1、Designation: A897/A897M 15A897/A897M 16Standard 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 last rev
2、ision. 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 are subsequently heat treated by an austempering process as defined in10.
3、19.1.1.2 The application of the austempering heat treatment extends the range of properties achievable in ductile iron castings.1.3 No precise quantitative relationship can be stated between the properties of the iron in various locations of the same castingor between the properties of castings and
4、those of a test specimen cast from the same iron (see Appendix X1). However,austempering heat treatment will tend to diminish any differences in mechanical properties.1.4 The production of castings, machining (if required), and the austempering heat treatments may be performed by differentmanufactur
5、ers, as covered in Section 1513. The purchaser should establish by contract agreement, at the time of ordering, theresponsibility of the various parties for meeting the specification requirements.1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard.
6、The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.5.1 ExceptionWithin the text, the SI units are shown in brackets.2. Referenced Documen
7、ts2.1 ASTM Standards:2A247 Test Method for Evaluating the Microstructure of Graphite in Iron CastingsA370 Test Methods and Definitions for Mechanical Testing of Steel ProductsA732/A732M Specification for Castings, Investment, Carbon and Low Alloy Steel for General Application, and Cobalt Alloyfor Hi
8、gh Strength at Elevated TemperaturesA834 Specification for Common Requirements for Iron Castings 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 of Metallic Ma
9、terials2.2 Military Standard:MIL-STD-129 Military Marking for Shipment and Storage33. Ordering Information3.1 Orders for material to this specification shall include the following information:3.1.1 ASTM designation, with year of issue,3.1.2 Grade of austempered ductile iron required (see Table 1 or
10、Table 2 and SectionsSection 6 and 7),3.1.3 Chemical composition requirements, if any (see Section 4),3.1.4 Heat treated microstructure restrictions (see Section 109),3.1.5 Test coupon criteria (see Section 1211),3.1.6 Lot size and tests per lot (see 12.611.6 and Section 1513),1 This specification is
11、 under the jurisdiction of ASTM Committee A04 on Iron Castings and is the direct responsibility of Subcommittee A04.02 on Malleable and DuctileIron Castings.Current edition approved May 1, 2015Aug. 1, 2016. Published May 2015August 2016. Originally approved in 1990. Last previous edition approved in
12、 20112015 asA897/A897M - 06 (2011).A897/A897M 15. DOI: 10.1520/A0897_A0897M-15.10.1520/A0897_A0897M-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards
13、Document Summary page on the ASTM website.3 Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/dodssp.daps.dla.mil.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an
14、indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to
15、be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.7 Special requirements, if desired, including hardness, radiographic soundness, magnetic particle inspection, pressuretightness, dimensions, or su
16、rface finish (see Section 98),3.1.8 Certification, if required (see Section 1614),3.1.9 Special preparation for delivery, if required (see Section 1715).TABLE 1 Mechanical Property Requirements of Grades 1 5Inch-pound units Grade 1130/90/09Grade 2150/110/07Grade 3175/125/04Grade 4200/155/02Grade 523
17、0/185/01Tensile strength, min, ksi 130 150 175 200 230Yield strength, min, ksi 90 110 125 155 185Elongation in 2 in., min, % 9 7 4 2 1Impact energy, ft-lbA 75 60 45 25 15Typical hardness, HBW, kg/mm2B 269341 302375 341444 388477 402512SI units Grade 1900/650/09Grade 21050/750/07Grade 31200/850/04Gra
18、de 41400/1100/02Grade 51600/1300/01Tensile strength, min, MPa 900 1050 1200 1400 1600Yield strength, min, MPa 650 750 850 1100 1300Elongation in 50 mm, min, % 9 7 4 2 1Impact energy, JC 100 80 60 35 20Typical hardness, HBW, kg/mm2D 269341 302375 341444 388477 402512TABLE 1 Mechanical Property Requir
19、ements of Grades 15Inch-pound units Grade 1130/90/09 Grade 2150/110/07 Grade 3175/125/04 Grade 4200/155/02 Grade 5230/185/01Tensile strength, min, ksi 130 150 175 200 230Yield strength, min, ksi 90 110 125 155 185Elongation in 2 in., min, % 9 7 4 2 1Typical hardness, HBW, kg/mm2A 269341 302375 34144
