ASTM A470/A470M-05(2015)
(Specification)Standard Specification for Vacuum-Treated Carbon and Alloy Steel Forgings for Turbine Rotors and Shafts
Standard Specification for Vacuum-Treated Carbon and Alloy Steel Forgings for Turbine Rotors and Shafts
ABSTRACT
This specification covers vacuum-treated carbon and alloy steel forgings for turbine rotors and shafts. Materials shall be manufactured and treated by: melting process via basic electric-furnace; secondary melting process via electrode-electroslag or vacuum-arc remelting; vacuum degassing; forging process via hot mechanical working; heat treatment via double-normalizing and tempering, or normalizing, quenching and tempering; and rough machining and axial boring. Tension and impact tests shall be done to evaluate the conformance of steel forgings with the following mechanical properties: tensile strength and toughness, notch toughness, yield strength, elongation, and reduction of area. Chemical composition conformances shall also be assessed by heat and product analyses. Nondestructive tests, such as ultrasonic and internal examination, and stability tests shall also be performed. Retreatments may be executed one or more times, but not more than three additional times, if results of the mechanical tests do not conform to specified requirements.
SCOPE
1.1 This specification covers vacuum-treated carbon and alloy steel forgings for turbine rotors and shafts.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:A470/A470M −05 (Reapproved 2015)
Standard Specification for
Vacuum-Treated Carbon and Alloy Steel Forgings for
Turbine Rotors and Shafts
This standard is issued under the fixed designationA470/A470M; 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 U.S. Department of Defense.
1. Scope E139 Test Methods for Conducting Creep, Creep-Rupture,
and Stress-Rupture Tests of Metallic Materials
1.1 This specification covers vacuum-treated carbon and
alloy steel forgings for turbine rotors and shafts.
3. Ordering Information and General Requirements
1.2 The values stated in either SI units or inch-pound units
3.1 Material supplied to this specification shall conform to
are to be regarded separately as standard. The values stated in
the requirements of Specification A788/A788M, which out-
each system may not be exact equivalents; therefore, each
lines additional ordering information, manufacturing methods
system shall be used independently of the other. Combining
and procedures, marking, certification, production analysis
values from the two systems may result in non-conformance
variations, and additional supplementary requirements.
with the standard.
3.2 In addition to the ordering information required by
1.3 This standard does not purport to address all of the
Specification A788/A788M, the purchaser shall include with
safety concerns, if any, associated with its use. It is the
the inquiry and order, the grade and class of steel, alternative
responsibility of the user of this standard to establish appro-
maximum for silicon content (see Table 1), the choice of yield
priate safety and health practices and determine the applica-
strength offset (0.2 or 0.02 %), and any tests, supplementary
bility of regulatory limitations prior to use.
requirements, and purchase options desired.
2. Referenced Documents
3.3 Forging Drawing—Each forging shall be manufactured
2.1 ASTM Standards:
in accordance with a drawing furnished by the purchaser
A275/A275M Practice for Magnetic Particle Examination of
showing the dimensions of the forging and bore hole, if any,
Steel Forgings
and the location of mechanical test specimens.
A293 SpecificationforSteelForgings,CarbonandAlloy,for
3.4 Supplementary Requirements—Supplementary require-
Turbine Generator Rotors and Shafts; Replaced by A 470
ments are provided. These requirements shall apply only when
(Withdrawn 1984)
specified in the purchase order.
A370 Test Methods and Definitions for Mechanical Testing
3.5 If the requirements of this specification are in conflict
of Steel Products
with the requirements of Specification A788/A788M, the
A418/A418M Practice for Ultrasonic Examination of Tur-
requirements of this specification shall prevail.
bine and Generator Steel Rotor Forgings
A472/A472M Specification for Heat Stability of Steam Tur-
4. Manufacture
bine Shafts and Rotor Forgings
A788/A788M Specification for Steel Forgings, General Re- 4.1 Melting Process:
quirements 4.1.1 The steel shall be made by the basic electric-furnace
process.
