ASTM A897/A897M-22

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it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: A897/A897M − 16 A897/A897M − 22
Standard Specification for
Austempered Ductile Iron Castings
This standard is issued under the fixed designation A897/A897M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last 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. Scope
1.1 This specification covers ductile iron castings that are subsequently heat treated by an austempering process as defined in 9.1.
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 casting
or between the properties of castings and 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 different
manufacturers, as covered in Section 13. The purchaser should establish by contract agreement, at the time of ordering, the
responsibility 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. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformancenonconformance with the standard.
1.5.1 Exception—Within the text, the SI units are shown in brackets.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
A247 Test Method for Evaluating the Microstructure of Graphite in Iron Castings
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A732/A732M Specification for Castings, Investment, Carbon and Low-Alloy Steel for General Application, and Cobalt Alloy
for High Strength at Elevated Temperatures
A834 Specification for Common Requirements for Iron Castings for General Industrial Use
E8E8/E8M Test Methods for Tension Testing of Metallic Materials [Metric] E0008_E0008M
This specification is under the jurisdiction of ASTM Committee A04 on Iron Castings and is the direct responsibility of Subcommittee A04.02 on Malleable and Ductile
Iron Castings.
Current edition approved Aug. 1, 2016Oct. 1, 2022. Published August 2016October 2022. Originally approved in 1990. Last previous edition approved in 20152016 as
A897/A897M – 15.A897/A897M – 16. DOI: 10.1520/A0897_A0897M-16.10.1520/A0897_A0897M-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A897/A897M − 22
E10 Test Method for Brinell Hardness of Metallic Materials
E23 Test Methods for Notched Bar Impact Testing of Metallic Materials
2.2 Military Standard:
MIL-STD-129 Military Marking for Shipment and Storage
3. Ordering Information
3.1 Orders for material to this specification shall include the following information:
3.1.1 ASTM designation, with year of issue,issue.
3.1.2 Grade of austempered ductile iron required (see Table 1 or Table 2 and Section 6),).
3.1.3 Chemical composition requirements, if any (see Section 4),).
3.1.4 Deviations to tensile strength and elongation with increasing section thickness (see 6.4).
3.1.5 Heat treated Heat-treated microstructure restrictions (see Section 9),).
3.1.6 Test coupon criteria (see Section 11),).
3.1.7 Lot size and tests per lot (see 11.6 and Section 13),).
3.1.8 Special requirements, if desired, including hardness, radiographic soundness, magnetic particle inspection, pressure
tightness, dimensions, or surface finish (see Section 8),).
3.1.9 Certification, if required (see Section 14),).
3.1.10 Special preparation for delivery, if required (see Section 15).
4. Chemical Composition
4.1 Although this specification has no specific chemical requirements, such requirements may be agreed upon between the
manufacturer, 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 the
austempering process can be heat treated to meet the minimum properties for any of the five grades of ADI listed in Table 1 by
proper selection of heat treatment temperatures and times, but may not be properly alloyed to produce castings meeting the
minimum properties listed in Table 2. Alloy requirements for the mixed microstructure grades of ADI (Table 2) will be different
than those for the five grades of ADI listed in Table 1.
TABLE 1 Mechanical Property Requirements of Grades 1–5
Grade 1 Grade 2 Grade 3 Grade 4 Grade 5
Inch-pound units
130/90/09 150/110/07 175/125/04 200/155/02 230/185/01
Tensile strength, min, ksi 130 150 175 200 230
Yield strength, min, ksi 90 110 125 155 185
Elongation in 2 in., min, % 9 7 4 2 1
2A
Typical hardness, HBW, kg/mm 269–341 302–375 341–444 388–477 402–512
A
Hardness is not mandatory and is shown for information only.
Grade 1 Grade 2 Grade 3 Grade 4 Grade 5
SI units
900/650/09 1050/750/07 1200/850/04 1400/1100/02 1600/1300/01
Tensile strength, min, MPa 900 1050 1200 1400 1600
Yield strength, min, MPa 650 750 850 1100 1300
Elongation in 50 mm, min, % 9 7 4 2 1
2A
Typical hardness, HBW, kg/mm 269–341 302–375 341–444 388–477 402–512
A
Hardness is not mandatory and is shown for information only.
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A897/A897M − 22
TABLE 2 Mechanical Property Requirements of Mixed
Microstructure Grades
Grade
Inch-pound units
110/70/11
Tensile strength, min, ksi 110
Yield strength, min, ksi 70
Elongation in 2 in., min, % 11
2A
Typical hardness, HBW, kg/mm 241–302
A
Hardness is not mandatory and is shown for information only.
Grade
SI units
750/500/11
Tensile Strength, min, MPa 750
Yield strength, min, MPa 500
Elongation in 50 mm, min, % 11
2A
Typical hardness, HBW, kg/mm 241–302
A
Hardness is not mandatory and is shown for information only.
