Designation: A 266/A 266M – 99 An American National Standard

Standard Specification for

Carbon Steel Forgings for Pressure Vessel Components1
This standard is issued under the fixed designation A 266/A 266M; 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.

This standard has been approved for use by agencies of the Department of Defense.

1. Scope E 165 Test Method for Liquid Penetrant Examination6

1.1 This specification2 covers four grades of carbon steel E 381 Method of Macroetch Testing Steel Bars, Billets,
forgings for boilers, pressure vessels, and associated equip- Blooms, and Forgings5
ment.
2.2 Other Standard:
NOTE 1—Designations have been changed as follows: ASME Boiler and Pressure Vessel Code, Section IX, Weld-
Current Formerly ing Qualifications7
Grade 1 Class 1
Grade 2 Class 2
Grade 3 Class 3 3. Ordering Information and General Requirements
Grade 4 Class 4 3.1 In addition to the ordering information required by
1.2 Supplementary requirements are provided for use when Specification A 788, the purchaser shall include with the
additional testing or inspection is desired. These shall apply inquiry and order a detailed drawing, sketch, or written
only when specified individually by the purchaser in the order. description of the forging.
1.3 The values stated in either inch-pound units or SI 3.2 Material supplied to this specification shall conform to
(metric) units are to be regarded separately as the standard. the requirements of Specification A 788, which outlines addi-
Within the text and tables, the SI units are shown in brackets. tional ordering information, manufacturing requirements, test-
The values stated in each system are not exact equivalents; ing and retesting methods and procedures, marking, certifica-
therefore, each system must be used independently of the other. tion, product analysis variations, and additional supplementary
Combining values from the two systems may result in noncon- requirements.
formance with the specification. 3.3 If the requirements of this specification are in conflict
1.4 Unless the order specifies the applicable “M” specifica- with the requirements of Specification A 788, the requirements
tion designation, the material shall be furnished to the inch- of this specification shall prevail.
pound units.
4. Materials and Manufacture
2. Referenced Documents 4.1 The steel shall be made in accordance with the Melting
2.1 ASTM Standards: Process Section of Specification A 788. A sufficient discard
A 275/A 275M Test Method for Magnetic Particle Exami- shall be made to secure freedom from injurious pipe and undue
nation of Steel Forgings3 segregation.
A 370 Test Methods and Definitions for Mechanical Testing 4.2 The material shall be forged as close as practical to the
of Steel Products4 specified shape and size.
A 788 Specification for Steel Forgings, General Require- 4.3 The finished product shall be a hot-worked forging as
ments3 defined by Specification A 788.
E 112 Test Methods for Determining the Average Grain
Size5 5. Machining
5.1 Surfaces shall be machined as designated by the pur-
chaser. Unmachined surfaces shall be sufficiently free of scale
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to permit inspection.
This specification is under the jurisdiction of ASTM Committee A-1 on Steel,
5.2 Machining may be performed either prior to or after heat
Stainless Steel, and Related Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets. treatment at the option of the manufacturer unless specified in
Current edition approved Sept. 10, 1999. Published November 1999. Originally accordance with Supplementary Requirement S1.
published as A 266 – 43T. Last previous edition A 266/A 266M–96.
2
For ASME Boiler and Pressure Vessel Code applications, see related Specifi-
cation SA–266/ SA–266M in Section II of that code.
3 6
Annual Book of ASTM Standards, Vol 01.05. Annual Book of ASTM Standards, Vol 03.03.
4 7
Annual Book of ASTM Standards, Vol 01.03. Available from the American Society of Mechanical Engineers, 345 East 47th
5
Annual Book of ASTM Standards, Vol 03.01. St., New York, NY 10017.

Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.

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 A 266/A 266M
6. Heat Treatment TABLE 2 Tensile Requirements

