A 730 – 93 (Reapproved 1999) Designation A 730 – 93 (Reapproved 1999) Standard Specification for Forgings, Carbon and Alloy Steel, for Railway Use1 This standard is issued under the fixed designation[.]
Trang 1Standard Specification for
This standard is issued under the fixed designation A 730; 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.
1 Scope
1.1 This specification covers eight grades of untreated and
heat-treated carbon steel forgings and six grades of heat-treated
alloy steel forgings for railway use
N OTE 1—It is recommended, when semi-finished steel is desired to
process these forgings, that the latest issue of ASTM Specification A 711,
for Carbon and Alloy Steel Blooms, Billets, and Slabs for Forging, 2 be
used This will enable the forger to select semi-finished material of such
chemistry as he desires.
N OTE 2—Railway axles are covered by Specification A 21.
1.2 The grades of carbon steel forgings and the purposes for
which they are frequently used are as follows, the choice
depending on design and stress or service to be imposed:
1.2.1 Grade A is untreated and is mostly used for drop
forgings and parts of minor importance, and those which are to
be case hardened
1.2.2 Grade B is untreated and is used for a general group
of miscellaneous ordinary forgings where heat treatment is not
deemed necessary
1.2.3 Grade C is annealed, normalized, or normalized and
tempered
1.2.4 Grade D is annealed, normalized, or normalized and
tempered
1.2.5 Grade E is normalized and tempered.
1.2.6 Grade F is double normalized and tempered.
1.2.7 Grade G is quenched and tempered.
1.2.8 Grade H is normalized, quenched, and tempered.
1.2.9 Grades E, F, G, and H forgings are used in high-duty
service on locomotives, cars, and other equipment
1.3 The grades of alloy steel forgings are as follows:
1.3.1 Grades I, J, and K are normalized and tempered.
1.3.2 Grades L, M, and N are normalized, quenched, and
tempered, and are used in heavy-duty service on locomotives,
cars, and special equipment
N OTE 3—The forgings described above were formerly designated as
follows:
Current Grade Former Designation and Grade
1.4 Supplementary Requirements (Sections S1 to S5) of an optional nature are provided These shall apply only when specified by the purchaser
1.5 The values stated in inch-pound units are to be regarded
as the standard
2 Referenced Documents
2.1 ASTM Standards:
A 21 Specification for Carbon Steel Axles, Non-Heat-Treated and Heat-Non-Heat-Treated, for Railway Use2
A 370 Test Methods and Definitions for Mechanical Testing
of Steel Products3
A 711 Specification for Steel Forging Stock4
E 112 Test Methods for Determining the Average Grain Size5
E 381 Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings5
3 Ordering Information
3.1 The purchaser shall specify in the inquiry, contract, and order the grade of steel desired, and any restrictive modifica-tions of this specification
3.2 Supplementary requirements are provided and shall apply only when specified in the purchase order
4 Manufacture
4.1 Melting Process—The steel shall be made by one or
more of the following processes: open-hearth, basic-oxygen, or electric-furnace
1
This specification is under the jurisdiction of ASTM Committee A-1 on Steel,
Stainless Steel, and Related Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets.
Current edition approved Dec 15, 1993 Published February 1994 Originally
published as A 730–76 to replace A 236 and A 238 Last previous edition
A 730–81(1988).
2Annual Book of ASTM Standards, Vol 01.04.
3Annual Book of ASTM Standards, Vol 01.03.
4
Annual Book of ASTM Standards, Vol 01.05.
5Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
Trang 24.2 Discard—Sufficient discard shall be made to assure
freedom from piping and undue segregation
4.3 Forging Practice—The forgings may be made direct
from the ingot or from blooms The total reduction from ingot
or strand cast bloom to forging shall not be less than 3 to 1,
unless otherwise specified
4.4 Cooling and Heating:
4.4.1 After carbon steel blooms are produced, they shall be
allowed to cool uniformly and shall not be subject to contact
with water or drafts
4.4.2 After alloy steel blooms are produced, they shall be
cooled in closed containers, hoods, or furnaces
4.4.3 Blooms shall be reheated for forging in a manner that
will prevent internal bursts and overheating
4.4.4 Forgings (Grades C through N) shall be slow cooled in
closed containers, covered conveyors, or hoods If forgings
(Grades C through N) are heat treated directly from forging,
they shall be slow cooled following the final heat treatment
4.4.5 Forgings (Grades C through N) that are heat treated
directly from forging (1) shall be cooled below the
transfor-mation temperature or to approximately 1000°F (538°C)
be-fore any reheating operation, and (2) must not be permitted to
cool below 500°F (260°C) without slow cooling as defined in
4.4.4
N OTE 4—As the temperature of the forgings approaches the minimum
of 500°F (260°C) a supplemental heat source may be necessary to assure
an effective slow cooling cycle.
4.4.6 When properly vacuum degassed steel is used, the
slow cooling requirements of 4.4.2, 4.4.4 and item (2) of 4.4.5
may be omitted, but forging blooms must then be pile cooled
4.5 Boring:
4.5.1 Boring, if specified under Supplementary
Require-ment S5, shall be performed before normalizing or quenching
in the case of normalized and tempered or quenched and
tempered forgings, and before either normalizing or quenching,
in the case of normalized, quenched, and tempered forgings
4.5.2 For quenched and tempered forgings or normalized,
quenched and tempered forgings it is recommended, but not
mandatory, that all forgings over 7 in (178 mm) in diameter be
bored
4.5.3 For carbon steel no solid forgings over 10 in (254
mm) in diameter and no forgings over 8 in (203 mm) in wall
thickness shall be liquid quenched under this specification
4.5.4 In bored forgings, the diameter of the hole shall be a
matter of agreement between the manufacturer and the
pur-chaser
4.6 Heat Treatment:
4.6.1 Forgings for heat treatment shall be reheated gradually and uniformly to the proper temperature to refine the grain and shall be held at this temperature for a sufficient time to effect the desired change
4.6.2 Annealing—After heating to a suitable temperature
the forgings shall be allowed to cool slowly and uniformly A furnace charge thus treated is termed an annealing charge
4.6.3 Normalizing—After heating to a suitable temperature,
the forgings shall be withdrawn from the furnace and allowed
to cool uniformly in air A furnace charge thus treated is termed
a normalizing charge Cooling may be accelerated by increased air circulation, which must be controlled to provide reasonably uniform cooling
4.6.4 Double Normalizing—The procedure shall consist of
two separate heat treatments The second treatment shall be performed at a lower temperature than the first A furnace charge thus treated is termed a double-normalizing charge Cooling may be accelerated by increased air circulation, which must be controlled to provide reasonably uniform cooling
4.6.5 Quenching—After heating to a suitable temperature,
the forgings shall be quenched in a suitable medium under reasonably uniform conditions A furnace charge thus treated is termed a “quenching charge.”
