ASTM A1091 - A 1091M - 24 高温承压部件用蠕变强度增强铁素体合金钢铸件标准规范

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Designation: A1091/A1091M −24
Standard Speciﬁcation for
Steel Castings, Creep-Strength Enhanced Ferritic Alloy, for
Pressure-Containing Parts, Suitable for High-Temperature
Service
1
This standard is issued under the ﬁxed designation A1091/A1091M; 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 creep-strength enhanced alloy
steel castings for valves, ﬂanges, ﬁttings, and other pressure-
containing parts intended primarily for high-temperature ser-
vice (see Note 1). However, they are not restricted to such
applications and the castings may be used for other applica-
tions for which the attributes of the material, as deﬁned by this
speciﬁcation, are suitable.
1.2 Two grades of martensitic alloy steel, Grade C91 (UNS
No. J84090) and Grade C933 (UNS No. J84093), are covered.
Grade C91 is provided in two classes, differentiated by the type
of heat treatment after welding. Both grades, and similar steels,
are characterized by a predominantly tempered martensitic or
tempered bainitic microstructure that is stabilized by the
precipitation of temper-resistant particles at various precipitate
nucleation sites in the microstructure. Such steels are designed
to have creep-rupture strengths signiﬁcantly superior to those
of alloys of nominally similar compositions, but in which the
precipitates or nucleation sites are absent. Since this crucial
difference cannot be revealed by room temperature mechanical
property tests, these alloys require tighter controls on manu-
facturing and processing.
NOTE 1—The grades covered by this speciﬁcation represent materials
that are generally suitable for assembly with other castings or wrought
steel parts by fusion welding. It is not intended to imply that these grades
possess equal degrees of weldability; therefore, it is the responsibility of
the purchaser to establish a suitable welding technique. Since these grades
possess varying degrees of suitability for high-temperature service, it is
also the responsibility of the purchaser to determine which grade shall be
furnished, due consideration being given to the requirements of the
applicable construction codes.
1.3 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.
1.4 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
A703/A703M Speciﬁcation for Steel Castings, General
Requirements, for Pressure-Containing Parts
A802/A802M Practice for Steel Castings, Surface Accep-
tance Standards, Visual Examination
A985/A985M Speciﬁcation for Steel Investment Castings
General Requirements, for Pressure-Containing Parts
A999/A999M Speciﬁcation for General Requirements for
Alloy and Stainless Steel Pipe
2.2 ANSI Standard:
3
ANSI B46.1 Surface Texture
2.3 ASME Boiler and Pressure Vessel Code:
4
ASME Boiler and Pressure Vessel Code Section I
ASME Boiler and Pressure Vessel Code Section III
ASME Boiler and Pressure Vessel Code Section IV
ASME Boiler and Pressure Vessel Code Section VIII
ASME Boiler and Pressure Vessel Code Section IX
ASME Boiler and Pressure Vessel Code Section XII
2.4 Other ASME Codes:
4
B16.34 Valves Flanged, Threaded and Welding End
B31.1 Power Piping
1
This speciﬁcation is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.18 on Castings.
Current edition approved July 1, 2024. Published July 2024. Originally approved
in 2016. Last previous edition approved in 2021 as A1091/A1091M – 21. DOI:
10.1520/A1091_A1091M-24.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at www.astm.org/contact. For Annual Book of
ASTM Standards volume information, refer to the standard’s Document Summary
page on the ASTM website.
3
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org.
4
Available from American Society of Mechanical Engineers (ASME), ASME
International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
www.asme.org.
