ASTM A668/A668M-04(2009)
(Specification)Standard Specification for Steel Forgings, Carbon and Alloy, for General Industrial Use
Standard Specification for Steel Forgings, Carbon and Alloy, for General Industrial Use
ABSTRACT
This specification deals with the standard requirements for untreated and heat-treated carbon and alloy steel forgings for general industrial use. This specification covers six classes of carbon steels (Class A to F) and seven classes of alloy steels (Class G, H, and J to N). Materials shall be forged by hot mechanical work. Except for Class A, all forgings shall be heat treated, depending on class, by the following techniques: annealed, or normalized, or normalized and tempered (Classes B, C, D, and G); normalized and tempered, or double-normalized and tempered (Class E); quenched and tempered, or normalized, quenched, and tempered (Classes F); normalized and tempered (Class H); normalized and tempered, or normalized, quenched, and tempered (Class J); and normalized, quenched, and tempered (Classes K, L, M, and N). Steel specimens shall undergo heat and product analyses, and shall conform to required chemical compositions for manganese, phosphorus, and sulfur. Steel forgings shall also be tested on their conformance to the following tensile requirements: tensile strength, yield point, yield strength, elongation, reduction of area, and Brinell hardness.
SCOPE
1.1 This specification covers untreated and heat-treated carbon and alloy steel forgings for general industrial use. Other ASTM specifications for forgings are available for specific applications such as pressure vessels, railroad use, turbine generators, gearing, and others involving special temperature requirements.
1.2 Hot-rolled or cold finished bars are not within the scope of this specification.
1.3 Six classes of carbon steel and seven classes of alloy steel forgings are listed (see Section 7) , which indicates their required heat treatments, as well as mechanical properties.
1.4 Provision, with the suffix H for certification and marking, for the supply of forgings after hardness testing only.
1.5 Supplementary requirements, including those in Specification A788/A788M, of an optional nature are provided. These shall apply only when specified by the purchaser.
1.6 Appendix X1 lists the current classes corresponding to the various classes of Specifications A235, A237, and A243, which have been superseded by this specification.
1.7 The values stated in either inch-pound units or SI units are to be regarded separately as the standard; within the text and tables, the SI units are shown in brackets. The values stated in each system are not exactly equivalent; therefore; each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.
1.8 Unless the order specifies the applicable "M" specification, the forgings shall be furnished to the inch-pound units
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Designation:A668/A668M −04(Reapproved 2009) American Association State
Highway and Transportation Officials Standard
AASHTO No.: M 102
Standard Specification for
Steel Forgings, Carbon and Alloy, for General Industrial
Use
This standard is issued under the fixed designationA668/A668M; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This specification covers untreated and heat-treated
carbon and alloy steel forgings for general industrial use. Other A275/A275M Practice for Magnetic Particle Examination of
Steel Forgings
ASTM specifications for forgings are available for specific
applications such as pressure vessels, railroad use, turbine A370 Test Methods and Definitions for Mechanical Testing
of Steel Products
generators, gearing, and others involving special temperature
requirements. A388/A388M Practice for Ultrasonic Examination of Steel
Forgings
1.2 Hot-rolled or cold finished bars are not within the scope
A788/A788M Specification for Steel Forgings, General Re-
of this specification.
quirements
1.3 Six classes of carbon steel and seven classes of alloy
E381 Method of Macroetch Testing Steel Bars, Billets,
steel forgings are listed (see Section 7) , which indicates their
Blooms, and Forgings
required heat treatments, as well as mechanical properties.
3. Terminology
1.4 Provision, with the suffix H for certification and
marking, for the supply of forgings after hardness testing only.
3.1 The terminology section of Specification A788/A788M is
applicable to this specification.
1.5 Supplementary requirements, including those in Speci-
fication A788/A788M, of an optional nature are provided.
3.2 Definitions of Terms Specific to This Standard:
These shall apply only when specified by the purchaser.
