ASTM A437 - A 437M - 26 高温用特殊热处理不锈钢和合金钢涡轮型螺栓的标准规范

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Designation: A437/A437M −26
Standard Speciﬁcation for
Stainless and Alloy-Steel Turbine-Type Bolting Specially
Heat Treated for High-Temperature Service
1
This standard is issued under the ﬁxed designation A437/A437M; 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
2
covers stainless and alloy-steel bolt-
ing material and bolting components specially heat treated for
high-temperature service, such as steam turbine, gas turbine,
and similar uses. See Speciﬁcation A962/A962M for the
deﬁnition of bolting. This material requires special processing
and should not be used in general-purpose applications. Bolt-
ing furnished as bars shall be hot wrought and may be further
processed by centerless grinding or by cold drawing.
1.2 The high-temperature properties of the bolting materials
and components covered by this speciﬁcation are dependent
upon special heat treatment, which is required. Although the
high-temperature properties are not speciﬁed, they are implied
by control of the chemistry, heat treatment, and room-
temperature properties of the bolting material.
1.3 Three levels of bolting strength are covered, designated
Grades B4B, B4C, and B4D.
1.4 The following referenced general requirements are in-
dispensable for application of this speciﬁcation: Speciﬁcation
A962/A962M.
1.5 Supplementary requirements are provided for use at the
option of the purchaser. The supplementary requirements shall
apply only when speciﬁed individually by the purchaser in the
purchase order or contract.
1.6 This speciﬁcation is expressed in both inch-pound units
and in SI units; however, unless the purchase order or contract
speciﬁes the applicable Mspeciﬁcation designation (SI units),
the inch-pound units shall apply.
1.7 The values stated in either SI units or inch-pound units
are to be regarded separately as standard. Within the text, the
SI units are shown in brackets. 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-conformance with the
standard.
1.8 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:
3
A962/A962M Speciﬁcation for Common Requirements for
Bolting Intended for Use at Any Temperature from Cryo-
genic to the Creep Range
E292 Test Methods for Conducting Time-for-Rupture Notch
Tension Tests of Materials
E112 Test Methods for Determining Average Grain Size
3. Ordering Information
3.1 It shall be the responsibility of the purchaser to specify
all requirements necessary for product under this speciﬁcation.
Such requirements to be considered include, but are not limited
to, the following:
3.1.1 Speciﬁcation designation, grade, issue date, and revi-
sion letter,
3.1.2 Quantity (weight or number of pieces),
3.1.3 Description (bars, bolts, nuts, etc.),
3.1.4 Dimensions,
3.1.5 Finish, and
3.1.6 Impact testing of nuts, if required (see Section 8).
4. Common Requirements
4.1 Bolting materials and bolting components supplied to
this speciﬁcation shall conform to the requirements of Speci-
ﬁcation A962/A962M. These requirements include test
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
A01.22 on Steel Forgings and Wrought Fittings for Piping Applications and Bolting
Materials for Piping and Special Purpose Applications.
Current edition approved Feb. 1, 2026. Published February 2026. Originally
approved in 1959. Last previous edition approved in 2021 as A437/A437M – 15
(2021). DOI: 10.1520/A0437_A0437M-26.
2
For ASME Boiler and Pressure Vessel Code applications see related Speciﬁ-
cation SA-437 in Section II of that code.
3
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.
*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