6.1 After forging and before reheating for heat treatment, Grade 1 Grades Grade 3
2 and 4
the forgings shall be cooled in such a manner as to prevent
Tensile strength, min, ksi 60–85 70–95 75–100
injury and to accomplish transformation. [MPa] [415–585] [485–655] [515–690]
6.2 All forgings shall be annealed, normalized, or normal- Yield strength (0.2 % offset), 30 36 37.5
ized and tempered, but alternatively may be liquid quenched min, ksi [MPa] [205] [250] [260]
Elongation in 2 in. or 50 23 20 19
and tempered when mutually agreed upon between the manu- mm, min, %
facturer and the purchaser. When tempering is performed, it Reduction of area, min, % 38 33 30
shall be at a subcritical temperature, but no less than 1100°F
[595°C].
6.3 A multiple stage austenitizing procedure may be used the longitudinal axis of the specimens shall be located midway
whereby the forging is first fully austenitized and liquid between the center and outer surfaces of the wall. When
quenched, followed by reheating within the intercritical tem- separately forged test blocks are employed as defined in 8.1.3,
perature range to partially reaustenitize, and again liquid the tension test specimens shall be taken from a location that
quenched. On completion of the austenitizing/quenching represents the midwall of the heaviest section of the production
cycles, tempering at a temperature between 1100°F [595°C] forgings. When specimens are required from opposite ends,
and the lower critical temperature shall follow. they shall be taken from the diagonal corners of an axial plane.
NOTE 2—Although liquid quenching from the austenitizing tempera- 8.1.2 Except as specified herein, tests for acceptance shall
tures is more effective in enhancing impact properties, air cooling from the be made after heat treatment has been completed. When the
austenitizing temperatures is also beneficial and may be used instead of ends of the cylindrical forgings are closed in by reforging, the
the normalizing procedure in 6.2. cylindrical forgings may be annealed, normalized, or normal-
ized and tempered and tested prior to reforging. After reforg-
7. Chemical Composition ing, the entire forging shall be reheat-treated in the same
7.1 Heat Analysis—The heat analysis obtained from sam- manner and at the same temperature range as employed when
pling in accordance with Specification A 788 shall comply with the forging was heat-treated prior to certification testing.
Table 1 except that the additional features of Supplementary 8.1.3 When mutually agreed upon between manufacturer
Requirements S11 and S12 shall also apply as individually and purchaser, test specimens may be machined from a
specified in the ordering information. specially forged block suitably worked and heat treated with
7.2 Product Analysis—The purchaser may use the product the production forgings. Such a special block shall be obtained
analysis provision of Specification A 788 to obtain a product from an ingot, slab, or billet from the same heat used to make
analysis from a forging representing each heat or multiple heat. the forgings it represents. This block shall receive essentially
the same type of hot working and forging reduction as the
8. Mechanical Properties production forgings; however, a longitudinally forged bar with
8.1 General Requirements—Except when otherwise speci- dimensions not less than T by T by 3T may be used to represent
fied in accordance with Supplementary Requirement S2, the a ring forging. The dimension T shall be representative of the
material shall conform to the requirements for mechanical heaviest effective cross section of the forging. For quenched
properties prescribed in Table 2 when tested in accordance with and tempered forgings for which tests are required at both ends
the latest issue of Test Methods and Definitions A 370. The by 8.2.2.3 and 8.2.2.4, separately forged test blocks are not
largest obtainable tension test specimen as specified in Test allowed.
Methods and Definitions A 370 shall be used.
NOTE 3—In using separately forged test blocks, attention is drawn to
8.1.1 Except when otherwise specified in accordance with the effect of mass differences between the production forgings and the test
Supplementary Requirement S2, the longitudinal axis of the blocks.
specimens shall be parallel to the direction of major working of
8.2 Specific Requirements—The number and location of
the forging. For upset-disc forgings, the longitudinal axis of the
tests are based on forging length, weight, and heat treatment,
test specimen shall be in the tangential direction.
and shall be as prescribed below. The length and weight to be
8.1.1.1 The longitudinal axis of the specimen shall be
used for this purpose shall be the shipped length and weight of
located midway between the parallel surfaces of the test
forgings produced individually or the aggregate shipped length
extension if added to the periphery of disks or midway between
and weight of all pieces cut from a multiple forging.
the center and surface of solid forgings. For hollow forgings,
8.2.1 Annealed, Normalized, or Normalized and Tempered
Steel Forgings:
TABLE 1 Chemical Requirements 8.2.1.1 For forgings weighing 5000 lb [2250 kg] or less at
Composition, % the time of heat treatment, one tension test shall be taken from
Grades 1 and 2 Grade 3 Grade 4 one forging per heat in each heat–treatment charge. When heat
Carbon, max 0.30 0.35 0.30 treatment is performed in continuous-type furnaces with suit-
Manganese 0.40–1.05 0.80–1.35 0.80–1.35 able temperature controls and equipped with recording pyrom-
Phosphorus, max 0.025 0.025 0.025 eters so that complete heat-treatment records are available, a
Sulfur, max 0.025 0.025 0.025
Silicon 0.15–0.35 0.15–0.35 0.15–0.35 tempering charge may be considered as any continuous run not
exceeding an 8-h period.

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 A 266/A 266M
8.2.1.2 For forgings and forged bars weighing over 5000 lb exceeds 12 ft [3.7 m], then one specimen shall be taken from
[2250 kg] at the time of heat treatment, one tension test shall be each end of the forging.
taken from each forging.
8.2.2 Quenched and Tempered Forgings: 9. Repair Welding
8.2.2.1 For quenched and tempered forgings weighing 5000 9.1 Repair welding of forgings is permissible only at the
lb [2250 kg] or less at the time of heat treatment, but not option of the purchaser. If repair welding is performed, welders
exceeding 12 ft [3.7 m] in length, one tension test shall be and weld procedures shall be qualified in accordance with
taken from one forging per heat in each heat–treatment charge. Section IX of the ASME Boiler and Pressure Vessel Code.
When heat treatment is performed in continuous-type furnaces
with suitable temperature controls and equipped with recording 10. Certification
pyrometers so that complete heat-treatment records are avail-
10.1 In addition to the mandatory certification requirements
able, a tempering charge may be considered as any continuous
of Specification A 788, the heat treatment cycle data shall be
run not exceeding an 8-h period.
included.
8.2.2.2 For quenched and tempered forgings and forged bars
weighing over 5000 lb [2250 kg] to 10 000 lb [4500 kg] at the
11. Product Marking
time of heat treatment, but not exceeding 12 ft [3.7 m] in
length, one tension test shall be taken from each forging. 11.1 Each forging shall be identified in accordance with the
8.2.2.3 For quenched and tempered forgings and forged bars Marking Section of Specification A 788. In addition, the
that exceed 12 ft [3.7 m] in length, one tension test shall be forging shall be marked following the grade designation by the
taken from each end of each forging. letter “A” for annealed, “N” for normalized, “NT” for normal-
8.2.2.4 For quenched and tempered forgings and forged bars ized and tempered, and “S” for liquid quenched and tempered,
weighing more than 10 000 lb [4500 kg] at the time of heat as applicable.
treatment, two tension test specimens shall be taken from each
forging. These shall be offset 180° from each other except that 12. Keywords
if the length of the forging, excluding test prolongations, 12.1 pressure vessel service; steel forgings—carbon