4.1.2 Provisions for subsequent secondary melting of the
This specification is under the jurisdiction ofASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
steel by the consumable electrode-electroslag or vacuum-arc
A01.06 on Steel Forgings and Billets.
remelting processes are included in Supplementary Require-
Current edition approved March 1, 2015. Published March 2015. Originally
ment S7.
approved in 1962. Last previous edition approved in 2010 as A470/A470M – 05
(2010). DOI: 10.1520/A0470_A0470M-05R15.
4.2 Vacuum Treatment—The vacuum degassing require-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ments of Specification A788/A788M are mandatory.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
4.3 Discard—Sufficient discard shall be taken from each
the ASTM website.
3 ingot to secure freedom from pipe and harmful segregation in
The last approved version of this historical standard is referenced on
www.astm.org. the finished forging.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A470/A470M−05 (2015)
A
TABLE 1 Chemical Requirements
Grade A Grade B Grade C Grade D Grade E
Ni-Mo-V Ni-Mo-V Ni-Cr-Mo-V Cr-Mo-V Ni-Mo-V
Carbon 0.22–0.30 0.22–0.30 0.28 0.25–0.35 0.30
Manganese 0.20–0.60 0.20–0.60 0.20–0.60 1.00 0.70
Phosphorus 0.012 0.012 0.012 0.012 0.025
Sulfur 0.012 0.012 0.015 0.015 0.025
BBB,CB B
Silicon
Nickel 3.20–3.70 3.20–3.70 3.25–4.00 0.75 2.00 min.
Chromium 0.75 0.75 1.25–2.00 1.05–1.50 0.75
D
Molybdenum 0.40–0.60 0.40–0.60 0.25–0.60 1.00–1.50 0.25 min
Vanadium 0.04–0.12 0.04–0.12 0.05–0.15 0.20–0.30 0.03–0.12
EEEE E
Antimony
F
Aluminum 0.015 0.015 0.015 0.015 0.015
G
Equivalent . . . Classes 2 and 3 .
Specification A293
Grade Designation (replaced by
Specification A470)
A
Maximum or range, unless otherwise indicated.
B
0.10 % max, unless an alternative value, not in excess of 0.30 %, is specified in the purchase order.
C
0.15 to 0.30 % silicon is permitted for material that is subsequently VAR Processed.
D
Supplementary Requirement, see S1.
E
To be reported for information only on all Grades.
F
Total of soluble and insoluble.
G
Phosphorus of 0.035 max and sulfur of 0.035 max were specified for Specification A293.
4.4 Forging Process—The forging shall receive its hot mechanicalpropertiesshallbemadeafterthesecondtempering
mechanical work under a press of ample power to adequately operation. Mechanical property tests after the first temper are
work the metal throughout the maximum section of the optional with the manufacturer.
forging. It is important to maintain the axial center of the
4.5.1.4 After heat treatment and subsequent rough machin-
forging in common with the axial center of the ingot.
ing and axial boring (see 4.6.2 and 4.6.3), the forging shall be
stress-relieved at a temperature not more than 100°F [55°C]
4.5 Heat Treatment:
below the final tempering temperature, but not less than
4.5.1 The heat treatment for mechanical properties shall
1025°F [550°C].
consist of double-normalizing and tempering for Grades A, B,
4.5.1.5 With the prior approval of the purchaser, the stress-
D,andEandnormalizing,quenching,andtemperingforGrade
relief temperature may approach, equal, or slightly exceed the
C. In normalizing treatments, the forging may be cooled in still
final tempering temperature as a means of adjusting final
air or in an air blast at the manufacturer’s option. Faster
strength or toughness. If the stress-relief temperature is within
cooling rates for Grades A, B, D, and E may be used if
25°F [14°C] of the final tempering temperature, or higher,
authorized by the purchaser. These rates are obtained by liquid
additional tension tests must be obtained (6.1.3).
quenching, or by the addition of water sprays of fog to the air
blast.