4.6.6 Tempering—Forgings shall be reheated gradually to,
and held at, a suitable temperature below the critical range and shall then be allowed to cool under suitable conditions A furnace charge thus treated is termed a “tempering charge.” 4.6.7 Heat treatment may be performed in either batch-type furnaces or continuous furnaces
4.7 Straightening:
4.7.1 Straightening of forgings shall be done before machin-ing and in such a manner as to leave the surface free of injurious scars
4.7.2 Straightening preferably shall be performed at a tem-perature no lower than 950°F (510°C) Straightening per-formed at temperatures lower than 950°F shall be followed by stress relieving or applicable heat treatment
5 Chemical Requirements
5.1 Composition:
5.1.1 Carbon steel (Grades A through H) shall conform to the requirements for chemical composition prescribed in Table 1
5.1.2 Alloy steel (Grades I through N) shall conform to the following requirements for chemical composition:
Phosphorus 0.045 max Sulfur 0.050 max
TABLE 1 Chemical Requirements for Carbon Steels
Grade A Grade B Grades C, D, and E Grade F Carbon 0.15 max 0.15–0.25 0.40–0.55 0.45–0.59
Manganese 0.30–0.60 0.30–0.60 0.60–0.90 0.60–0.90 0.60–0.90
Trang 3By agreement between purchaser and manufacturer, analysis
may be required and limits established for elements not
specified above
5.2 Cast or Heat Analysis:
5.2.1 An analysis of each cast or heat of carbon steel shall
be made by the manufacturer to determine the percentages of
carbon and the elements prescribed in Table 1 The chemical
composition thus determined shall be reported to the purchaser
or his representative and shall conform to the requirements
prescribed in Table 1
5.2.2 An analysis of each cast or heat of alloy steel shall be
made by the manufacturer to determine the percentage of
carbon, manganese, phosphorus, sulfur, and silicon; also the
alloying elements agreed upon in accordance with 5.1.2 The
chemical composition thus determined shall be reported to the
purchaser or his representative and shall conform to the
requirements specified and agreed upon in 5.1.2
5.3 Product Analysis:
5.3.1 An analysis may be made by the purchaser from a
carbon steel forging representing each heat The chemical
composition thus determined shall conform to the requirements
in Table 1, subject to the tolerances shown in Table 2
5.3.2 An analysis may be made by the purchaser from an
alloy steel forging representing each heat The chemical
composition thus determined shall conform to the requirements
of 5.1.2 subject to tolerances shown in Table 3
5.3.3 Samples for analysis may be taken from the forging or
from a full-size prolongation, at any point midway between the
center and surface when solid, or midway between the inner
and outer surfaces of the wall when bored If drillings are
taken, they shall be obtained by using a 5⁄8 -in (16-mm)
diameter drill, or turnings may be taken from the test specimen
6 Physical Requirements
6.1 Tensile Properties:
6.1.1 Carbon steel forgings (Grades C through H) and alloy
steel forgings (Grades I through N) shall conform to the
requirements prescribed in Table 4 when tested in accordance
with the latest issue of Test Methods A 370
6.1.2 The size classification of forgings shall be determined
by the specified diameter or thickness of solid forgings
disregarding large ends or collars or by the specified wall
thickness of bored forgings that are heat treated after rough
boring
6.1.3 The diameter of the test prolongation of forgings shall
be the specified diameter or thickness of the forgings disre-garding large ends or collars
6.1.4 Tests of forgings shall be made only after final heat treatment
6.2 Number of Specimens:
6.2.1 Test prolongations shall be attached to at least 5 % of the forgings in each size classification in each heat in each heat treatment lot
6.2.2 Forgings may be used for test procurement if forgings with prolongations are not available or have been expended 6.2.3 Mechanical tests shall be made from each size classi-fication shown in Table 4 in each heat in each annealing or normalizing charge, or from each size classification in each heat in each normalizing or quenching charge represented in each tempering charge
