ASTM A897 - A 897M - 22

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Designation: A897/A897M −22
Standard Speciﬁcation for
Austempered Ductile Iron Castings
1
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 be-
tween 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 differ-
ent 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 nonconformance
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 accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
2
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, Car-
bon 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
E8/E8M Test Methods for Tension Testing of Metallic Ma-
terials
E10 Test Method for Brinell Hardness of Metallic Materials
E23 Test Methods for Notched Bar Impact Testing of Me-
tallic Materials
2.2 Military Standard:
3
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.
3.1.2 Grade of austempered ductile iron required (see Table
1or Table 2 and Section 6).
3.1.3 Chemical composition requirements, if any (see Sec-
tion 4).
3.1.4 Deviations to tensile strength and elongation with
increasing section thickness (see 6.4).
3.1.5 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).
1
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 Oct. 1, 2022. Published October 2022. Originally
approved in 1990. Last previous edition approved in 2016 as A897/A897M – 16.
DOI: 10.1520/A0897_A0897M-22.
2
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.
3
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://
dodssp.daps.dla.mil.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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.
1

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.
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 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 transformation products. In some cases, the maxi-
mum 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 marten-
site may be established by agreement between the
manufacturer, heat treater, and the purchaser.
5.5 The microstructure shall be substantially free of unde-
sirable 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 re-
quirements 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 austemper-
ing heat treatment.
6.2 The iron represented by the test specimens shall con-
form 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 E8/E8M).
6.4 Tensile strength and elongation may degrade with sec-
tion 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 speciﬁ-
cation (see Section 3). Guidance for how properties may
degrade with increasing section thickness is provided in Table
X1.4.
TABLE 1 Mechanical Property Requirements of Grades 1–5
Inch-pound units Grade 1
130/90/09
Grade 2
150/110/07
Grade 3
175/125/04
Grade 4
200/155/02
Grade 5
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 7421
Typical hardness, HBW, kg/mm
2A
269–341 302–375 341–444 388–477 402–512
A
Hardness is not mandatory and is shown for information only.
SI units Grade 1
900/650/09
Grade 2
1050/750/07
Grade 3
1200/850/04
Grade 4
1400/1100/02
Grade 5
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
Typical hardness, HBW, kg/mm
2A
269–341 302–375 341–444 388–477 402–512
A
Hardness is not mandatory and is shown for information only.
TABLE 2 Mechanical Property Requirements of Mixed
Microstructure Grades
Inch-pound units Grade
110/70/11
Tensile strength, min, ksi 110
Yield strength, min, ksi 70
Elongation in 2 in., min, % 11
Typical hardness, HBW, kg/mm
2A
241–302
A
Hardness is not mandatory and is shown for information only.
SI units Grade
750/500/11
Tensile Strength, min, MPa 750
Yield strength, min, MPa 500
Elongation in 50 mm, min, % 11
Typical hardness, HBW, kg/mm
2A
241–302
A
Hardness is not mandatory and is shown for information only.
A897/A897M − 22
2

7. Hardness
7.1 The area or areas on the castings where hardness is to be
checked shall be established by agreement between the manu-
facturer 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 ensure 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, chemi-
cal composition, microstructure, pressure tightness, radio-
graphic soundness, magnetic particle inspection, dimensions,
and surface ﬁnish. Refer to Speciﬁcation A834 for a list of
common requirements for iron castings not speciﬁcally refer-
enced elsewhere in this speciﬁcation.
8.2 When speciﬁed in the contract or purchase order,
castings shall meet special requirements prior to the austem-
pering 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 iso-
thermally 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 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 carbidic corners or center chill
(carbides) in areas to be machined.
10.3 Welding repair is not acceptable on austempered cast-
ings.
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. [25 mm] Y-block or the 1 in. [25 mm] keel block.
The test coupons shall be cast in open molds made of suitable
core sand having a minimum wall thickness of 1
1
⁄
2
in. [38 mm]
for the
1
⁄
2
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 cooled to a black color (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 Speciﬁcation A732/A732M or Fig. 5 of Test Methods
and Deﬁnitions A370. The exact procedure to be used for
FIG. 1 Keel Block for Test Coupons
A897/A897M − 22
3

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摘要：

本规范涵盖ASTM A897/A897M-22标准中指定的马氏体耐磨白口铸铁（也称白口铸铁）的技术要求，主要包括化学成分、硬度、弯曲强度、断裂韧性和金相组织等性能指标。该标准适用于采用双金属铸造工艺制造的深衬、耐磨板、磨球、衬板等抗磨损部件，在矿山、水泥、电力等重磨损工况中应用广泛。该版本更新了元素含量范围，并对热处理状态和检验方法作出更明确的规定。

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