4.6 Machining:
4.5.1.1 The first normalizing treatment shall be from well
4.6.1 Preliminary Rough Machining—All exterior surfaces
above the transformation temperature range. At the manufac-
of the forging shall be machined prior to heat treatment for
turer’s option, this operation may be performed as a part of the
mechanical properties.
preliminary treatment of the forging before preliminary ma-
4.6.2 Second Rough Machining—After heat treatment for
chining (see 4.6.1).
mechanicalproperties,allsurfacesoftheforgingshallberough
4.5.1.2 The second normalizing or quenching treatment
machined prior to stress relief and the stability test.
shallbefromabovethetransformationrangebutbelowthefirst
4.6.3 Axial Bore:
normalizing temperature described in 4.5.1.1. This treatment
4.6.3.1 Forgings shall be bored to permissible bore size and
shall be performed after preliminary machining (see 4.6.1).
tolerance when required by the purchaser’s drawing.
4.5.1.3 The final tempering temperature for GradesA, B, C,
4.6.3.2 Forgings may be bored to limits agreed to by the
and E shall be not less than 1075°F [580°C] and for Grade D
purchaser, or indicated on the purchaser’s drawing, to remove
not less than 1200°F [650°C].With prior purchaser approval, a
objectionable center conditions revealed by ultrasonic exami-
second tempering operation shall be performed prior to the
nation.
operations described in 4.6.2 and 4.6.3 to complete the heat
4.6.3.3 Unless otherwise specified by the purchaser, the
treatment cycle. This second temper will be in place of the
manufacturer may bore the forging at any time prior to stress
stress relief specified in 4.5.1.4 and 4.5.1.5 and the tempera-
relief (see Supplementary Requirement S2).
tures applied to the second temper will meet the temperature
limits in 4.5.1.4. However, with the prior approval of the 4.6.4 Machining to Purchaser’s Requirements for
purchaser, the second tempering temperature may be equal, or Shipment—The forging as shipped shall conform to the finish
slightly exceed, the first tempering temperature as a means of and dimension requirements specified on the purchaser’s
adjusting final strength or toughness. The required tests for drawing or order.
A470/A470M−05 (2015)
5. Chemical Composition purchaser’s drawing. The specimens shall be Charpy V-notch,
as shown in Test Methods and Definitions A370. The notch
5.1 Thesteelshallconformtotherequirementsforchemical
direction of the Charpy specimens shall be tangential.
composition prescribed in Table 1.
6.3 The properties at the axial bore region may not neces-
5.2 Chemical Analysis:
sarily be the same as those determined at the surface radial or
5.2.1 Product Analysis—The manufacturer shall make a
axial prolongation regions. Slight variations in chemical
product analysis from each forging. The sample location and
homogeneity, different cooling rates, presence of non-
product analysis tolerances shall conform to Specification
metallics, and orientation of the test samples are some of the
A788/A788M.
factors that can contribute to the difference. If axial bore
properties are required, they can be obtained through Supple-
6. Mechanical Properties
mentary Requirement S2.
6.1 Tension Test:
6.1.1 The steel shall conform to the tensile requirements of
7. Dimensions, Tolerances, and Finish
Table 2.
7.1 The steel shall conform to the tensile requirements of
6.1.2 The number and location of tension test specimens
Table 2.
shall be as specified on the drawing furnished by the purchaser.
7.2 The finish on each forging shall conform to the finish
6.1.3 Final acceptance tests shall be made after heat treat-
specified on the purchaser’s drawing or order.
ment of the forging for mechanical properties prior to stress
relief,unlessthestressrelieftemperatureiswithin25°F[14°C]
8. Nondestructive Tests
of the tempering temperature, or higher, in which case check
tests shall be made after the stress relief treatment and reported 8.1 General Requirements:
to the purchaser. The purchaser may require check tests after 8.1.1 The forgings shall be free of cracks, seams, laps,
completion of all heating cycles, including stress relief and the shrinkage, and similar imperfections.
heat stability tests. 8.1.2 The purchaser may request ultrasonic, magnetic
6.1.4 Testing shall be performed in accordance with the particle, dye penetrant, etch, or other accepted nondestructive
latest revision of Test Methods and Definitions A370. Tension examination necessary to evaluate imperfections and ensure
specimens shall be the standard 0.5-in. diameter by 2-in. gage compliance with this requirement.
length [or 12.5- by 50.0-mm type] as shown in Test Methods
8.2 Ultrasonic Examination:
and Definitions A370.
