ASTM A723/A723M-18a(2023)

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.
Designation: A723/A723M − 18a (Reapproved 2023)
Standard Specification for
Alloy Steel Forgings for High-Strength Pressure Component
Application
This standard is issued under the fixed designation A723/A723M; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This specification covers requirements for high-
A275/A275M Practice for Magnetic Particle Examination of
strength quenched and tempered alloy steel forgings for pres-
Steel Forgings
sure vessels, isostatic presses, shock tubes, and similar com-
A370 Test Methods and Definitions for Mechanical Testing
ponents.
of Steel Products
1.2 These materials are not intended for welded construc-
A388/A388M Practice for Ultrasonic Examination of Steel
tion.
Forgings
A788/A788M Specification for Steel Forgings, General Re-
1.3 Three grades of nickel-chromium-molybdenum steels
quirements
and six classes of increasing tensile strength are included. The
2.2 Other Standard:
strength class, section size, and configuration of the forging
ASME Boiler and Pressure Vessel Code
will largely dictate the applicable type(s) of steel.
3. Ordering Information and General Requirements
1.4 The values stated in either inch-pound units or SI
(metric) units are to be regarded separately as the standard.
3.1 In addition to the ordering information required by
Within the text and tables, the SI units are shown in brackets.
Specification A788/A788M, the purchaser shall include with
The values stated in each system are not exact equivalents; the inquiry and order a detailed drawing, sketch, or written
therefore, each system must be used independently of the other. description of the forging and the method of selecting test
location (see 6.2). When appropriate, the areas of significant
Combining values from the two systems may result in noncon-
loading in the forging shall be designated. The purchaser may
formance with the specification.
also include appropriate supplementary requirements from
1.5 Unless the order specifies the applicable “M” specifica-
Specification A788/A788M as well as from this specification.
tion designation, the material shall be furnished to the inch-
3.2 Material supplied to this specification shall conform to
pound units.
the requirements of Specification A788/A788M, which out-
1.6 This international standard was developed in accor-
lines additional ordering information, manufacturing
dance with internationally recognized principles on standard-
requirements, testing and retesting methods and procedures,
ization established in the Decision on Principles for the
marking, certification, product analysis variations, and addi-
Development of International Standards, Guides and Recom- tional supplementary requirements.
mendations issued by the World Trade Organization Technical
3.3 If the requirements of this specification are in conflict
Barriers to Trade (TBT) Committee.
with the requirements of Specification A788/A788M, the
requirements of this specification shall prevail.
3.4 When forgings are required to be in compliance with
Division 3 of the ASME Boiler and Pressure Vessel Code,
Supplementary Requirement S6 should be specified.
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee For referenced ASTM standards, visit the ASTM website, www.astm.org, or
A01.06 on Steel Forgings and Billets. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved March 15, 2023. Published April 2023. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 1975. Last previous edition approved in 2018 as A723/A723M – 18a. the ASTM website.
DOI: 10.1520/A0723_A0723M–18AR23. Available from American Society of Mechanical Engineers (ASME), ASME
For ASME Boiler and Pressure Vessel Code applications see related Specifi- International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
cation SA–723/SA–723M in Section II of that Code. www.asme.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A723/A723M − 18a (2023)
4. Materials and Manufacture tension test specimen as specified in Test Methods and Defi-
nitions A370 (that is, standard round 0.500 in. [12.5 mm]
4.1 Melting Practice—The steel melting procedures of
diameter specimen) shall be used. Charpy V-notch Type A
Specification A788/A788M shall apply except that the open-
impact specimens, as shown in Test Methods and Definitions
hearth process shall not be used, and that the steel shall be
A370, shall be used.
vacuum degassed prior to or during the pouring of the ingot, in
order to remove objectionable gases, particularly hydrogen.
6.2 Sampling—The mid-point of the gage length of tension
4.1.1 Use of secondary remelting or refining operations may
test specimens and the area under the notch of impact speci-
be considered for particularly demanding applications.
mens shall be located in accordance with one of the following
4.2 Discard—Sufficient discard shall be taken from each methods as specified by the purchaser, or suggested by the
supplier and approved by the purchaser. Wherever practical, all
ingot to secure freedom from piping and excessive segregation.
testing shall be from integral prolongations of the forging.
4.3 Heat Treatment:
6.2.1 Method 1—This method shall always be used when
4.3.1 Forgings shall be rough-machined prior to final heat
the maximum quenched thickness does not exceed 4 in.
treatment if it is necessary to reduce the mass to ensure full
[100 mm]. Datum points of the specimens, as described in 6.2,
hardening or to meet the requirements of 6.2. The risk of
shall be located in the forging or test forging (6.2.4) at
cracking during heat treatment with high-hardenability steels
mid-thickness and at least ⁄3 T (T is the maximum heat-treated
of the type covered by this specification should be borne in
thickness) from the quenched end surface or nearest adjacent
mind when deciding on the degree of surface preparation
before heat treatment. surfaces.