6.2.4 Where batch-type heat treating furnaces are used, one test shall be made from each size classification shown in Table
4 of each heat represented in each annealing or normalizing charge, or from each size classification in eachheat in each normalizing or quenching charge represented in each temper-ing charge
6.2.5 Where continuous heat-treating furnaces are used, one test shall be made from each grade from each size classification shown in Table 4 represented by each heat The pieces represented by each test shall be designated a heat treatment lot, and each lot shall contain no more than 70 pieces from each heat
6.2.6 If any test specimen fails because of mechanical condition of the testing apparatus, it may be discarded and another specimen taken
6.3 Test Location and Orientation:
6.3.1 Test specimens shall be taken from the test prolonga-tion or a forging in accordance with the provisions of 6.2 6.3.2 The axis of the specimen shall be located at any point midway between the center and surface of the solid forging or full-sized prolongation, or at any point midway between the inner and outer surfaces of the wall of bored forgings, and shall
be parallel to the axis of the forging in the direction in which the metal is most drawn out
6.3.3 Test specimens shall conform to dimensions shown in Fig 6 of Test Methods A 370
6.4 Test Method:
6.4.1 The yield point specified in Table 4 for Grades C, D,
E, F, I, and J may be determined by the drop of the beam or halt
of the gage of the testing machine, or by the use of dividers Where a definite yield point is not exhibited, the yield strength defined in 6.4.2 shall be used
6.4.2 The yield strength specified in Table 4 for Grades G,
H, K, L, M, and N forgings shall be determined by a strain gage
or extensometer reading to 0.0002 in (0.005 mm) Yield strength may be defined as the stress at 0.6 % total strain under load or as the stress at 0.2 % offset The procedure described in Test Methods A 370 shall be followed After the yield point has been passed, the extensometer may then be removed and the test continued to determine the tensile strength
TABLE 2 Permissible Variations for Product Analysis of Carbon
Steels
Elements
Permissible Variations, over the Maximum Limit
or Under the Minimum Limit, %
100 in 2
(645 cm 2
) and Under A
Over 100 to 400 in 2
(645 to 2581 cm 2
), incl A
Carbon (Grades A and B) 0.02 0.04
Phosphorus 0.008 0.010
A Determine by cross section from which drillings are taken.
Trang 47 Metallurgical Structure
7.1 For Grades D, E, F, G, H, I, J, and K forgings, one
microscopy test shall be made from each size classification in
each heat represented in each heat treatment lot The entire
specimen shall show a uniform, heat-treated grain size of No
5 or finer measured in accordance with Test Methods E 112
7.2 For grades specified in 7.1, a specimen for the
micro-scopical test shall be cut from the large undistorted portion of
the tension test specimen in such a way as will give a face
transverse to the axis of the forging
8 Workmanship, Finish, and Appearance
8.1 The forgings shall conform to the sizes and shapes
specified by the purchaser When centered, standard 60-deg
centers with clearance drilled for lathe center points shall be
used
8.2 The forgings shall be free of injurious imperfections and
shall have a workmanlike finish
9 Number of Tests and Retests
9.1 If the results of the mechanical tests of any test lot do
not conform to the requirements specified because a flaw
developed in the test specimen during testing, a retest shall be
allowed if the defect is not caused by ruptures, cracks, or flakes
in the steel
10 Reheat Treatment
10.1 If the results of the mechanical tests of any test lot do not conform to the requirements specified, the manufacturer may retreat such lot, but not more than three additional times, and retests shall be made in accordance with Sections 6 and 7, and shall meet the requirements for the grade of forgings involved
11 Inspection
11.1 Inspection of the material shall be made as agreed upon
by the purchaser and manufacturer as part of the purchase contract
12 Rejection and Rehearing
12.1 Rejection:
12.1.1 Any rejection based on tests made in accordance with 5.3 shall be reported to the manufacturer within 5 working days from the receipt of samples by the purchaser