SUPPLEMENTARY REQUIREMENTS

One or more of the following supplementary requirements shall apply only when specified by the
purchaser in the inquiry, contract, or order. Details of these supplementary requirements shall be
agreed upon between the manufacturer and the purchaser.

S1. Rough Turning and Boring S5. Liquid Penetrant Examination

S1.1 The position of the rough turning and boring in the S5.1 After forgings have been heat treated by liquid quench-
sequence of manufacturing operations shall be as specified by ing and tempering, all accessible surfaces shall be inspected for
the purchaser. quench cracks by the liquid penetrant method in accordance
with Test Method E 165 as an alternative to magnetic particle
S2. Alternative Tension Test Orientation examination.
S2.1 In lieu of the requirements of Section 8, the longitu-
dinal axis of the test specimens shall be transverse to the S6. Macroetch Test
direction of major working of the forging. The results shall S6.1 A sample forging shall be sectioned and etched to
conform with requirements of Table 2, with the exception of show flow lines and internal imperfections. The test shall be
the ductility limits that shall be as follows: conducted in accordance with Method E 381. Details of the test
Grade 1 2 and 4 3 shall be agreed upon between the manufacturer and the
Elongation in 2 in. [50 mm], min, % 20 19 18 purchaser.
Reduction of area, min, % 30 25 25

S3. Hydrostatic Test S7. Product Analysis

S3.1 A hydrostatic pressure test shall be applied. The details S7.1 A product analysis in accordance with Section 7 shall
of the test, including its position in the sequence of manufac- be made from one randomly selected forging representing each
turing operations, shall be specified. size and shape of forging on the order. If the analysis fails to
comply, each forging shall be checked or the lot rejected. All
S4. Magnetic Particle Examination results shall be reported to the purchaser.
S4.1 All accessible surfaces of the finished forging shall be
examined by a magnetic particle method. The method shall be S8. Specimen Location on Forged Hubs
in accordance with Test Method A 275/A 275 M. Acceptance S8.1 Forged hubs to be butt-welded to shells shall be forged
limits shall be as agreed upon between the manufacturer and in such a manner as to provide in the hub the full minimum
the purchaser. tensile strength and elongation specified for the material, in a

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 A 266/A 266M
direction parallel to the axis of the vessel. A tension specimen S13. Impact Tests
(subsize if necessary) shall be taken in this direction and as S13.1 Charpy impact tests shall be made. The number and
close to the finished hub outside diameter as practical. location of the tests, minimum properties, and test temperatures
shall be specified.
S9. Hardness
S13.2 The specimens shall be machined and tested in
S9.1 The purchaser may check the Brinell hardness of the accordance with Test Methods and Definitions A 370.
forging at any location on the surface of the forging, and the
hardness shall be within the following limits: S13.3 Retests may be conducted in accordance with Section
10 of Specification A 788.
Grade Brinell Hardness Limits
1 121 to 170
2 and 4 137 to 197 S14. Individual Forging
3 156 to 207
S14.1 Forgings, whether identical or not, shall be pro-duced
S10. Grain Size individually. They shall not be forged in multiples and sepa-
S10.1 The austenitic grain size of the steel shall be 1 to 5 as rated prior to or after heat treatment.
determined using Test Methods E 112. S14.2 The shape and size of individual forgings shall be
agreed upon between the manufacturer and the purchaser by
S11. Restriction on Residual Elements (Applicable to means of a forging drawing or the purchase order.
Heat Analysis)
S11.1 Nickel, chromium, and molybdenum shall be deter- S15. Carbon Equivalancy
mined and shall not exceed the following limits: S15.1 The heat analysis including the residual element
restrictions of S1 in Specification A 788 shall be limited such
Nickel 0.25 % max
that the carbon equivalent shall not exceed 0.45 for Grade 1 or
Chromium 0.20 % max
Molybdenum 0.08 % max 0.50 for Grade 2 or 4 when calculated in accordance with the
following formula:
S12. Restriction on Carbon (Applicable to Grade I) % Mn % Cr 1 % Mo 1 % V % Ni 1 % Cu
S12.1 The carbon content shall be 0.30 % max. CE 5 % C 1 6 1 5 1 15

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