*A Summary of Changes section appears at the end of this standard
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

B31.3 Process Piping
2.5 AWS Speciﬁcations:
5
A5.5/A5.5M Low-Alloy Steel Electrodes for Shielded Metal
Arc Welding
A5.23/A5.23M Low-Alloy Steel Electrodes and Fluxes for
Submerged Arc Welding
A5.28/A5.28M Low-Alloy Steel Electrodes and Rods for
Gas Shielded Arc Welding
A5.29/A5.29M Low-Alloy Steel Electrodes for Flux Cored
Arc Welding
3. General Conditions for Delivery
3.1 Except for investment castings and centrifugally cast
pipe, castings furnished to this speciﬁcation shall conform to
the requirements of Speciﬁcation A703/A703M, including any
supplementary requirements that are indicated in the purchase
order. Failure to comply with the general requirements of
Speciﬁcation A703/A703M constitutes nonconformance with
this speciﬁcation. In case of conﬂict between the requirements
of this speciﬁcation and Speciﬁcation A703/A703M, this
speciﬁcation shall prevail.
3.2 Investment castings furnished to this speciﬁcation shall
conform to the requirements of Speciﬁcation A985/A985M,
including any supplementary requirements that are indicated in
the purchase order. Failure to comply with the general require-
ments of Speciﬁcation A985/A985M constitutes nonconfor-
mance with this speciﬁcation. In case of conﬂict between the
requirements of this speciﬁcation and Speciﬁcation A985/
A985M, Speciﬁcation A985/A985M shall prevail.
3.3 Centrifugally cast pipe furnished under this speciﬁcation
shall conform to the requirements of Speciﬁcation A999/
A999M, including any supplementary requirements that are
indicated in the purchase order. Failure to comply with the
general requirements of Speciﬁcation A999/A999M consti-
tutes nonconformance with this speciﬁcation. In case of con-
ﬂict between the requirements of this speciﬁcation and Speci-
ﬁcation A999/A999M, this speciﬁcation shall prevail.
4. Ordering Information
4.1 Orders for material under this speciﬁcation shall include
the following, as required, to describe the desired material
adequately:
4.1.1 Except for centrifugally cast pipe:
4.1.1.1 A description of the casting by pattern number or
drawing (dimensional tolerances shall be included on the
casting drawing),
4.1.1.2 Grade and class of steel,
4.1.1.3 Options in the speciﬁcation (see 5.1.5,5.2,7.1.4,
8.4,10.3.5, and 10.3.7,10.3.8.2, and 10.3.8.3),
4.1.1.4 Whether the castings are to be produced using the
investment casting process, and
4.1.1.5 The supplementary requirements desired including
the standards of acceptance.
4.1.2 Centrifugally cast pipe:
4.1.2.1 Quantity (feet, centimeters, or number of lengths),
4.1.2.2 Name of material (centrifugally cast pipe),
4.1.2.3 Grade of steel,
4.1.2.4 Size (outside or inside diameter and minimum wall
thickness),
4.1.2.5 Length (speciﬁc or random) (Section on Permissible
Variations in Length of Speciﬁcation A999/A999M),
4.1.2.6 End ﬁnish (Section on Ends of Speciﬁcation A999/
A999M),
4.1.2.7 Options in the speciﬁcation (see 5.1.5,5.2,7.1.4,
8.4,10.3.5, and 10.3.7,10.3.8.2, and 10.3.8.3),
4.1.2.8 Whether the castings are to be used in ASME Boiler
and Pressure Vessel Code Sections I, III, IV, VIII, and XII
construction; or in ASME Codes B16.34, B31.1, B31.3, or
other ASME construction codes, and
4.1.2.9 The supplementary requirements desired.
5. Materials and Manufacture
5.1 Heat Treatment—Grades shall be furnished in the aus-
tenitized and tempered condition. Before heat treatment, cast-
ings shall be allowed to cool to a temperature below the
transformation range.
5.1.1 Grade C91 shall be heat treated by heating to a
temperature range of 1900 to 1975 °F [1040 to 1080 °C] and
either air cooled or accelerated cooled from the austenitizing
temperature by air blasting or liquid quenching, to a tempera-
ture of 200 °F [95 °C] or below, followed by tempering at 1350
to 1470 °F [730 to 800 °C].