12.1.2 Material that shows injurious imperfections subse-quent to its acceptance at the manufacturer’s works will be rejected, and the manufacturer shall be notified
12.2 Rehearing—Samples tested in accordance with this
specification that represent rejected material, shall be held for
a period of 14 days from the date of notification In case of
TABLE 3 Permissible Variations for Product Analysis of Alloy Steels
Elements Limit, or Maximum of Specified
Element, %
Variation Over Maximum Limit or Under Minimum Limit, %
To 100 in 2
(645 cm 2
)
Over 100 to 200 in 2
(645 to 1290 cm 2 ), incl
Over 200 to 400 in 2
(1290 to 2580 cm 2 ), incl
Over 400 to 800 in 2
(2580 to 5160 cm 2 ), incl Carbon To 0.30, incl
Over 0.30 to 0.75, incl Over 0.75
0.01 0.02 0.03
0.02 0.03 0.04
0.03 0.04 0.05
0.01 0.05 0.06 Manganese To 0.90, incl
Over 0.90 to 2.10, incl
0.03 0.04
0.04 0.05
0.05 0.06
0.06 0.07 Phosphorus Over maximum only 0.005 0.010 0.010 0.010
Silicon To 0.35, incl
Over 0.35 to 2.20, incl
0.02 0.05
0.02 0.06
0.03 0.06
0.04 0.07
Over 1.00 to 2.00, incl 0.05 0.05 0.05 0.05 Over 2.00 to 5.30, incl 0.07 0.07 0.07 0.07 Over 5.30 to 10.00, incl 0.10 0.10 0.10 0.10 Chromium To 0.90, incl
Over 0.90 to 2.10, incl Over 2.10 to 3.99
0.03 0.05 0.10
0.04 0.06 0.10
0.04 0.06 0.12
0.05 0.07 0.14 Molybdenum To 0.20, incl
Over 0.20 to 0.40, incl Over 0.40 to 1.15, incl
0.01 0.02 0.03
0.01 0.03 0.04
0.02 0.03 0.05
0.03 0.04 0.06 Tungsten To 1.00, incl
Over 1.00 to 4.00, incl
0.04 0.08
0.05 0.09
0.05 0.10
0.06 0.12
Over 0.10 to 0.25, incl 0.02 0.02 0.02 0.02 Over 0.25 to 0.50, incl 0.03 0.03 0.03 0.03 Minimum value specified, check under
minimum limit
Trang 5dissatisfaction with the results of the tests, the manufacturer
may request a rehearing within that time
13 Certification
13.1 Upon request of the purchaser in the contract or order,
a manufacturer’s certification that the material was
manufac-tured and tested in accordance with this specification, together
with a report of the test results, shall be furnished at the time
of shipment
14 Product Marking
14.1 Identification marks shall be legibly stamped on each forging and each test specimen The purchaser may indicate the location of such identification marks
14.2 After the material has been inspected, the inspector shall stamp each accepted forging with his private mark
TABLE 4 Tensile Requirements
Size
Grade Solid Diameter or Thickness Bored Wall Thickness A
Tensile Strength, min
Yield Point or Yield Strength, min
Elongation
in 2 in or
50 mm, min, %
Reduction
of Area, min, % Over Not Over Over Not Over
in mm in mm in mm in mm psi MPa psi MPa
C (Annealed, normalized, or
normalized and tempered) B
8 203 8 14 203 356
75 000
75 000
515 515
37 500 C
37 500 C
260 260
20 19
33 31
D (Annealed, normalized, or
normalized and tempered) B
8 203 8 14 203 356
80 000
80 000
550 550
40 000 C
40 000 C
275 275
22 21
35 33
E (Normalized and tempered)
8 203 8 14 203 356
85 000
83 000
585 570
44 000 C
43 000 C
305 295
25 23
40 37
F (Double normalized and
tempered)
8 12
203 305
8 12 14
203 305 356
4
102
4 6
102 152
88 000
86 000
84 000
605 595 580
50 000 C
48 000 C
46 000 C
345 330 315
22 21 20
37 35 33
G (Quenched and tempered) 4 102 2 51 90 000 620 55 000 D
380 20 39
4 102 7 178 2 51 3 1 ⁄ 2 89 85 000 585 50 000 D
345 20 39
7 178 10 254 3 1 ⁄ 2 89 5 127 85 000 585 50 000 D 345 19 37 5 127 8 203 82 500 565 48 000 D 330 19 36
H (Normalized, quenched
and tempered)
7
178
7 10
178 254
4
102
4 8
102 203
115 000
105 000
100 000
795 725 690
75 000 D
65 000 D
60 000 D
515 450 415
16 18 18
35 35 35
I (Normalized and tempered)
8 203 8 20 203 508 4 102 4 8 102 203
80 000
80 000
550 550
55 000 C
55 000 C
380 380
28 28
60 55
J (Normalized and tempered) 5 127 2 1 ⁄ 2 64 90 000 620 60 000 C 415 24 48
5 127 9 229 2 1 ⁄ 2 64 4 1 ⁄ 2 114 90 000 620 60 000 C 415 22 44
9 229 13 330 4 1 ⁄ 2 114 6 1 ⁄ 2 165 90 000 620 58 000 C 400 21 42
13 330 20 508 6 1 ⁄ 2 165 8 203 88 000 605 56 000 C
385 20 40
K (Normalized and tempered) 5 127 2 1 ⁄ 2 64 95 000 655 72 000 D
495 23 55
5 127 9 229 2 1 ⁄ 2 64 4 1 ⁄ 2 114 95 000 655 70 000 D
485 22 53
9 229 13 330 4 1 ⁄ 2 114 6 1 ⁄ 2 165 93 000 640 67 000 D 460 22 50
13 330 20 508 6 1 ⁄ 2 165 8 203 91 000 625 65 000 D 450 21 48
L (Normalized, quenched,
and tempered)
7
178
7 10
178 254
.
