ASTM A471-94(1999)

Standard Specification for Vacuum-Treated Alloy Steel Forgings for Turbine Rotor Disks and Wheels

SCOPE
1.1 This specification covers vacuum-treated alloy steel forgings intended for use as turbine rotor disks and wheels.  
1.2 The values stated in inch-pound units are to be regarded as the standard.

General Information

• Status: Historical
• Publication Date: 09-Sep-1999
• ICS: 77.140.85 - Iron and steel forgings
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.06 - Steel Forgings and Billets

Relations

• Replaced By: ASTM A471-02 - Standard Specification for Vacuum-Treated Alloy Steel Forgings for Turbine Rotor Disks and Wheels
• Effective Date: 10-Sep-2002

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: A 471 – 94 (Reapproved 1999)
Standard Specification for
Vacuum-Treated Alloy Steel Forgings for Turbine Rotor
Disks and Wheels
This standard is issued under the fixed designation A 471; 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 4.2 Vacuum Degassing:
4.2.1 The molten steel shall be vacuum treated prior to or
1.1 This specification covers vacuum-treated alloy steel
during the pouring of the ingot, in order to remove objection-
forgings intended for use as turbine rotor disks and wheels.
able gases, particularly hydrogen.
1.2 The values stated in inch-pound units are to be regarded
4.2.1.1 When the vacuum stream degassing process is
as the standard.
used, the vacuum system must be of sufficient capacity to effect
2. Referenced Documents a blank-off pressure low enough (usually less than 1000 μm) to
break up the normal tight, rope-like stream of molten metal
2.1 ASTM Standards:
into a wide-angled conical stream of relatively small droplets.
A 275/A 275M Test Method for Magnetic Particle Exami-
The capacity of the system must also be sufficiently high to
nation of Steel Forgings
reduce the initial surge pressure at the start of the pour to a low
A 370 Test Methods and Definitions for Mechanical Testing
level within 2 min.
of Steel Products
4.2.1.2 When the vacuum-lift process is utilized, the mol-
A 388/A 388M Practice for Ultrasonic Examination of
ten metal shall be repeatedly drawn into the evacuated vessel to
Heavy Steel Forgings
give a recirculation factor (Note 1) of at least 2.5 to ensure
E 30 Test Methods for Chemical Analysis of Steel, Cast
thorough degassing and mixing of the entire heat. The evacu-
Iron, Open-Hearth Iron, and Wrought Iron
ation system shall be capable of reducing the pressure surges,
E 139 Practice for Conducting Creep, Creep-Rupture, and
which occur each time a new portion of steel is admitted to the
Stress-Rupture Tests of Metallic Materials
vessel, to increasingly lower levels until a blank-off pressure
3. Ordering Information
(usually less than 1000 μm) is achieved.
3.1 The purchaser shall specify in the inquiry and order the
NOTE 1—The recirculation factor is obtained as follows:
class of steel desired and test and purchase options (see 4.5.5,
tons of steel lifted per cycle 3 number of cycles
5.2.2, 6.1, 6.3, 7, and 15.1).
heat weight in tons
3.2 Forging Drawing—Each forging shall be manufactured
4.2.1.3 When the ladle degassing process is used, the
in accordance with a purchaser-supplied drawing showing the
evacuation system shall be capable of reducing the system
finished dimensions and the locations of mechanical test
vacuum pressure to a low level (usually less than 1000 μm).
specimens.
The molten metal shall be adequately stirred for a sufficient
3.3 Supplementary requirements are provided and shall
length of time to maximize exposure to the evacuated atmo-
apply only when specified in the purchaser’s order.