8.2.1 An ultrasonic examination shall be made on the
6.1.5 The yield strength prescribed in Table 2 shall be
machined forging at the manufacturer’s plant. This examina-
determined by the offset method of Test Methods and Defini-
tionshallbemadeinaccordancewithPracticeA418/A418Mto
tions A370.
demonstrate freedom from rejectable internal indications.
6.2 Impact Test: 8.2.2 The ultrasonic examination shall be made from all
6.2.1 The steel shall conform to the requirements for notch available surfaces prior to removal of test specimens that
toughness (both transition temperature and room temperature would interfere with complete testing of the forging.
impact values) prescribed in Table 2. 8.2.3 Forgings with recordable ultrasonic indications shall
6.2.2 The impact specimens shall be machined from radial be referred to the purchaser for evaluation based on the nature,
bars taken from the main body of the forging, as shown in the frequency, and location of indications, both stationary and
TABLE 2 Tensile and Notch Toughness Requirements
Grade A Grade B Grade C Grade D Grade E
Class 2 Class 3 Class 4 Class 5 Class 6 Class 7 Class 8 Class 9
Tensile strength, 80 [550] 90 [620] 105 [725] 90 to 110 105 to 125 120 to 135 105 to 125 95 [655]
min, ksi [MPa] [620–760] [725–860] [825–930] [725–860]
Yield strength, 55 [380] 70 [485] 85 [585] 70 [485] 85 [585] 95 [655] 85 [585] 70 [485]
min, ksi [MPa]
0.2 % offset 60 [415] 75 [520] 90 [620] 75 [520] 90 [620] 100 [690] 90 [620] 75 [520]
0.02 % offset 55 [380] 70 [485] 85 [585] 70 [485] 85 [585] 95 [655] 85 [585] 70 [485]
Elongation in 2 in. or
50 mm, min, %:
Longitudinal 22 20 17 20 18 18 17 20
prolongation
Radial body 20 17 16 18 17 17 14 15
Reduction of area,
min, %:
Longitudinal 50 48 45 52 52 52 43 40
prolongation
Radial body 50 45 40 50 50 50 38 35
Transition temperature 100 [38] 110 [43] 140 [60] 10 [−12] 20 [−7] 30 [−1] 250 [121] 175 [80]
FATT max, °F [°C]
Room temperature 28 [38] 25 [34] 20 [27] 50 [68] 45 [61] 40 [54] 6 [8] 12 [16]
impact, min, ft·lbf [J]
A470/A470M−05 (2015)
traveling. If the ultrasonic indications are considered 10.3 If complete retreatment, including normalizing or
objectionable, it shall be determined by conventional or mutu- quenching, is necessary after boring, the feasibility of retreat-
ally acceptable examination procedures whether the forging ing portions of the bore core in the bore of the forging shall be
will be rejected. discussed between manufacturer and purchaser and a proce-
dure agreed upon before retreatment.
8.3 Internal Examination:
8.3.1 Axial bore, when specified for internal visual
11. Certification and Reports
examination,shallbeinac
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A470/A470M − 05 (Reapproved 2010) A470/A470M − 05 (Reapproved 2015)
Standard Specification for
Vacuum-Treated Carbon and Alloy Steel Forgings for
Turbine Rotors and Shafts
This standard is issued under the fixed designation A470/A470M; 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 U.S. Department of Defense.
1. Scope
1.1 This specification covers vacuum-treated carbon and alloy steel forgings for turbine rotors and shafts.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
A275/A275M Practice for Magnetic Particle Examination of Steel Forgings
A293 Specification for Steel Forgings, Carbon and Alloy, for Turbine Generator Rotors and Shafts; Replaced by A 470
(Withdrawn 1984)
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A418/A418M Practice for Ultrasonic Examination of Turbine and Generator Steel Rotor Forgings
A472/A472M Specification for Heat Stability of Steam Turbine Shafts and Rotor Forgings
A788/A788M Specification for Steel Forgings, General Requirements
E139 Test Methods for Conducting Creep, Creep-Rupture, and Stress-Rupture Tests of Metallic Materials
3. Ordering Information and General Requirements
3.1 Material supplied to this specification shall conform to the requirements of Specification A788/A788M, which outlines
additional ordering information, manufacturing methods and procedures, marking, certification, production analysis variations, and
additional supplementary requirements.