5. Microstructure
5.1 The graphite component of the microstructure shall consist of a minimum 80 % spheroidal graphite conforming to Types I and
II per Test Method A247.
5.2 The matrix microstructure shall substantially consist of ausferrite (acicular ferrite and high carbon, stable austenite) for Grades
1–5 1 through 5 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 other high temperature
high-temperature transformation products. In some cases, the maximum acceptable quantities of these microconstituents and the
location(s) within the casting may be established by agreement between the manufacturer, heat treater, and the purchaser.
5.4 Martensite may be present in minor amounts in the microstructures of Grades 200/155/02 [1400/1100/02] and 230/185/01
[1600/1300/01]. Acceptable quantities of martensite may be established by agreement between the manufacturer, heat treater, and
the purchaser.
5.5 The microstructure shall be substantially free of undesirable microconstituents, the details of which shall be agreed upon by
the manufacturer, heat treater, and the purchaser.
5.6 The manufacturer, heat treater, and the purchaser may agree upon special chemical compositions or processing requirements
to limit the microconstituents described in 5.3 – 5.5.
6. Mechanical Properties
6.1 Tensile property requirements include tensile strength, yield strength, and elongation and apply only after austempering heat
treatment.
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 determined by the 0.2 % offset method (see Test Methods E8E8/E8M).
6.4 Tensile strength and elongation may degrade with section thicknesses in excess of 1.2 in. [30 mm]. Any deviations to the
minimum properties in Tables 1 and 2 must be agreed upon between the manufacturer, heat treater, and purchaser and specified
in the order for materials purchased to this specification (see Section 3). Guidance for how properties may degrade with increasing
section thickness is provided in Table X1.4.
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7. Hardness
7.1 The area or areas on the castings where hardness is to be checked shall be established by agreement between the manufacturer
and purchaser, or the manufacturer and the end user.
7.2 Brinell hardness shall be determined according to Test Method E10 after sufficient material has been removed from the casting
surface to insureensure representative hardness readings. The 10 mm ball and 3000 kg load shall be used unless otherwise specified
and agreed upon.
8. Special Requirements
8.1 When specified in the contract or purchase order, castings shall meet special requirements as to hardness, chemical
composition, microstructure, pressure tightness, radiographic soundness, magnetic particle inspection, dimensions, and surface
finish. Refer to Specification A834 for a list of common requirements for iron castings not specifically referenced elsewhere in this
specification.
8.2 When specified in the contract or purchase order, castings shall meet special requirements prior to the austempering heat
treatment operation.
9. Heat Treatment
9.1 Castings produced in accordance with this specification to achieve the minimum mechanical properties in Table 1 shall be heat
treated by an austempering process consisting of heating the castings to a fully austenitic, homogeneous condition, cooling (at a
rate usually sufficient to avoid the formation of pearlite) to a temperature above the martensite start temperature, and isothermally
transforming the matrix structure for a time sufficient to produce the desired properties. This process shall produce a microstructure
that is substantially ausferrite.
9.2 Castings produced in accordance with this specification to achieve the minimum mechanical properties in Table 2 shall be heat
treated by an austempering process consisting of heating the castings to an intercritical temperature to produce a fully
homogeneous austenite/ferrite condition, cooling (at a rate usually sufficient to avoid the formation of pearlite) to a temperature
above the martensite start temperature, and isothermally transforming the matrix structure for a time sufficient to produce the
desired 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 specimens described in Section 12 may be machined
prior to the austempering heat treatment. In this case, heat treatment shall be performed in an inert or carbon controlled
carbon-controlled environment so as to prevent carburization, decarburization, or scaling. Handling and fixturing must be such as
to prevent test bar distortion (see X1.4).
9.4 Re-austempering of castings or any deviation from the established heat treating process is only permissable with the approval
of the casting purchaser.
10. Workmanship, Finish, and Appearance
10.1 The surfaces of castings shall be clean and free of adhering molding material, heat 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 the
purchaser.
10.2 Castings shall not have chilledcarbidic corners or center chill (carbides) in areas to be machined.
10.3 Welding repair is not acceptable on austempered castings.
11. Test Coupons
11.1 Separately cast test coupons from which the tension test and Charpy test specimens are machined shall be cast to the size
and 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.
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FIG. 1 Keel Block for Test Coupons
“Y” Block Size
For Castings of For Castings of For Castings of
1 1
Thickness Less Thickness ⁄2 Thickness of 1 ⁄2 in.