sphere. When this process is used, hydrogen testing per
4. Materials and Manufacture
Supplemental Requirement S2 is mandatory.
4.2.1.4 Other methods of degassing may be used if the
4.1 Melting Process—The steel shall be made by one or
supplier can demonstrate their adequacy to the satisfaction of
more of the following processes: electric-arc, electric-
the purchaser. When other processes are used, hydrogen testing
induction, or consumable-electrode.
per the supplemental requirement S2 is mandatory.
4.3 Discard—Sufficient discard shall be taken from each
This specification is under the jurisdiction of ASTM Committee A-1 on Steel,
ingot to secure freedom from pipe and undue segregation in the
Stainless Steel, and Related Alloys, and is the direct responsibility of Subcommittee
finished forging.
A01.06 on Steel Forgings and Billets.
Current edition approved June 15, 1994. Published August 1994. Originally
published as A 471 – 62 T. Last previous edition A 471 – 93.
Annual Book of ASTM Standards, Vol 01.05.
3 6
Annual Book of ASTM Standards, Vol 01.03. Details of the vacuum stream degassing process may be found in the Journal
Annual Book of ASTM Standards, Vol 03.05. of the Iron and Steel Institute, Vol 191, January 1959; “Vacuum Pouring of Ingots
Annual Book of ASTM Standards, Vol 03.01. for Heavy Forgings” by J. H. Stoll.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
A 471 – 94 (1999)
4.4 Forging Process—The forgings shall receive their hot 4.6 Machining:
mechanical work under a press, hammer, or mill of sufficient 4.6.1 Preliminary Machining—The forgings shall be pre-
power to work the metal throughout its section. The forgings liminarily machined on all surfaces prior to heat treatment for
shall be upset by forming from a block having an axial length mechanical properties (see 4.5.3).
before upsetting of at least two times the thickness of the 4.6.2 Machining to Purchaser’s Requirements for
forging after upsetting. Shipment—After heat treatment for mechanical properties (see
4.4.1 The as-forged dimensions of each forging shall be 4.5.3), the forgings shall be machined to the dimensions of the
planned so the metal is shaped by forging as close as is purchaser’s forging drawing or instructions on his order.
practical to the dimensions shown on the purchaser’s drawing
5. Chemical Composition
so as to keep subsequent machining to a minimum.
4.4.2 The axial center of the forging shall be maintained in 5.1 The steel shall conform to the requirements for chemical
common with the axial center of the ingot. composition prescribed in Table 1.
4.5 Heat Treatment: 5.2 Chemical Analysis:
4.5.1 Cooling Prior to Heat Treatment— After forging and 5.2.1 Heat Analysis—An analysis of each heat of steel shall
before reheating for heat treatment, the forging shall be be made by the manufacturer to determine the percentages of
allowed to cool in a manner to prevent damage and to those elements specified in Table 1. This analysis shall be made
accomplish transformation. from a test ingot taken during the pouring of the heat.
4.5.2 Preliminary Heat Treatment—The forgings shall be 5.2.1.1 If the test sample taken for the ladle analysis is lost
given such preliminary heat treatment as is proper for the or declared inadequate for chemical determinations, the manu-
design and composition. The forgings shall be heated to a facturer may take alternative samples from appropriate loca-
suitable temperature for a sufficient length of time for complete tions near the surface of the ingot or forging as necessary to
austenitization and shall be suitably cooled to bring about establish the analysis of the heat in question.