3.2 In addition to the ordering information required by Specification A788/A788M, the purchaser shall include with the inquiry
and order, the grade and class of steel, alternative maximum for silicon content (see Table 1), the choice of yield strength offset
(0.2 or 0.02 %), and any tests, supplementary requirements, and purchase options desired.
3.3 Forging Drawing—Each forging shall be manufactured in accordance with a drawing furnished by the purchaser showing
the dimensions of the forging and bore hole, if any, and the location of mechanical test specimens.
3.4 Supplementary Requirements—Supplementary requirements are provided. These requirements shall apply only when
specified in the purchase order.
3.5 If the requirements of this specification are in conflict with the requirements of Specification A788/A788M, the
requirements of this specification shall prevail.
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.
Current edition approved April 1, 2010March 1, 2015. Published May 2010March 2015. Originally approved in 1962. Last previous edition approved in 20052010 as
ε1
A470/A470M – 05 (2010). . DOI: 10.1520/A0470_A0470M-05E01.10.1520/A0470_A0470M-05R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A470/A470M − 05 (2015)
A
TABLE 1 Chemical Requirements
Grade A Grade B Grade C Grade D Grade E
Ni-Mo-V Ni-Mo-V Ni-Cr-Mo-V Cr-Mo-V Ni-Mo-V
Carbon 0.22–0.30 0.22–0.30 0.28 0.25–0.35 0.30
Manganese 0.20–0.60 0.20–0.60 0.20–0.60 1.00 0.70
Phosphorus 0.012 0.012 0.012 0.012 0.025
Sulfur 0.012 0.012 0.015 0.015 0.025
B B B,C B B
Silicon
Nickel 3.20–3.70 3.20–3.70 3.25–4.00 0.75 2.00 min.
Chromium 0.75 0.75 1.25–2.00 1.05–1.50 0.75
D
Molybdenum 0.40–0.60 0.40–0.60 0.25–0.60 1.00–1.50 0.25 min
Vanadium 0.04–0.12 0.04–0.12 0.05–0.15 0.20–0.30 0.03–0.12
E E E E E
Antimony
F
Aluminum 0.015 0.015 0.015 0.015 0.015
G
Equivalent . . . Classes 2 and 3 .
Specification A293
Grade Designation (replaced by
Specification A470)
A
Maximum or range, unless otherwise indicated.
B
0.10 % max, unless an alternative value, not in excess of 0.30 %, is specified in the purchase order.
C
0.15 to 0.30 % silicon is permitted for material that is subsequently VAR Processed.
D
Supplementary Requirement, see S1.
E
To be reported for information only on all Grades.
F
Total of soluble and insoluble.
G
Phosphorus of 0.035 max and sulfur of 0.035 max were specified for Specification A293.
4. Manufacture
4.1 Melting Process:
4.1.1 The steel shall be made by the basic electric-furnace process.
4.1.2 Provisions for subsequent secondary melting of the steel by the consumable electrode-electroslag or vacuum-arc remelting
processes are included in Supplementary Requirement S7.
4.2 Vacuum Treatment—The vacuum degassing requirements of Specification A788/A788M are mandatory.
4.3 Discard—Sufficient discard shall be taken from each ingot to secure freedom from pipe and harmful segregation in the
finished forging.
4.4 Forging Process—The forging shall receive its hot mechanical work under a press of ample power to adequately work the
metal throughout the maximum section of the forging. It is important to maintain the axial center of the forging in common with
the axial center of the ingot.