5.1.2 Grade C933 shall be heat treated by heating to a
temperature range of 2010 to 2190 °F [1100 to 1200 °C] and
either air cooled or accelerated cooled from the austenitizing
temperature by air blasting or liquid quenching to a tempera-
ture of 200 °F [95 °C] or below, followed by tempering at 1350
to 1440 °F [730 to 780 °C].
5.1.3 Compliance with the temperature ranges speciﬁed in
5.1.1 and 5.1.2 for castings heat treated singly shall be veriﬁed
by a thermocouple or thermocouples placed directly on the
castings.
5.1.4 Compliance with the temperature ranges speciﬁed in
5.1.1 and 5.1.2 for castings heat treated in batches shall be
veriﬁed by thermocouples placed on selected castings in each
batch.
5.1.5 Unless speciﬁed by the purchaser, the number and
locations of thermocouples to be placed on each casting, or on
castings in each heat-treatment batch, shall be at the discretion
of the producer.
5.1.6 A record of the ﬁnal austenitizing and tempering heat
treatment and, if speciﬁed in the order (see 10.3.7) of any and
all subsequent subcritical heat treatments, shall be made and
shall be shown on the material test report. The record shall
include both the number and locations of thermocouples
applied to each casting, or to each heat-treatment batch of
castings.
5.2 Machining—Centrifugally cast pipe shall be machined
on the inner and outer surfaces to a roughness value no greater
than 250 µin. [6.35 µm] arithmetical average deviation (AA)
from the mean line unless otherwise speciﬁed as in ANSI
B46.1.
5
Available from American Welding Society (AWS), 8669 NW 36 St., #130,
Miami, FL 33166-6672, http://www.aws.org.
A1091/A1091M − 24
2

6. Chemical Composition
6.1 The steel shall conform to the requirements speciﬁed in
Table 1 (see Note 2).
NOTE 2—The role of alloying elements in the development of Grade
C91 has been extensively investigated. V and Cb (Nb) contribute to
precipitation strengthening by forming ﬁne and coherent precipitation of
M(C, N)X carbo-nitrides in the ferrite matrix. V also precipitates as VN
during tempering or during creep. The two elements are more effective in
combination. Therefore, the addition of strong nitride-forming elements,
those with a stronger affinity for nitrogen than Cb (Nb) and V, as
de-oxidation agents interferes with these high-temperature strengthening
mechanisms.
6
Grade C933 also requires V and Nb to contribute to
precipitation strengthening along with a strong dependence on Boron and
Nitrogen levels. Consequently, the addition of strong nitride-forming
elements with stronger affinity for nitrogen than Nb, V, and B must also be
avoided.
7. Mechanical Properties
7.1 Tensile Testing:
7.1.1 One tension test shall be made from each heat per heat
treatment lot. Test results shall conform to the tensile require-
ments speciﬁed in Table 2.
7.1.2 If a specimen is machined improperly or if ﬂaws are
revealed by machining or during testing, the specimen may be
discarded and another substituted from the same heat.
7.1.3 Except as permitted by 7.1.4, and except for invest-
ment castings, test coupons from which tension test specimens
are prepared shall be removed from heat-treated casting
prolongations.
7.1.4 When agreed upon between the manufacturer and the
purchaser, test coupons from which test specimens are pre-
pared shall be cast as separate blocks from the same heat as the
casting represented. The test blocks shall be heat treated in the
same manner as the casting represented.
7.2 Hardness Testing—Each casting shall be tested in ac-
cordance with Supplementary Requirement S13 of Speciﬁca-
tion A703/A703M or A985/A985M for investment castings
and shall have a Brinell hardness of 185 to 248 HBW for Grade
C91 castings, or 195 to 270 HBW for Grade C933.
8. Quality
8.1 All accessible surfaces of the castings shall be examined
visually and shall be free of adhering sand, scale, cracks, and
hot tears. Other surface discontinuities shall meet the visual
acceptance standards speciﬁed in the order. Practice A802/
A802M or other visual standards may be used to deﬁne
acceptable surface discontinuities and ﬁnish. Unacceptable
visual surface discontinuities shall be removed and their
removal veriﬁed by visual examination of the resultant cavi-
ties. When methods involving high temperatures are used in
the removal of discontinuities, castings shall be preheated to at
least 400 °F [200 °C].