3.2.1 hollow cylindrical forging—a forging whose length,
as measured on its longitudinal axis is more than its diameter,
1.6 Appendix X1 lists the current classes corresponding to
shall be considered as a hollow cylinder within the scope of
the various classes of Specifications A235, A237, and A243,
this specification if it has been lengthened by extrusion or
which have been superseded by this specification.
forged in a manner similar to that of a ring, namely, expanded
1.7 The values stated in either inch-pound units or SI units
in diameter on a mandrel.
are to be regarded separately as the standard; within the text
3.2.2 ring-shaped or disk-shaped forging—a forging whose
andtables,theSIunitsareshowninbrackets.Thevaluesstated
length, as measured on its longitudinal axis, is less than its
in each system are not exactly equivalent; therefore; each
diameter or main transverse dimension is considered a ring or
system must be used independently of the other. Combining
disk within the meaning of this specification.
values from the two systems may result in nonconformance
with the specification.
4. Ordering Information and General Requirements
1.8 Unless the order specifies the applicable "M"
4.1 Material supplied to this specification shall conform to
specification, the forgings shall be furnished to the inch-pound
the requirements of Specification A788/A788M which outlines
units
additional ordering information, manufacturing requirements,
testing and retesting methods and procedures, marking,
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2009. Published March 2010. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1972. Last previous edition approved in 2004 as A668/A668M – 04. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/A0668_A0668M-04R09. 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
A668/A668M−04(Reapproved 2009)
certification, product analysis variations and additional supple-
mentary requirements.
A668/A668M−04 (2009)
4.1.1 If the requirements of this specification are in conflict supplied, the product analysis can be used only to confirm the
with the requirements of Specification A788/A788M, the type of steel supplied.
requirements of this specification shall prevail.
7. Mechanical Properties
4.2 When this specification is to be applied to an inquiry,
contract, or order, the purchaser should furnish the following
7.1 Tensile Requirements:
information:
7.1.1 The material shall conform to the tensile properties
4.2.1 The ordering information required by Specification
prescribed in Table 2.
A788/A788M.
7.1.2 Size Classification—The dimensions of the forging at
4.2.2 The class of forging desired as listed in Section Table
time of heat treatment determine the size classification (see
1,
Table 2):
4.2.3 Location(s) of areas of significant loading if test
7.1.2.1 Solid Forgings—Either the as forged or rough ma-
specimens are to be located in accordance with 7.1.4.5.
chined diameter or thickness of solid forgings, disregarding
4.2.4 The options which may be selected as found in 5.4.2,
large ends, collars, flanges, and journals, at time of heat
7.6.3, and 7.7, and
treatment shall determine the size classification.
4.2.5 Any applicable supplementary requirements.
7.1.2.2 Ring or Hollow Cylinder Forging— The size classi-
fication shall be determined by its wall thickness or width,
5. Materials and Manufacture
whichever is the smaller dimension of either the as forged or
5.1 Discard—Sufficient discard shall be made from each
rough machined forging at time of heat treatment.
ingot to secure freedom from piping and undue segregation.
7.1.3 Number of Tests—Unless the purchaser specifies that
5.2 Forging Process
forgingsshallbefurnishedinaccordancewiththerequirements
5.2.1 The forging shall be brought as close as practical to
of 7.3, the number of tension tests performed shall be as
finished shape and size by hot mechanical work.
follows:
5.2.2 Supplementary requirements S2, S14, and S15 may be
7.1.3.1 For all classes of heat-treated forgings with rough
specified by the purchaser to satisfy concerns about the utility
machined weights less than 5000 lb [2250 kg] each, one test
of the proposed forging.
shall be made from each size classification represented in each
heatineachannealingornormalizingcharge,orfromeachsize
5.3 Heat Treatment:
classification in each heat in each normalizing or quenching
5.3.1 All forgings, other than ClassA, shall be heat treated.
charge represented in each tempering charge. For untreated
See Section 7.
forgings (Class A) weighing less than 5000 lb [2250 kg] each,
5.3.2 Where options exist within a class, the choice of heat
one test from each heat shall be made.
treatment shall be left to the discretion of the manufacturer,
unless the purchaser specifies one of the available options. 7.1.3.2 On all classes, for forgings with rough machined
weights of 5000 lb [2250 kg] or more, at least one test from
6. Chemical Composition
each forging shall be made.