20、4 388477 402512A Unnotched charpy bars tested at 72 7F. The values in the table are a minimum for the average of the highest three test values of the four tested samples. Hardnessis not mandatory and is shown for information only.SI units Grade 1900/650/09 Grade 21050/750/07 Grade 31200/850/04 Grade
21、 41400/1100/02 Grade 51600/1300/01Tensile strength, min, MPa 900 1050 1200 1400 1600Yield strength, min, MPa 650 750 850 1100 1300Elongation in 50 mm, min, % 9 7 4 2 1Typical hardness, HBW, kg/mm2A 269341 302375 341444 388477 402512A Hardness is not mandatory and is shown for information only.C Unno
22、tched charpy bars tested at 22 4C. The values in the table are a minimum for the average of the highest three test values of the four tested samples.D Hardness is not mandatory and is shown for information only.TABLE 2 Mechanical Property Requirements of MixedMicrostructure GradesInch-pound units Gr
23、ade110/70/11Tensile strength, min, ksi 110Yield strength, min, ksi 70Elongation in 2 in., min, % 11Impact energy, ft-lbA 80Typical hardness, HBW, kg/mm2B 241302Typical hardness, HBW, kg/mm2A 241302A Unnotched charpy bars tested at 72 7F.The values in the table are a minimumfor the average of the hig
24、hest three test values of the four tested samples.A Hardness is not mandatory and is shown for information only.SI units Grade750/500/11Tensile Strength, min, MPa 750Yield strength, min, MPa 500Elongation in 50 mm, min, % 11Impact energy, JA 110Typical hardness, HBW, kg/mm2B 241302Typical hardness,
25、HBW, kg/mm2A 241302A Unnotched charpy bars tested at 22 4C.The values in the table are a minimumfor the average of the highest three test values of the four tested samples.A Hardness is not mandatory and is shown for information only.A897/A897M 1624. Chemical Composition4.1 Although this specificati
26、on has no specific chemical requirements, such requirements may be agreed upon between themanufacturer, heat treater, and the purchaser.4.2 Castings that are of sufficient quality (5.1 and Appendix X1) and properly alloyed (have sufficient hardenability) for theaustempering process can be heat treat
27、ed to meet the minimum properties for any of the five grades of ADI listed in Table 1 byproper selection of heat treatment temperatures and times, but may not be properly alloyed to produce castings meeting theminimum properties listed in Table 2. Alloy requirements for the mixed microstructure grad
28、es of ADI (Table 2) will be differentthan those for the five grades of ADI listed in Table 1.5. Microstructure5.1 The graphite component of the microstructure shall consist of a minimum 80 % spheroidal graphite conforming to TypesI and II per Test Method A247.5.2 The matrix microstructure shall subs
29、tantially consist of ausferrite (acicular ferrite and high carbon, stable austenite) forGrades 15 ADI in Table 1. Proeutectoid ferrite will also be present in Grade 110/70/11 750/500/11 in Table 2.5.3 The cooling rate within some sections may not be sufficient to avoid the formation of pearlite or o
30、ther high temperaturetransformation products. In some cases, the maximum acceptable quantities of these microconstituents and the location(s) withinthe casting may be established by agreement between the manufacturer, heat treater, and the purchaser.5.4 Martensite may be present in minor amounts in
31、the microstructures of Grades 200/155/02 1400/1100/02 and 230/185/011600/1300/01. Acceptable quantities of martensite may be established by agreement between the manufacturer, heat treater, andthe purchaser.5.5 The microstructure shall be substantially free of undesirable microconstituents, the deta
32、ils of which shall be agreed uponby the manufacturer, heat treater, and the purchaser.5.6 The manufacturer, heat treater, and the purchaser may agree upon special chemical compositions or processing requirementsto limit the microconstituents described in 5.35.3 5.5, 5.4, and 5.5.6. Mechanical Proper
33、ties6.1 Tensile property requirements include tensile strength, yield strength, and elongation and apply only after austempering heattreatment.6.2 The iron represented by the test specimens shall conform to the requirements as presented in Table 1 or Table 2.6.3 The yield strength shall be determine
34、d by the 0.2 % offset method (see Test Methods E8).7. Impact Requirements7.1 The iron represented by the test specimens shall conform to the impact properties presented in Table 1 or Table 2.7.2 Impact energy requirements apply only after test material has been austempered. The impact test specimens