4.3.2 Heat Treatment for Mechanical Properties—Heat
6.2.2 Method 2—t by 2t, where t is the distance from the
treatment shall consist of normalizing (which may be part of
area of significant loading (3.1) to the nearest quenched
the preliminary treatment), reaustenitization, liquid quenching,
surface. However, the datum points of the specimens as
and tempering. The forgings shall be quenched in a suitable
described in 6.2 shall not be nearer to one quenched surface
liquid medium by spraying or immersion. Quenching shall be
than ⁄4 in. [20 mm] and to the second quenched surface than
followed by tempering at a minimum temperature of 1000 °F 1
1 ⁄2 in. [40 mm]. When this method of testing is employed,
[540 °C]. The minimum time at tempering temperature shall be
forgings are usually manufactured in accordance with a
1 1
⁄2 h/in. [ ⁄2 h/25 mm] of maximum section thickness, unless
purchaser-approved drawing showing prequenched dimensions
otherwise agreed between supplier and purchaser.
and the location of mechanical test specimens. It is commonly
used for disk-type forgings such as tube sheets and covers.
5. Chemical Composition
6.2.3 Method 3—For maximum quenched thicknesses in
5.1 Heat Analysis—The heat analysis obtained from sam-
excess of 4 in. [100 mm] as heat-treated. Where this method of
pling in accordance with Specification A788/A788M shall
testing is employed, the datum points of the test specimen, as
comply with Table 1.
described in 6.2, shall be removed ⁄4 T from the nearest
5.1.1 Temper Embrittlement Control—The purchaser’s at-
quenched surface and ⁄3 T from the quenched end surface or
tention is drawn to Supplementary Requirement S24 in Speci-
nearest adjacent surface.
fication A788/A788M for application of the J Factor which
6.2.4 Method 4—Test specimens shall be taken from a
may be of assistance in the control of temper embrittlement in
representative separate test forging made from the same heat of
forgings produced to Specification A723/A723M.
steel, which shall receive substantially the same reduction and
5.2 Product Analysis—The manufacturer shall use the prod-
type of hot working, and have a cross section not less than the
uct analysis provision of Specification A788/A788M to obtain
production forgings which it represents. It shall be heat-treated
a product analysis from a forging representing each heat or
in the same furnace charge and under the same conditions as
multiple heat. The purchaser may also make this determination
the production forgings. The test specimen shall be removed
in accordance with Specification A788/A788M.
using the Method 3 procedure.
6. Mechanical Properties
6.3 Thermal Buffers:
6.1 General Requirements—The forging shall conform to
6.3.1 Thermal buffer rings, at least T by T in cross section or
the requirements of Table 2 and Table 3. The largest obtainable
sections of such a ring at least 3 T in length, shall be welded to
the test end(s) of a forging prior to heat treatment for
TABLE 1 Chemical Requirements
mechanical properties. The buffer material may be any weld-
Composition, %
able carbon or low-alloy steel and shall be joined to the forging
Grade 1 Grade 2 Grade 3
with a partial penetration-type weld which completely seals the
Carbon, max 0.35 0.40 0.40
buffered surface. The test coupons shall be removed from the
Manganese, max 1.00 0.90 0.90
Phosphorus, max 0.015 0.015 0.015
forging in the region buffered by the ring or ring segments. If
Sulfur, max 0.015 0.015 0.015
the latter are used, the test coupons shall be removed from the
Silicon, max 0.35 0.35 0.35
forging in the area under the center ⁄3 of the buffer ring
Nickel 1.5 to 2.25 2.3 to 3.3 3.3 to 4.5
Chromium 0.80 to 2.00 0.80 to 2.00 0.80 to 2.00
segment length. In either case, the test specimens shall be
Molybdenum 0.20 to 0.50 0.30 to 0.60 0.40 to 0.80
located at a minimum distance of ⁄2 in. [13 mm] from the
Vanadium, max 0.20 0.20 0.20
buffered surface of the forging and at least ⁄4 T from a
A723/A723M − 18a (2023)
TABLE 2 Tensile Requirements
A B C
Class 1 Class 2 Class 2a Class 3 Class 4 Class 5
Tensile strength, min, ksi [MPa] 115 [795] 135 [930] 145 [1000] 155 [1070] 175 [1205] 190 [1310]
Yield strength, 0.2 % offset, min, ksi [MPa] 100 [690] 120 [825] 130 [895] 140 [965] 160 [1105] 180 [1240]
Elongation in 2 in. or 50 mm, min, % 16 14 13.5 13 12 10
Reduction of area, min, % 50 45 43 40 35 30
A
Typical maximum section size of 10 in. [255 mm] for open-ended vessels, or 7 in. [180 mm] for blind-ended vessels.
B
Typical maximum section size of 6 in. [150 mm] for open-ended vessels, or 4 in. [10
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