4.5 Heat Treatment:
4.5.1 The heat treatment for mechanical properties shall consist of double-normalizing and tempering for Grades A, B, D, and
E and normalizing, quenching, and tempering for Grade C. In normalizing treatments, the forging may be cooled in still air or in
an air blast at the manufacturer’s option. Faster cooling rates for Grades A, B, D, and E may be used if authorized by the purchaser.
These rates are obtained by liquid quenching, or by the addition of water sprays of fog to the air blast.
4.5.1.1 The first normalizing treatment shall be from well above the transformation temperature range. At the manufacturer’s
option, this operation may be performed as a part of the preliminary treatment of the forging before preliminary machining (see
4.6.1).
4.5.1.2 The second normalizing or quenching treatment shall be from above the transformation range but below the first
normalizing temperature described in 4.5.1.1. This treatment shall be performed after preliminary machining (see 4.6.1).
4.5.1.3 The final tempering temperature for Grades A, B, C, and E shall be not less than 1075°F [580°C] and for Grade D not
less than 1200°F [650°C]. With prior purchaser approval, a second tempering operation shall be performed prior to the operations
described in 4.6.2 and 4.6.3 to complete the heat treatment cycle. This second temper will be in place of the stress relief specified
in 4.5.1.4 and 4.5.1.5 and the temperatures applied to the second temper will meet the temperature limits in 4.5.1.4. However, with
the prior approval of the purchaser, the second tempering temperature may be equal, or slightly exceed, the first tempering
temperature as a means of adjusting final strength or toughness. The required tests for mechanical properties shall be made after
the second tempering operation. Mechanical property tests after the first temper are optional with the manufacturer.
4.5.1.4 After heat treatment and subsequent rough machining and axial boring (see 4.6.2 and 4.6.3), the forging shall be
stress-relieved at a temperature not more than 100°F [55°C] below the final tempering temperature, but not less than 1025°F
[550°C].
4.5.1.5 With the prior approval of the purchaser, the stress-relief temperature may approach, equal, or slightly exceed the final
tempering temperature as a means of adjusting final strength or toughness. If the stress-relief temperature is within 25°F
(14°C)[14°C] of the final tempering temperature, or higher, additional tension tests must be obtained (6.1.3).
4.6 Machining:
A470/A470M − 05 (2015)
4.6.1 Preliminary Rough Machining—All exterior surfaces of the forging shall be machined prior to heat treatment for
mechanical properties.
4.6.2 Second Rough Machining—After heat treatment for mechanical properties, all surfaces of the forging shall be rough
machined prior to stress relief and the stability test.
4.6.3 Axial Bore:
4.6.3.1 Forgings shall be bored to permissible bore size and tolerance when required by the purchaser’s drawing.
4.6.3.2 Forgings may be bored to limits agreed to by the purchaser, or indicated on the purchaser’s drawing, to remove
objectionable center conditions revealed by ultrasonic examination.
4.6.3.3 Unless otherwise specified by the purchaser, the manufacturer may bore the forging at any time prior to stress relief (see
Supplementary Requirement S2).
4.6.4 Machining to Purchaser’s Requirements for Shipment—The forging as shipped shall conform to the finish and dimension
requirements specified on the purchaser’s drawing or order.
5. Chemical Composition
5.1 The steel shall conform to the requirements for chemical composition prescribed in Table 1.
5.2 Chemical Analysis:
5.2.1 Product Analysis—The manufacturer shall make a product analysis from each forging. The sample location and product
analysis tolerances shall conform to Specification A788/A788M.
6. Mechanical Properties
6.1 Tension Test:
6.1.1 The steel shall conform to the tensile requirements of Table 2.
6.1.2 The number and location of tension test specimens shall be as specified on the drawing furnished by the purchaser.
6.1.3 Final acceptance tests shall be made after heat treatment of the forging for mechanical properties prior to stress relief,
unless the stress relief temperature is within 25°F [14°C] of the tempering temperature, or higher, in which case check tests shall
be made after the stress relief treatment and reported to the purchaser. The purchaser may require check tests after completion of
all heating cycles, including stress relief and the heat stability tests.
6.1.4 Testing shall be performed in accordance with the latest revision of Test Methods and Definitions A370. Tension
specimens shall be the standard 0.5-in. diameter by 2-in. gage length [or 12.5- by 50.0-mm type] as shown in Test Methods and
Definitions A370.