Dimensions
1 1
Than ⁄2 in. to 1 ⁄2 in. [13 to 38 [38 mm]
[13 mm] mm] and Over
in. [mm] in. [mm] in. [mm]
A ⁄2 [13] 1 [25] 3 [75]
5 1
B 1 ⁄8 [40] 2 ⁄8 [55] 5 [125]
C 2 [50] 3 [75] 4 [100]
D 4 [100] 6 [150] 8 [200]
E 7 [175] 7 [175] 7 [175]
approx approx approx
9 1 1
F ⁄16 [14] 1 ⁄16 [27] 3 ⁄16 [78]
1 1 1
G 7 ⁄8 [180] 7 ⁄8 [180] 7 ⁄8 [180]
approx approx approx
FIG. 2 Y-Blocks for Test Coupons
[25-mm] 1 in. [25 mm] Y-block or the 1-in. [25-mm] 1 in. [25 mm] keel block. The test coupons shall be cast in open molds made
1 1
of suitable core sand having a minimum wall thickness of 1 ⁄2 in. [38-mm] [38 mm] for the ⁄2-in. [13-mm] and 1-in. [25-mm] in.
[13 mm] and 1 in. [25 mm] sizes and 3 in. [76-mm][76 mm] for the 3-in. [76-mm] 3 in. [76 mm] size. The coupons shall be left
in the mold until they have cooled to a black color (900°F [480°C](900 °F [480 °C] or less). The size and type of coupon cast to
represent the casting shall be at the option of the purchaser. In case no option is expressed, the manufacturer shall make the choice.
11.2 When investment castings are made in accordance with this specification, the manufacturer may use cast-to-size test
specimens that are either incorporated in the mold with the castings or separately cast using the same type of mold and the same
thermal conditions that are used to produce the castings. The test specimens shall be made to the dimensions shown in Fig. 1 of
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FIG. 3 Mold for Modified Keel Block
Specification A732/A732M or Fig. 5 of Test Methods and Definitions A370. The exact procedure to be used for producing test
specimens shall be agreed upon by the manufacturer and the purchaser.
11.3 When castings made in accordance with this specification are produced by nodularization directly in the mold, the
manufacturer may use either separately cast test coupons or test specimens cut from castings. If test bars are to be cut from castings,
test bar location shall be agreed upon by the purchaser and the manufacturer and indicated on the casting drawing. When separately
cast test coupons are used, selection shall be as outlined in 11.1 and shown in Figs. 1-6. Appendix X2 provides guidelines for
selection of coupons with mold cooling rates representative of various casting sections.
11.4 Test coupons shall be poured from the same ladle or heat as the castings they represent and, unless otherwise agreed upon
by the manufacturer and the purchaser, shall be subject to the same post inoculation and alloying practice.
11.5 Test coupons shall be heat treated with the castings they represent.
11.6 The number of test coupons and the number of tests required per order or lot size shall be established at the time of ordering.
This agreement should include a definition of lot size. Lot size can be defined to include the entire order, a specified portion of
that order, a specified manufacturing production period, or a specified quantity of parts shipped to the purchaser.
11.7 If any test specimen shows obvious defects, another may be cut from the same test block or from another test block
representing the same metal. Positions other than “A” or “B” in Fig. 4(a) or Fig. 4(b) or Position “A,” “B,” “C,” or “D” in Fig.
4(c) shall not be used. In those cases where removal of test bars from actual castings has been agreed upon (see 11.2 and 11.311.2
and 11.3), a second test bar may be obtained from an alternate location of equivalent section or from a second casting processed
in the same lot.
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FIG. 4 Sectioning Procedure for Y-Blocks
FIG. 5 Standard Round Tension Test Specimen with 2-in. [50-mm] 2 in. [50 mm] Gage Length
12. Tension Test Specimens
12.1 The standard round tension test specimen with a 2-in. [50-mm] 2 in. [50 mm] gage length shown in Fig. 5 shall be used,
except when the ⁄2-in. [13-mm] in. [13 mm] Y-block coupon is used. In this case, either of the test specimens shown in Fig. 6 shall
be satisfactory. Tension test specimens shall be machined only from PositionsPosition A (preferred) or B in Fig. 4. (a) and Fig. 4(b)
or from Positions A and C (preferred) or B and D in Fig. 4(c). The test bars may be machined before or after heat treatment in
accordance with 9.3.
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FIG. 6 Examples of Small-Size Specimens Proportional to
Standard ⁄2-in. [13-mm] in. [13 mm] Round Specimen
13. Responsibility for Quality and Inspection
13.1 At the time of an order, the purchaser should establish an agreement for quality and inspection requirements with the
manufacturers. The form of this agreement depends upon which of the conditions in 13.2 or 13.3 are determined to exist.
13.2 If all manufacturing operations are performed by a single manufacturer, that manufacturer is responsible for performance of
all quality and inspection requirements covered herein.
13.3 If, at the time of ordering, the purchaser determines that more than one manufacturer will contribute to the casting,
machining, and heat treatment oper
...