordance withthis specification, the manufacturer may use cast-to-size testspecimens that are eit
38、her incorporated in the mold with thecastings or separately cast using the same type of mold and thesame thermal conditions that are used to produce the castings.The test specimens shall be made to the dimensions shown inFig. 1 of Specification A732/A732M or Fig. 5 of Test Methodsand Definitions A37
39、0. The exact procedure to be used forproducing test specimens shall be agreed upon by the manu-facturer and the purchaser.12.3 When castings made in accordance with this specifi-cation are produced by nodularization directly in the mold, themanufacturer may use either separately cast test coupons or
40、 testspecimens cut from castings. If test bars are to be cut fromcastings, test bar location shall be agreed upon by the purchaserand the manufacturer and indicated on the casting drawing.When separately cast test coupons are used, selection shall beas outlined in 12.1 and shown in Figs. 1-6. Append
41、ix X2provides guidelines for selection of coupons with mold coolingrates representative of various casting sections.12.4 Test coupons shall be poured from the same ladle orheat as the castings they represent and, unless otherwise agreedupon by the manufacturer and the purchaser, shall be subject tot
42、he same post inoculation and alloying practice.12.5 Test coupons shall be heat treated with the castingsthey represent.12.6 The number of test coupons and the number of testsrequired per order or lot size shall be established at the time ofordering. This agreement should include a definition of lot
43、size.Lot size can be defined to include the entire order, a specifiedportion of that order, a specified manufacturing productionperiod, or a specified quantity of parts shipped to the purchaser.12.7 If any test specimen shows obvious defects, anothermay be cut from the same test block or from anothe
44、r test blockrepresenting the same metal. Positions other than “A” or “B” inFig. 4 shall not be used. In those cases where removal of testFIG. 1 Keel Block for Test Coupons“Y” Block SizeDimensionsFor Castings ofThickness LessThan12 in.13 mmFor Castings ofThickness12to 112 in. 13 to 38mmFor Castings o
45、fThickness of 112in. 38 mmand Overin. mm in. mm in. mmA12 13 1 25 3 75B158 40 218 55 5 125C 2 50 3 75 4 100D 4 100 6 150 8 200E 7 175 7 175 7 175approx approx approxF916 14 1116 27 3116 78G718 180 718 180 718 180approx approx approxFIG. 2 Y-Blocks for Test CouponsA897/A897M 06 (2011)3bars from actua
46、l castings has been agreed upon (see 12.2 and12.3), a second test bar may be obtained from an alternatelocation of equivalent section or from a second castingprocessed in the same lot.13. Tension Test Specimens13.1 The standard round tension test specimen with a 2-in.50-mm gage length shown in Fig.
47、5 shall be used, exceptwhen the12-in. 13-mm Y-block coupon is used. In this case,either of the test specimens shown in Fig. 6 shall be satisfac-tory. Tension test specimens shall be machined only fromPositions A (preferred) or B in Fig. 4. The test bars may bemachined before or after heat treatment
48、in accordance with10.2.14. Impact Test Specimens14.1 The unnotched Charpy impact strength shall be deter-mined according to Test Methods E23 with the followingvariations: Specimens are to be prepared unnotched to dimen-sions in Fig. 9 of Test Methods E23. Blanks from which testspecimens are machined
49、 shall be cut only from Positions A orBinFig. 4. Test temperature shall be 72 6 7F 22 6 4C.Four specimens shall be tested, with the lowest impact energyvalue discarded and the remaining three values averaged. Theaverage impact energy shall meet the requirement of Table 1.15. Responsibility for Quality and Inspection15.1 At the time of an order, the purchaser should establishan agreement for quality and inspection requirements with themanufacturers. The form of th