methods, ﬁnish, thread dimensions, macroetch (Grade B4D
only), marking, certiﬁcation, optional supplementary
requirements, and others. Failure to comply with the require-
ments of Speciﬁcation A962/A962M constitutes nonconfor-
mance with this speciﬁcation. In case of conﬂict between this
speciﬁcation and Speciﬁcation A962/A962M, this speciﬁcation
shall prevail.
5. Heat Treatment
5.1 Grades B4B and B4C shall be heated to a temperature
range of 1875 to 1925 °F [1024 to 1052 °C] and liquid
quenched to below 600 °F [316 °C]. The material Grades B4B
and B4C shall then be uniformly reheated for tempering at a
tempering temperature at least 100 °F [55 °C] higher than the
proposed operating temperature but not less than 1150 °F [621
°C], then air or furnace cooled to room temperature. The
material shall be at the tempering temperature for a minimum
of 2 h. Double tempering may be used to enhance properties.
5.2 Grade B4D shall be heated to a temperature range of
1700 to 1750 °F [927 to 954 °C] and oil quenched. The
material shall then be uniformly reheated or tempered at a
temperature of 1200 °F [649 °C] minimum, followed by air or
furnace cooling to room temperature.
5.3 Stress relieving treatment of the bar material is required
after any stretcher, roller, or rotary-straightening or cold-
ﬁnishing operations performed after heat treatment for me-
chanical properties. Local gagging or press straightening to
correct camber limitations in excess of 0.25 in. in any 5 ft [6.5
mm in any 1.5 m] shall be followed by a stress relieving heat
treatment. The minimum stress relieving temperature shall be
100 °F [55 °C] below the minimum tempering temperature as
shown in 5.1 for Grades B4B and B4C or in 5.2 for Grade
B4D.
6. Chemical Composition
6.1 Bolting material shall conform to the requirements as to
chemical composition speciﬁed in Table 1.
7. Tensile Requirements
7.1 Bolting material shall conform to the requirements as to
tensile properties prescribed in Table 2 at room temperature
after heat treatment.
7.2 The longitudinal axis of the test specimen shall be
parallel to the direction of rolling.
8. Impact Requirements
8.1 Grades B4B, B4C, and B4D shall conform to the
requirements as to impact properties prescribed in Table 3 at
room temperature after heat treatment.
9. Hardness Tests
9.1 Grades B4B, B4C, and B4D shall conform to the
requirements as to hardness as prescribed in Table 4 and Table
5at room temperature after heat treatment.
10. Nuts
10.1 When speciﬁed by the purchaser, nuts shall be subject
to the impact and tension requirements of this speciﬁcation.
The tests shall be made on test specimens taken from the bar or
plate used in the manufacture of the nuts.
11. Threads
11.1 All threads shall be formed after heat treatment.
12. Nondestructive Inspection
12.1 Each bar or forged blank of starting material shall be
subjected to NDE following ﬁnal heat treatment. The method
used shall be either the Eddy Current (EC), the Magnetic
Particle (MPI) (wet or dry), the Liquid Penetrant (LPI), the
Ultrasonic (UT), or the Visual Testing (VT), at the option of the
manufacturer. For LPI or MPI, linear indications (those indi-
cations longer than 0.06 in. [1.5 mm] with a length greater than
three times their width) are unacceptable. For UT or ET, reject
levels for linear indications shall be based on the alarm
response from a surface notch with a maximum depth of 0.012
in. [0.30 mm] in a calibration bar. Product being subjected to
VT shall be pickled prior to inspection. VT indications longer
than 0.12 in. [3.0 mm] are prohibited.
13. Certiﬁcation
13.1 Certiﬁcation is required. See Speciﬁcation A962/
A962M.
TABLE 1 Chemical Requirements
A
Element Grades B4B, B4C
B
Grade B4D
Range, % Product
Variation, %,
Over or
Under
Range, % Product
Variation, %,
Over or
Under
Carbon 0.20–0.25 0.02 0.36–0.44 0.02
Manganese 0.50–1.00 0.03 0.45–0.70 0.03
Phosphorus, max 0.025 0.005 over 0.04 0.005 over
Sulfur, max 0.025 0.005 over 0.04 0.005 over
Silicon 0.20–0.50 0.05 0.20–0.35 0.02
Nickel 0.50–1.00 0.03 ... ...
Chromium 11.0–12.5 0.15 0.80–1.15 0.05
Molybdenum 0.90–1.25 0.05 0.50–0.65 0.03
Vanadium 0.20–0.30 0.03 0.25–0.35 0.03
Tungsten 0.90–1.25 0.05 ... ...
Aluminum, max
C
0.05 ... 0.015 ...
Titanium, max 0.05 ... ... ...
Tin, max 0.04 ... ... ...
A
Steel to which lead has been added shall not be used.
B
UNS S42200.
C
Total, Soluble + Insoluble
TABLE 2 Tensile Requirements
Grade Diameter, in. [mm] Tensile
Strength,
min, ksi
[MPa]
Yield
Strength
(0.2 %
offset) min,
ksi [MPa]
Elongation
in 2 in. or
50 mm,
min, %
Reduction
of Area,
min, %
B4B ... 145 [1000] 105 [725] 13 30
B4C ... 115 [795] 85 [585] 18 50
B4D 2
1
⁄
2
[65] and under 125 105 18 50
[860] [725]
over 2
1
⁄
2
to 4 [65 to
100]
110
[760]
95
[655]
17 45
over 4 to 7 [100 to
180]
100
[690]
85
[585]
16 45
A437/A437M − 26
2