35、 must be finishground to required dimensions after heat treatment.7. Hardness7.1 The area or areas on the castings where hardness is to be checked shall be established by agreement between themanufacturer and purchaser, or the manufacturer and the end user.7.2 Brinell hardness shall be determined ac
36、cording to Test Method E10 after sufficient material has been removed from thecasting surface to insure representative hardness readings. The 10 mm ball and 3000 kg load shall be used unless otherwisespecified and agreed upon.8. Special Requirements8.1 When specified in the contract or purchase orde
37、r, castings shall meet special requirements as to hardness, chemicalcomposition, microstructure, pressure tightness, radiographic soundness, magnetic particle inspection, dimensions, and surfacefinish. Refer to Specification A834 for a list of common requirements for iron castings not specifically r
38、eferenced elsewhere in thisspecification.8.2 When specified in the contract or purchase order, castings shall meet special requirements prior to the austempering heattreatment operation.9. Heat Treatment9.1 Castings produced in accordance with this specification to achieve the minimum mechanical pro
39、perties in Table 1 shall beheat treated by an austempering process consisting of heating the castings to a fully austenitic, homogeneous condition, coolingA897/A897M 163(at a rate usually sufficient to avoid the formation of pearlite) to a temperature above the martensite start temperature, andisoth
40、ermally transforming the matrix structure for a time sufficient to produce the desired properties. This process shall producea microstructure that is substantially ausferrite.9.2 Castings produced in accordance with this specification to achieve the minimum mechanical properties in Table 2 shall beh
41、eat treated by an austempering process consisting of heating the castings to an intercritical temperature to produce a fullyhomogeneous austenite/ferrite condition, cooling (at a rate usually sufficient to avoid the formation of pearlite) to a temperatureabove the martensite start temperature, and i
42、sothermally transforming the matrix structure for a time sufficient to produce thedesired properties. This process shall produce a microstructure that is substantially a mixture of proeutectoid ferrite and ausferrite.9.3 Upon agreement between the manufacturer and the purchaser, tension test specime
43、ns described in Section 1312 may bemachined prior to the austempering heat treatment. In this case, heat treatment shall be performed in an inert or carbon controlledenvironment so as to prevent carburization, decarburization, or scaling. Handling and fixturing must be such as to prevent test bardis
44、tortion (see X1.4).9.4 Re-austempering of castings or any deviation from the established heat treating process is only permissable with theapproval of the casting purchaser.10. Workmanship, Finish, and Appearance10.1 The surfaces of castings shall be clean and free of adhering molding material, heat
45、 treatment oils or salts, cracks, hot tears,or other injurious defects such as slag and surface porosity. Dimensions shall conform to drawings or patterns supplied by thepurchaser.10.2 Castings shall not have chilled corners or center chill in areas to be machined.10.3 Welding repair is not acceptab
46、le on austempered castings.11. Test Coupons11.1 Separately cast test coupons from which the tension test and Charpy test specimens are machined shall be cast to the sizeand shape shown in Fig. 1 or Fig. 2. A modified keel block cast from the mold shown in Fig. 3 may be substituted for the 1-in.25-mm
47、 Y-block or the 1-in. 25-mm keel block. The test coupons shall be cast in open molds made of suitable core sand havinga minimum wall thickness of 112 in. 38-mm for the 12-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 left in the mold until they have co
48、oled to a black color (900F 480C or less). The size andtype of coupon cast to represent the casting shall be at the option of the purchaser. In case no option is expressed, the manufacturershall make the choice.11.2 When investment castings are made in accordance with this specification, the manufac
49、turer may use cast-to-size testspecimens that are either incorporated in the mold with the castings or separately cast using the same type of mold and the samethermal conditions that are used to produce the castings. The test specimens shall be made to the dimensions shown in Fig. 1 ofFIG. 1 Keel Block for Test CouponsA897/A897M 164Specification A732/A732M or Fig. 5 of Test Methods and Definitions A370. The exact procedure to be used for producing testspecimens shall be agreed upon by the manufacturer and th
