ASTM A897-90(1997)
(Specification)Standard Specification for Austempered Ductile Iron Castings (Withdrawn)
Standard Specification for Austempered Ductile Iron Castings (Withdrawn)
SCOPE
1.1 This specification covers ductile iron castings that are subsequently heat treated by an austempering process as defined in 8.1.
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 in this specification are stated in inch-pound units. Note 1-A companion specification, A897M, has been developed in which the values are stated in SI units. Each specification is independent and the mathematical conversions are not exact equivalents.
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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: A 897 – 90 (Reapproved 1997)
Standard Specification for
Austempered Ductile Iron Castings
This standard is issued under the fixed designation A 897; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2 Military Standard:
MIL-STD-129 Marking for Shipment and Storage
1.1 This specification covers ductile iron castings that are
subsequently heat treated by an austempering process as
3. Ordering Information
defined in 8.1.
3.1 Orders for material to this specification shall include the
1.2 The application of the austempering heat treatment
following information:
extends the range of properties achievable in ductile iron
3.1.1 ASTM designation, with year of issue,
castings.
3.1.2 Grade of austempered ductile iron required (see Table
1.3 No precise quantitative relationship can be stated be-
1 and Sections 5 and 6),
tween the properties of the iron in various locations of the same
3.1.3 Chemical composition requirements, if any (see Sec-
casting or between the properties of castings and those of a test
tion 4),
specimen cast from the same iron (see Appendix X1). How-
3.1.4 Heat treated microstructure restrictions (see Section
ever, austempering heat treatment will tend to diminish any
8),
differences in mechanical properties.
3.1.5 Test coupon criteria (see Section 10),
1.4 The production of castings, machining (if required), and
3.1.6 Lot size and tests per lot (see 10.6 and Section 13),
the austempering heat treatments may be performed by differ-
3.1.7 Special requirements, if desired, including hardness,
ent manufacturers, as covered in Section 13. The purchaser
radiographic soundness, magnetic particle inspection, pressure
should establish by contract agreement, at the time of ordering,
tightness, dimensions, or surface finish (see Section 7),
the responsibility of the various parties for meeting the
3.1.8 Certification, if required (see Section 14),
specification requirements.
3.1.9 Special preparation for delivery, if required (see Sec-
1.5 The values in this specification are stated in inch-pound
tion 15).
units.
NOTE 1—A companion specification, A 897M, has been developed in 4. Chemical Composition
which the values are stated in SI units. Each specification is independent
4.1 Although this specification has no specific chemical
and the mathematical conversions are not exact equivalents.
requirements, such requirements may be agreed upon between
the manufacturer and the purchaser.
2. Referenced Documents
2.1 ASTM Standards:
5. Mechanical Properties
A 370 Test Methods and Definitions for Mechanical Testing
5.1 Tensile property requirements include tensile strength,
of Steel Products
yield strength, and elongation and apply only after austemper-
A 732 Specification for Castings, Investment, Carbon and
ing heat treatment.
Low Alloy Steel for General Application, and Cobalt Alloy
5.2 The iron represented by the test specimens shall con-
for High Strength at Elevated Temperatures
form to the requirements as presented in Table 1.
A 834 Specification for Common Requirements for Iron
5.3 The yield strength shall be determined by the 0.2 %
Castings for General Industrial Use
offset method (see Test Methods E 8).
E 8 Test Methods for Tension Testing of Metallic Materials
E 23 Test Methods for Notched Bar Impact Testing of
6. Impact Requirements
Metallic Materials
6.1 The iron represented by the test specimens shall con-
form to the impact properties presented in Table 1.
This specification is under the jurisdiction of ASTM Committee A-4 on Iron
6.2 Impact energy requirements apply only after test mate-
Castings and is the direct responsibility of Subcommittee A04.02 on Malleable and
rial has been austempered. The impact test specimens must be
Ductile Iron Castings.
Current edition approved March 30, 1990. Published July 1990.
Annual Book of ASTM Standards, Vol 01.03.
3 5
Annual Book of ASTM Standards, Vol 01.02. Available from Standardization Documents, Order Desk, Building 4, Section D,
Annual Book of ASTM Standards, Vol 03.01. 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
A 897
TABLE 1 Mechanical Property Requirements of Grades
Grade Grade Grade Grade Grade
125/80/10 150/100/7 175/125/4 200/155/1 230/185/−
Tensile strength, min, ksi 125 150 175 200 230
Yield strength, min, ksi 80 100 125 155 185
A
Elongation in 2 in., min, % 10741 .