14. Product Marking

14.1 Use the grade symbol shown in Table 4. See Speciﬁ-

cation A962/A962M.

15. Keywords

15.1 bolts—steel; chromium alloy steel; bolting

components—steel; marking on bolting components; nuts—

steel; stainless steel; steel bars—alloy; steel bolting material;

temperature service applications—high; turbine materials

SUPPLEMENTARY REQUIREMENTS

One or more of the following supplementary requirements shall be applied only when speciﬁed by

the purchaser in the inquiry, contract, or order; in which event the speciﬁed tests shall be made before

shipment of the product.

S1. Non-Destructive Examination

S1.1 NDE is required following all machining and thread-

ing. The acceptance criteria of 12.1 shall apply.

S2. Stress Rupture Testing—Grade B4B

S2.1 Stress rupture testing shall be conducted at 1200 °F

[649 °C] and 26 ksi [180 MPa] using a combination test bar in

accordance with Test Methods E292. Rupture shall occur in the

smooth section of each test specimen. The test may be

discontinued after 25 h provided the certiﬁcation so notes.

Stress rupture testing is not required on bars less than 0.5 in.

[12.7 mm] in diameter or thickness.

S3. Grain Size—Grades B4B and B4C

S3.1 The average grain size shall be 4 or ﬁner. The

maximum size of individual grains, distributed at random, shall

be a 2. When the average grain size is 5 or ﬁner, only the

average size need be reported. Grain size determination shall

be performed in accordance with Test Methods E112.

SUMMARY OF CHANGES

Committee A01 has identiﬁed the location of selected changes to this standard since the last issue

(A437/A437M – 15 (2021)) that may impact the use of this standard. (Approved Feb. 1, 2026.)

(1) Revised Section 5,Table 2,12.1, and S2.1.

ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned

in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk

of infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every ﬁve years and

if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards

and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the

responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should

make your views known to the ASTM Committee on Standards, at the address shown below.

This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,

United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above

address or at 610-832-9585 (phone), or through the ASTM website (www.astm.org/contact). Permission rights to photocopy the

standard may also be secured from the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600;

http://www.copyright.com/

TABLE 3 Impact Requirements

Grade Minimum Impact Value, ft·lbf [J]

B4B 10 [14]

B4C 25 [34]

B4D

25 [34]

For bars over 5-in. [127-mm] diameter only.

TABLE 4 Hardness Requirements for Bolts and Studs

Grade Brinell Hardness Number,

max

B4B 331

B4C 277

B4D 302

TABLE 5 Hardness Requirements for Nuts and Washers

Grade Brinell Hardness

Number

Rockwell

Hardness

Number

B4B 293–341 C 31–37

B4C 229–277 C 21–29

B4D 263–311 C 27–33

A437/A437M − 26

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摘要：

ASTM A437 - A 437M - 26《高温用特殊热处理不锈钢和合金钢涡轮型螺栓的标准规范》是国际权威材料标准，专为燃气轮机、蒸汽轮机等高温高压工况下的涡轮型螺栓紧固件而制定。该规范涵盖了经特殊热处理工艺制造的马氏体不锈钢和沉淀硬化合金钢，确保其在持续高温环境中保持优异的抗蠕变、抗松弛、抗疲劳及耐氧化性能。标准明确规定了材料的化学成分、力学性能（如室温及高温拉伸强度、屈服强度、伸长率、断面收缩率）、硬度范围、金相组织要求，以及严格的特殊热处理方法（包括淬火、回火、时效处理等）和检验规则，

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ASTM A437 - A 437M - 26 高温用特殊热处理不锈钢和合金钢涡轮型螺栓的标准规范

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