8.2 Except for centrifugally cast pipe, hollow castings larger
than NPS 4 [DN 100] and whose internal surfaces are not
accessible to the visual examination in 8.1 shall be examined
by the ultrasonic examination prescribed in Supplementary
Requirement S7 of Speciﬁcation A703/A703M; or for invest-
ment castings, Supplementary Requirement S7 of Speciﬁcation
A985/A985M.
8.2.1 Castings producing a signal equal to or greater than
the lowest signal produced by the referenced discontinuities
shall be considered to contain defects, and they shall be
identiﬁed and separated from the acceptable castings. The area
producing the signal may be re-examined.
8.2.2 Castings containing defects shall be rejected if the test
signals were produced by imperfections that cannot be identi-
ﬁed or were produced by cracks or crack-like imperfections.
8.2.3 Castings containing defects may be repaired. To be
accepted, a repaired casting shall pass the ultrasonic examina-
tion and shall meet the minimum wall thickness requirements
of the purchase order.
8.3 Each length of centrifugally cast pipe shall be ultrasoni-
cally examined in accordance with Speciﬁcation A999/
A999M.
8.4 When additional inspection is desired, Supplementary
Requirements S4, S5, S6, and S10 of Speciﬁcation A703/
A703M; or, for investment castings, Speciﬁcation A985/
A985M, may be ordered.
6
Viswanathan, R. and Bakker, W. T., Materials for Ultra Supercritical Fossil
Power Plants, EPRI, Palo Alto, CA, 2000. TR-114750.
TABLE 1 Chemical Composition Requirements
A,B
Element
Weight %
Grade C91
J84090
Grade C933
N07130
Carbon 0.08–0.12 0.09–0.13
Manganese 0.30–0.60 0.30–0.75
Phosphorus 0.025 0.025
Sulfur 0.010 0.012
Silicon 0.20–0.50 0.60
Nickel 0.40 0.40
Chromium 8.0–9.5 8.0–9.5
Molybdenum 0.85–1.05 0.30
Niobium 0.060–0.10 0.05–0.10
Nitrogen 0.030–0.070 0.010–0.020
Vanadium 0.18–0.25 0.18–0.25
Aluminum 0.02 0.02
Titanium 0.01 0.01
Zirconium 0.01 0.01
Cobalt . . . 2.75–3.50
Tungsten . . . 2.25–3.00
Boron . . . 0.007–0.019
A
All values are maximums unless a range is provided.
B
Where ellipses (...) appear in this table, there is no requirement, and the element
need not be analyzed for or reported.
TABLE 2 Tensile Requirements
A
Grade
(UNS Number)
Tensile
Strength,
ksi [MPa]
Yield
Strength,
B
ksi [MPa]
Elongation in
2 in. [50 mm.],
%
C
Reduction of
Area, %
C91
(J84090)
85–110
[585–760] 60 [415] 18 45
C933
N07130
100–125
[680–860] 80 [550] 16 35
A
All values are minimums unless a range is provided.
B
Determined by 0.2 % offset method.
C
When ICI test bars are used in tensile testing as provided for in Speciﬁcation
A703/A703M or A985/A985M for investment castings, the gauge length to reduced
section diameter ratio shall be 4 to 1.
A1091/A1091M − 24
3

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ASTM A 1091/A1091M-2024 Standard Specification for Steel Castings, Creep-Strength Enhanced Ferritic Alloy, for Pressure-Containing Parts, Suitable for High-Temperature Service 高温承压部件用蠕变强度增强铁素体合金钢铸件标准规范

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ASTM A1091 - A 1091M - 24 高温承压部件用蠕变强度增强铁素体合金钢铸件标准规范

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