complete transformation. 5.2.2 Product Analysis—A product analysis may be made
4.5.3 Heat Treatment for Mechanical Properties—The forg- by the purchaser on each forging. Sample for an analysis may
ings shall be reheated to a temperature above the upper critical be taken from the forging at any point from the mid-radius to
temperature, held a sufficient length of time for complete the outside diameter or from a full-size prolongation, or
austenitization, and liquid quenched. turnings may be taken from a test specimen. The chemical
4.5.4 Tempering Temperature—The forgings shall be tem- composition thus determined shall not vary from the require-
pered to develop the specified properties. The final tempering ments specified in Table 1 more than the amounts prescribed in
temperature for Class 1 to 6 and 11 through 14 shall be not less Table 2.
than 1100°F (593°C), and for Class 10 not less than 1200°F 5.3 Test Methods of Analysis—Test Methods E 30 shall be
(649°C). The forgings shall be cooled under suitable conditions used for referee purposes.
from the tempering temperature.
6. Mechanical Properties
4.5.5 Stress Relief—Unless otherwise specified by the pur-
chaser, the forgings shall be stress relieved after machining 6.1 Tension Test—The material shall conform to the require-
(see 4.6.2) by heating slowly to a temperature within 100°F ment for tensile properties prescribed in Table 3 when tested in
(56°C) below the final tempering temperature but in no case accordance with Test Methods and Definitions A 370. Tension
below 1025°F (552°C) for Classes 1 to 6 and 11 through 14 and test specimens shall be the standard round, ⁄2 -in. (12.7-mm)
1150°F (621°C) for Class 10. They shall be held for a sufficient diameter, 2-in. (50.8-mm) gage length as shown in Test
length of time and then cooled under suitable conditions. This Methods and Definitions A 370. The yield strength prescribed
stress-relief temperature may be omitted provided the metal in Table 3 shall be determined by the 0.2 % offset method of
removed in accordance with 4.6.2, excluding test metal, does Test Methods and Definitions A 370. The offset shall be 0.2 %
not exceed ⁄16 in. (4.8 mm) on any surface. unless 0.02 % is specified in the ordering information.
TABLE 1 Chemical Requirements
Composition, %
Classes 1 to 6, Class 10 Classes 11 to 13, Class 14
incl incl
A
Carbon 0.28 max 0.27–0.37 0.38–0.43 0.45 max
Manganese 0.70 max 0.70–1.00 0.60–1.00 0.60–1.00
Phosphorus 0.012 max 0.012 max 0.012 max 0.012 max
Sulfur 0.015 max 0.015 max 0.015 max 0.015 max
B
Silicon 0.15–0.35 0.20 min 0.15–0.35 0.15–0.35
Nickel 2.00–4.00 0.50 max 0.50 max 1.65–3.50
Chromium 0.75–2.00 0.85–1.25 0.80–1.10 0.50–1.25
Molybdenum 0.20–0.70 1.00–1.50 0.15 min 0.20 min
Vanadium 0.05 min 0.20–0.30 0.06 max optional
CCCC
Antimony
A
0.35 % C max for Classes 4 and 5; 0.40 % C, max, for Class 6.
B
When vacuum deoxidation is specified, silicon content shall be 0.10 max.
C
To be reported for information only.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
A 471 – 94 (1999)
TABLE 2 Permissible Variations in Product Analysis
NOTE—Product cross-sectional area is defined as either:
(a) maximum cross-sectional area of rough machined forging (excluding boring),
(b) maximum cross-sectional area of the unmachined forging, or
(c) maximum cross-sectional area of the billet, bloom, or slab.
Area taken at right angles to the axis of the original ingot or billet
Permissible Variation Over the Specified Maximum Limit or
Under the Specified Minimum Limit, %
Up to and Over 100 Over 200 Over 400 Over 800 Over 1600
Unit or Maximum Specified
Element 2 2 2 2
including to 200 in. to 400 in. to 800 in. to 1600 in.
Range, %
2 2