7.1.3.3 On all classes, for forgings with rough machined
6.1 Thesteelshallconformtotherequirementsforchemical
weights of 7000 lb [3200 kg] or more, two tests will be taken:
composition prescribed in Table 1.
on ring and disk forgings 180 ° apart; on shafts and long
6.2 The choice of chemical composition is left to the
hollow cylinders (over 80 in. [2.0 m] in length excluding test
discretion of the manufacturer, unless otherwise specified by
material), one from each end and offset 180 °. Shafts and
the purchaser. See Appendix X2.
cylinder forgings 80 in. [2.0 m] or less in length (excluding test
6.3 Heat Analysis:
material) may have both tests located at one end 180 ° apart.
6.3.1 An analysis of each heat shall be made by the
7.1.3.4 When forgings are made in multiple as a single
manufacturer.
forging, that is, forged as one piece and divided after heat
6.4 Product Analysis—An analysis may be made by the treatment, the multiple forging shall be considered as one
purchaseraccordingtotherequirementsofSpecificationA788/ forging, and the number of tests required shall be as designated
in 7.1.3.1, 7.1.3.2, and 7.1.3.3.
A788M. If a standard grade has been used to manufacture the
forging the permissible variations in composition of Specifi-
7.1.4 Prolongations:
cation A788/A788M shall apply. If a non-standard grade of
7.1.4.1 A sufficient number of the forgings shall have
steel has been used, and composition limits have not been
prolongations for extracting specimens for testing. Locations
of test specimens for various types of forgings shall be as
shown in Fig. 1.
TABLE 1 Chemical Requirements
7.1.4.2 The nominal or principal outside rough machine
Elements Composition, max, % diameter or thickness of the forgings, disregarding large ends,
Classes A to F Classes G to N collars, flanges, and journals shall determine the size of the
and AH to FH and GH to NH
prolongations for test specimens; however, the prolongations
Manganese 1.35 .
on annealed, normalized, or normalized and tempered shafts
Phosphorus 0.050 0.040
may be extensions of the small diameter end of the shaft, as
Sulfur 0.050 0.040
shown in Fig. 1.
A668/A668M−04 (2009)
TABLE 2 Tensile Requirements
Yield Point, Yield Elonga-
Reduc-
Strength 0.2 % tionin2
Size, in. [mm] Tensile Strength, min
tion of Brinell
Class Offset, min in. or
Area, Hardness
50 mm,
min, %
Over Not Over psi MPa psi MPa
min, %
Carbon Steel
A (AH) (Untreated) . 20 [500] 47 000 325 . . . . 183 max
B (BH) (Annealed, or normalized, or . 20 [500] 60 000 415 30 000 205 24 36 120–174
normalized and tempered)
C (CH) (Annealed, or normalized, or . 12 [300] 66 000 455 33 000 230 23 36 137–183
normalized and tempered) 12 [300] 20 [500] 66 000 455 33 000 230 22 34 137–183
D (DH) (Normalized, annealed, or normalized . 8 [200] 75 000 515 37 500 260 24 40 149–207
and tempered) 8 [200] 12 [300] 75 000 515 37 500 260 22 35 149–207
12 [300] 20 [500] 75 000 515 37 500 260 20 32 149–207
20 [500] 75 000 515 37 500 260 19 30 149–207
E (EH) (Normalized and tempered or . 8 [200] 85 000 585 44 000 305 25 40 174–217
double-normalized and tempered) 8 [200] 12 [300] 83 000 570 43 000 295 23 37 174–217
12 [300] 20 [500] 83 000 570 43 000 295 22 35 174–217
F (FH) (Quenched and tempered, or . 4 [100] 90 000 620 55 000 380 20 39 187–235
normalized, quenched and tempered) 4 [100] 7 [175] 85 000 585 50 000 345 20 39 174–217
7 [175] 10 [254] 85 000 585 50 000 345 19 37 174–217
10 [250] 20 [500] 82 000 565 48 000 330 19 36 174–217
Alloy Steel
G (GH) (Annealed, or normalized, or . 12 [300] 80 000 550 50 000 345 24 40 163–207