6.1.5 The yield strength prescribed in Table 2 shall be determined by the offset method of Test Methods and Definitions A370.
6.2 Impact Test:
6.2.1 The steel shall conform to the requirements for notch toughness (both transition temperature and room temperature impact
values) prescribed in Table 2.
6.2.2 The impact specimens shall be machined from radial bars taken from the main body of the forging, as shown in the
purchaser’s drawing. The specimens shall be Charpy V-notch, as shown in Test Methods and Definitions A370. The notch direction
of the Charpy specimens shall be tangential.
6.3 The properties at the axial bore region may not necessarily be the same as those determined at the surface radial or axial
prolongation regions. Slight variations in chemical homogeneity, different cooling rates, presence of non-metallics, and orientation
of the test samples are some of the factors that can contribute to the difference. If axial bore properties are required, they can be
obtained through Supplementary Requirement S2.
7. Dimensions, Tolerances, and Finish
7.1 The steel shall conform to the tensile requirements of Table 2.
7.2 The finish on each forging shall conform to the finish specified on the purchaser’s drawing or order.
8. Nondestructive Tests
8.1 General Requirements:
8.1.1 The forgings shall be free of cracks, seams, laps, shrinkage, and similar imperfections.
8.1.2 The purchaser may request ultrasonic, magnetic particle, dye penetrant, etch, or other accepted nondestructive
examination necessary to evaluate imperfections and ensure compliance with this requirement.
8.2 Ultrasonic Examination:
8.2.1 An ultrasonic examination shall be made on the machined forging at the manufacturer’s plant. This examination shall be
made in accordance with Test Method Practice A418/A418M to demonstrate freedom from rejectable internal indications.
8.2.2 The ultrasonic examination shall be made from all available surfaces prior to removal of test specimens that would
interfere with complete testing of the forging.
A470/A470M − 05 (2015)
TABLE 2 Tensile and Notch Toughness Requirements
Grade A Grade B Grade C Grade D Grade E
Class 2 Class 3 Class 4 Class 5 Class 6 Class 7 Class 8 Class 9
Tensile strength, 80 [550] 90 [620] 105 [725] 90 to 110 105 to 125 120 to 135 105 to 125 95 [655]
min, ksi [620–760] [725–860] [825–930] [725–860]
[MPa]
Yield strength, 55 [380] 70 [485] 85 [585] 70 [485] 85 [585] 95 [655] 85 [585] 70 [485]
min, ksi [MPa]
0.2 % offset 60 [415] 75 [520] 90 [620] 75 [520] 90 [620] 100 [690] 90 [620] 75 [520]
0.02 % offset 55 [380] 70 [485] 85 [585] 70 [485] 85 [585] 95 [655] 85 [585] 70 [485]
Elongation in 2
in.
or 50 mm,
min, %:
Longitudinal 22 20 17 20 18 18 17 20
prolongation
Radial body 20 17 16 18 17 17 14 15
Reduction of
area,
min, %:
Longitudinal 50 48 45 52 52 52 43 40
prolongation
Radial body 50 45 40 50 50 50 38 35
Transition tem- 100 [38] 110 [43] 140 [60] 10 [−12] 20 [−7] 30 [−1] 250 [121] 175 [80]
perature
FATT max,
°F [°C]
Room tempera- 28 [38] 25 [34] 20 [27] 50 [68] 45 [61] 40 [54] 6 [8] 12 [16]
ture impact,
min, ft·lbf [J]
TABLE 2 Tensile and Notch Toughness Requirements
Grade A Grade B Grade C Grade D Grade E
Class 2 Class 3 Class 4 Class 5 Class 6 Class 7 Class 8 Class 9
Tensile strength, 80 [550] 90 [620] 105 [725] 90 to 110 105 to 125 120 to 135 105 to 125 95 [655]
min, ksi [MPa] [620–760] [725–860] [825–930] [725–860]
Yield strength, 55 [380] 70 [485] 85 [585] 70 [4
...
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