100 in. (645 to (1290 to (2580 to in. (5160 (10 320
2 2 2 2 2
(645 cm ) 1290 cm ), 2580 cm ), 5160 cm ), to 10 320 cm )
incl incl incl cm ), incl
Carbon . . . 0.03 0.04 0.04 0.05 0.06 0.06
Manganese up to and including 0.90 0.03 0.04 0.05 0.06 0.07 0.08
0.91 and over 0.06 0.06 0.07 0.08 0.08 0.09
Phosphorus . . . 0.008 0.008 0.010 0.010 0.015 0.015
Sulfur . . . 0.005 0.005 0.005 0.005 0.006 0.006
Silicon . . . 0.02 0.03 0.04 0.04 0.05 0.06
Nickel up to and including 1.00 0.03 0.03 0.03 0.03 0.03 0.03
1.01 to 2.00, incl 0.05 0.05 0.05 0.05 0.05 0.05
2.01 and over 0.07 0.07 0.07 0.07 0.07 0.07
Chromium up to and including 0.90 0.03 0.04 0.04 0.05 0.05 0.06
0.91 and over 0.05 0.06 0.06 0.07 0.07 0.08
Molybdenum up to and including 0.20 0.01 0.02 0.02 0.02 0.03 0.03
0.21 to 0.40, incl 0.02 0.03 0.03 0.03 0.04 0.04
0.41 to 1.15, incl 0.03 0.04 0.05 0.06 0.07 0.08
1.16 and over 0.05 0.06 0.08 0.10 0.12 0.12
Vanadium up to and including 0.10 0.01 0.01 0.01 0.01 0.01 0.01
0.11 to 0.25, incl 0.02 0.02 0.02 0.02 0.02 0.02
0.26 and over 0.03 0.03 0.03 0.03 0.03 0.03
TABLE 3 Tensile and Charpy Impact Requirements
Class 1 Class 2 Class 3 Class 4 Class 5 Class 6
Tensile strength, min, ksi (MPa) 100 105 110 120 130 140
(690) (725) (760) 830) (900) (965)
Yield strength, ksi (MPa)
0.2 % offset 80–100 90–110 100–120 110–130 120–140 130–150
(550–690) (620–760) (690–825) (760–895) (825–965) (895–1035)
0.02 % offset 75–95 85–105 95–115 105–125 115–135 125–145
(520–655) (585–725) (655–790) (725–860) (790–930) (860–1000)
Elongation in 2 in. or 50 mm, min, % 20 19 18 17 16 15
Reduction of area, min, % 50 50 47 45 43 43
Charpy V-notch impact, room temperature, ft·lb, min 50 50 45 45 40 40
Transition temperature, FATT,°F,max 0000 10 10
Brinell hardness number . . . . . . . . . . . . . . . . . .
Class 10 Class 11 Class 12 Class 13 Class 14
Tensile strength, min, ksi (MPa) 105 100 110 125 125
(725) (690) (760) (860) (860)
Yield strength, ksi (MPa)
0.2 % offset 90–105 . . . . . . . .
... ... ...
(620–725) . . . . . . . . . . . .
0.02 % offset 85–100 75–95 85–105 105–125 105–125
(585–690) (515–655) (585–725) (725–860) (725–860)
Elongation in 2 in. or 50 mm, min, % 15 20.0 18.0 16.0 18.0
Reduction of area, min, % 30 50.0 48.0 45.0 45.0
Charpy V-notch impact, room temperature, ft·lb, min 10 15 (20) 15 (20) 15 (20) 15 (20)
AAAA
Transition temperature, FATT , °F, max 200
Brinell hardness number . . . 207–255 229–269 255–302 255–302
A
Not required.
6.2 Impact Test—The material shall conform to the require- 6.3 Hardness—Forgings made from Classes 11 to 14 and
ments for impact (both transition-temperature and room- subjected to group testing in accordance with 6.4.1 shall
temperature impact value) as prescribed in Table 3. The impact conform to the Brinell hardness requirements prescribed in
tests shall be performed in accordance with Test Methods and Table 3 when tested in accordance with Test Methods and
Definitions A 370 using standard full-size specimens. Definitions A 370.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
A 471 – 94 (1999)
6.4 Location and Number of Tests—Classes 1 through 10 10.1.2 Room temperature impact values lower than the
tension and impact test specimen shall be identified and taken minimum specified, but not less than 80 % of the minimum
from the locations as specified by the purchaser and agreed to shall be cause for retest. In this event, two additional adjacent
by the producer. One tension test and a transition-temperature bars shall be broken to represent each failed bar. Both
determination, including room-temperature impact strength specimens shall have an impact strength a
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