normalized and tempered) 12 [300] 20 [500] 80 000 550 50 000 345 22 38 163–207
H (HH) (Normalized and tempered) . 7 [175] 90 000 620 60 000 415 22 44 187–235
7 [175] 10 [250] 90 000 620 58 000 400 21 42 187–235
10 [250] 20 [500] 90 000 620 58 000 400 18 40 187–235
J (JH) (Normalized and tempered, or . 7 [175] 95 000 655 70 000 485 20 50 197–255
normalized, quenched, and tempered) 7 [175] 10 [250] 90 000 620 65 000 450 20 50 187–235
10 [250] 20 [500] 90 000 620 65 000 450 18 48 207–255
K (KH) (Normalized, quenched, and tempered) . 7 [178] 105 000 725 80 000 550 20 50 212–269
7 [175] 10 [250] 100 000 690 75 000 515 19 50 207–269
10 [250] 20 [500] 100 000 690 75 000 515 18 48 207–269
L (LH) (Normalized, quenched, and tempered) . 4 [100] 125 000 860 105 000 725 16 50 255–321
4 [100] 7 [175] 115 000 795 95 000 655 16 45 235–302
7 [175] 10 [250] 110 000 760 85 000 585 16 45 223–293
10 [250] 20 [500] 110 000 760 85 000 585 14 40 223–293
M (MH) (Normalized, quenched, . 4 [100] 145 000 1000 120 000 825 15 45 293–352
and tempered) 4 [100] 7 [175] 140 000 965 115 000 790 14 40 285–341
7 [178] 10 [254] 135 000 930 110 000 758 13 40 269–331
10 [250] 20 [500] 135 000 930 110 000 758 12 38 269–341
N (NH) (Normalized, quenched, and tempered) . 4 [100] 170 000 1175 140 000 965 13 40 331–401
4 [100] 7 [175] 165 000 1140 135 000 930 12 35 331–401
7 [175] 10 [250] 160 000 1100 130 000 900 11 35 321–388
10 [250] 20 [500] 160 000 1100 130 000 900 11 35 321–402
7.1.4.3 For quenched forgings in Classes F, J, K, L, M, and (3) On disk forgings (see Fig. 1(c)) (with prolongation on
1 1
N, the prolongations shall be sufficiently long so that the center
OD), at midthickness and from the OD 3 ⁄2 in. [90 mm] or ⁄2
of the gage length (for longitudinal specimens) or axis (for
the thickness, whichever is less.
tangential specimens) of the tension test specimen shall be at
(4) On disk forgings (see Fig. 1(c)) (with prolongation on
the following locations:
1 1
the width or thickness) 3 ⁄2 in. [90 mm] or ⁄2 the thickness,
(1) On solid round forgings, bars, or billets (see Fig. 1 (a)),
whichever is less, from any heat treated surface.
1 1
at midradius and from the end, 3 ⁄2 in. [90 mm] or ⁄2 the
(5) On ring forgings (see Fig. 1(d)) (with prolongation on
diameter, whichever is less.
width), at midwall and from the ring face 3 ⁄2 in. [90 mm] or
(2) On solid rectangular forgings, bars, or billets, at ⁄4 the
1 1 ⁄2 the wall thickness, whichever is less.
thickness and width and from the end, 3 ⁄2 in. [90 mm] or ⁄2
the thickness, whichever is less.
A668/A668M−04 (2009)
FIG. 1Locations of Test Specimens for Various Types of Forgings
(6) On ring forgings (see Fig. 1(d)) (with prolongation on sents; or (2) obtain the test specimen from the trepanned
1 1
the OD), at midwidth and from the OD 3 ⁄2 in. [90 mm] or ⁄2 material of transverse or radial holes, provided depth is equal
the width, whichever is less. to or greater than the minimum depth required by 7.1.4.3.
7.1.4.4 Inplaceofprolongs,themanufacturermay:(1)elect 7.1.4.5 With prior purchaser approval, test specimens may
to submit an extra forging(s) to represent each test lot; in this be taken at a depth (t) corresponding to the distance from the
event, the representative forging must be made from the same area of significant stress to the nearest heat treated surface and
heat of steel, have received the same reduction and type of hot at least twice this distance (2t) from
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