ASTM A470/A470M-05(2010)
(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 2010)
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 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 April 1, 2010. Published May 2010. Originally
ϵ1
ment S7.
approved in 1962. Last previous edition approved in 2005 as A470/A470M – 05 .
DOI: 10.1520/A0470_A0470M-05E01.
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 (2010)
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 (2010)
5. Chemical Composition 6.2.1 The steel shall conform to the requirements for notch
toughness (both transition temperature and room temperature
5.1 Thesteelshallconformtotherequirementsforchemical
impact values) prescribed in Table 2.
composition prescribed in Table 1.
6.2.2 The impact specimens shall be machined from radial
5.2 Chemical Analysis:
bars taken from the main body of the forging, as shown in the
5.2.1 Product Analysis—The manufacturer shall make a
purchaser’s drawing. The specimens shall be Charpy V-notch,
product analysis from each forging. The sample location and
as shown in Test Methods and Definitions A370. The notch
product analysis tolerances shall conform to Specification
direction of the Charpy specimens shall be tangential.
A788/A788M.
6.3 The properties at the axial bore region may not neces-
sarily be the same as those determined at the surface radial or
6. Mechanical Properties
axial prolongation regions. Slight variations in chemical ho-
6.1 Tension Test:
mogeneity, different cooling rates, presence of non-metallics,
6.1.1 The steel shall conform to the tensile requirements of
and orientation of the test samples are some of the factors that
Table 2.
can contribute to the difference. If axial bore properties are
6.1.2 The number and location of tension test specimens
required, they can be obtained through Supplementary Re-
shall be as specified on the drawing furnished by the purchaser.
quirement S2.
6.1.3 Final acceptance tests shall be made after heat treat-
ment of the forging for mechanical properties prior to stress
7. Dimensions, Tolerances, and Finish
relief,unlessthestressrelieftemperatureiswithin25°F[14°C]
7.1 The steel shall conform to the tensile requirements of
of the tempering temperature, or higher, in which case check
Table 2.
tests shall be made after the stress relief treatment and reported
7.2 The finish on each forging shall conform to the finish
to the purchaser. The purchaser may require check tests after
specified on the purchaser’s drawing or order.
completion of all heating cycles, including stress relief and the
heat stability tests.
8. Nondestructive Tests
6.1.4 Testing shall be performed in accordance with the
latest revision of Test Methods and Definitions A370. Tension 8.1 General Requirements:
specimens shall be the standard 0.5-in. diameter by 2-in. gage 8.1.1 The forgings shall be free of cracks, seams, laps,
length [or 12.5- by 50.0-mm type] as shown in Test Methods shrinkage, and similar imperfections.
and Definitions A370. 8.1.2 The purchaser may request ultrasonic, magnetic par-
6.1.5 The yield strength prescribed in Table 2 shall be ticle, dye penetrant, etch, or other accepted nondestructive
determined by the offset method of Test Methods and Defini- examination necessary to evaluate imperfections and ensure
tions A370. compliance with this requirement.
6.2 Impact Test: 8.2 Ultrasonic Examination:
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]
A470/A470M−05 (2010)
8.2.1 An ultrasonic examination shall be made on the may retreat the forging one or more times, but not more than
machined forging at the manufacturer’s plant. This examina- three additional times, without the approval of the purchaser.
tion shall be made in accordance with Test Method A418/
10.2 If bore core properties are specified under Supplemen-
A418M to demonstrate freedom from rejectable internal indi-
tary Requirement S2 and retemper is necessary after boring,
cations.
the remaining portions of the bore core shall be replaced in the
8.2.2 The ultrasonic examination shall be made from all
bore during retemper.
available surfaces prior to removal of test specimens that
10.3 If complete retreatment, including normalizing or
would interfere with complete testing of the forging.
quenching, is necessary after boring, the feasibility of retreat-
8.2.3 Forgings with recordable ultrasonic indications shall
ing portions of the bore core in the bore of the forging shall be
be referred to the purchaser for evaluation based on the nature,
discussed between manufacturer and purchaser and a proce-
frequency, and location of indications, both stationary and
dure agreed upon befor
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