B A
Impact energy, ft-lb 75 60 45 25 . . .
2C
Typical hardness, BHN, kg/mm 269–321 302–363 341–444 388–477 444–555
A
Elongation and impact requirements are not specified. Although Grades 200/155/1 and 230/185/− are both primarily used for gear and wear resistance applications,
Grade 200/155/1 has applications where some sacrifice in wear resistance is acceptable in order to provide a limited amount of ductility and toughness.
B
Unnotched charpy bars tested at 72 6 7°F. The values in the table are a minimum for the average of the highest three test values of the four tested samples.
C
Hardness is not mandatory and is shown for information only.
finish ground to required dimensions after heat treatment. adhering molding material, heat treatment oils or salts, cracks,
hot tears, or other injurious defects such as slag and surface
7. Special Requirements
porosity. Dimensions shall conform to drawings or patterns
7.1 When specified in the contract or purchase order,
supplied by the purchaser.
castings shall meet special requirements as to hardness, chemi- 9.2 Castings shall not have chilled corners or center chill in
cal composition, microstructure, pressure tightness, radio-
areas to be machined.
graphic soundness, magnetic particle inspection, dimensions,
10. Test Coupons
and surface finish. Refer to Specification A 834 for a list of
common requirements for iron castings not specifically refer- 10.1 Separately cast test coupons from which the tension
test and charpy test specimens are machined shall be cast to the
enced elsewhere in this specification.
7.2 When specified in the contract or purchase order, 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
castings shall meet special requirements prior to the austem-
1-in. Y-block or the 1-in. keel block. The test coupons shall be
pering heat treatment operation.
cast in open molds made of suitable core sand having a
8. Heat Treatment 1 1
minimum wall thickness of 1 ⁄2 in. for the ⁄2-in. and 1-in. sizes
8.1 Castings produced in accordance with this specification and 3 in. for the 3-in. size. The coupons shall be left in the mold
until they have cooled to a black color (900°F or less). The size
shall be heat treated by an austempering process consisting of
heating the castings to a fully austenitic, homogeneous condi- and type of coupon cast to represent the casting shall be at the
option of the purchaser. In case no option is expressed, the
tion, cooling (at a rate usually sufficient to avoid the formation
of pearlite) to a temperature above the martensite start tem- manufacturer shall make the choice.
10.2 When investment castings are made in accordance with
perature, and isothermally transforming the matrix structure for
a time sufficient to produce the desired properties. This process this specification, the manufacturer may use cast-to-size test
specimens that are either incorporated in the mold with the
shall produce a microstructure that is substantially acicular
ferrite and austenite. castings or separately cast using the same type of mold and the
8.2 The cooling rate within some sections may not be same thermal conditions that are used to produce the castings.
sufficient to avoid the formation of pearlite or other high
temperature transformation products. In such cases, the maxi-
mum acceptable quantities of these microconstituents and the
location(s) within the casting may be established by agreement
between the manufacturer and the purchaser.
8.3 Martensite may be present in the microstructure of
Grade 230/185/−. Acceptable quantities of martensite may be
established by agreement between the manufacturer and the
purchaser.
8.4 The manufacturer and the purchaser may agree upon
special chemical compositions or processing requirements to
limit the microconstituents described in 8.2 and 8.3.
8.5 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, decar-
burization, or scaling. Handling and fixturizing must be such as
to prevent test bar distortion (see X1.4).
9. Workmanship, Finish, and Appearance
9.1 The surfaces of castings shall be clean and free of FIG. 1 Keel Block for Test Coupons
A 897
11. Tension Test Specimens
11.1 The standard round tension test specimen with a 2-in.
gage length shown in Fig. 5 shall be used, except when the
⁄2-in. 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 Positions A (preferred)
or B in Fig. 4. The test bars may be machined before or after
heat treatment in accordance with 8.5.
12. Impact Test Specimens
12.1 The unnotched charpy impact strength shall be deter-
mined according to Test Methods E 23 with the following
“Y” Block Size
variations: Specimens are to be prepared unnotched to dimen-
For Castings of For Castings of For Castings of
Dimensions
1 1 sions in Fig. 9 of Test Methods E 23. Blanks from which test
Thickness Less Thickness ⁄2 in. Thickness of 1 ⁄2in.
1 1
Than ⁄2in. to 1 ⁄2 in. and Over
specimens are machined shall be cut only from Positions A or
B in Fig. 4. Test temperature shall be 72 6 7°F. Four specimens
in. in. in.
shall
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