3 1 ⁄ 2
5
89 127
3 1 ⁄ 2
5 8
89 127 203
95 000
90 000
85 000
655 620 585
70 000 D
65 000 D
60 000 D
485 450 415
23 20 20
54 50 50
M (Normalized, quenched,
and tempered)
7
178
7 10
178 254
.
3 1 ⁄ 2
5
89 127
3 1 ⁄ 2
5 8
89 127 203
105 000
100 000
95 000
725 690 655
80 000 D
75 000 D
70 000 D
550 515 485
20 19 19
50 50 50
N (Normalized, quenched,
and tempered)
4 7
102 178
4 7 10
102 178 254
2
3 1 ⁄ 2
51 89
2
3 1 ⁄ 2
5
51 89 127
125 000
115 000
110 000
860 795 760
105 000 D
95 000 D
85 000 D
725 655 585
16 16 16
50 45 45
A
Where no figures are shown in the bored wall thickness column, it is understood that the size classification is determined by the outside diameter, whether the forging
is bored or not.
B Alternative treatments specified are optional with the manufacturer.
C
Yield point, see 6.4.1.
D
Yield strength, see 6.4.2.
Trang 614.3 In addition to the above required markings, bar code
tags may be applied to the forgings If these tags are applied, it
is recommended that Bar Code 39 be used The size and
location of the tags, as well as the information to be included,
shall be agreed upon by the purchaser and the manufacturer
15 Keywords
15.1 alloy steel forgings; carbon steel forgings; rail appli-cations
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 shall be agreed upon by the manufacturer and the
purchaser
S1 Chemical Composition
S1.1 The purchaser may specify on Grades A through H that
the residual alloy elements, not intentionally added, shall not
exceed 0.25 % nickel, 0.20 % chromium, and 0.06 %
molyb-denum
S1.2 The purchaser may specify on Grades I through N that
the residual alloy elements, not intentionally added, shall not
exceed 0.35 % copper, 0.25 % nickel, 0.20 % chromium, and
0.06 % molybdenum
S2 Turning
S2.1 The purchaser may specify a preliminary rough
ma-chining prior to the heat treating operation
S3 Macroscopic Tests
S3.1 The prolongation from the largest forging in each heat
shall be sawed normal to the axis of the forging and shall then
be split longitudinally The transverse and longitudinal faces shall be etched for macroscopic examination When macroetch testing of forgings is required, reference shall be made to the latest issue of Method E 381
S4 Boring
S4.1 Boring, as described in 4.5, may be specified
S5 Additional Tests
S5.1 Any testing Sections 6 and 7 shall be a matter of agreement between the manufacturer and the purchaser S5.2 The purchaser may specify mechanical tests of Grades
A and B forgings If mechanical property tests do not conform
to the requirements agreed upon, the manufacturer may anneal
or normalize the lot involved, but not more than three times
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