ASTM A646/A646M-06(2016)
(Specification)Standard Specification for Premium Quality Alloy Steel Blooms and Billets for Aircraft and Aerospace Forgings
Standard Specification for Premium Quality Alloy Steel Blooms and Billets for Aircraft and Aerospace Forgings
ABSTRACT
This specification deals with the standard requirements for premium quality alloy steel semifinished rolled or forged blooms and billets for reforging into aircraft and aerospace critical parts such as landing-gear forgings. Covered here are three basic classifications of steel, namely: Class I, steel manufactured by vacuum-induction melting or consumable-electrode vacuum melting process; Class II, air-melted steel manufactured by electric-furnace vacuum degassing process; Class III, air-melted steel manufactured by electric-furnace ladle refining and vacuum degassing processes. Steel materials shall be heat-treated and hot-worked by either hot rolling or forging. Alloy steels shall be examined by heat and product analyses and hardenability tests, and shall conform to chemical composition and maximum annealed Brinell hardness requirements. Quality evaluation tests, such as macrotech, microcleanliness, and nondestructive ultrasonic (both immersion and contact examination) inspection, shall be performed as well.
SCOPE
1.1 This specification covers premium quality alloy steel semifinished rolled or forged blooms and billets for reforging into critical parts such as aircraft landing-gear forgings.
1.2 Blooms and billets, hereinafter referred to as blooms, are semifinished steel products, hot rolled or forged to approximate cross-sectional dimensions. Blooms may be square, round, hexagonal, octagonal, or rectangular in section. For the purposes of this specification, minimum bloom section size will be 16 in.2 [103 cm2].
1.3 This specification covers two basic classifications of steel:
1.3.1 Class I—Vacuum-induction melted or consumable-electrode vacuum melted, or other suitable processes which will satisfy the quality requirements of this specification.
1.3.2 Class II—Air-melted vacuum degassed.
1.3.3 Class III—Air melted electric furnace ladle refined and vacuum degassed.
1.4 The values stated in either inch-pound or SI (metric) units are to be regarded separately as standards. Within the text and tables, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.
1.5 Unless the order specifies the applicable “M” specification the material shall be furnished to the inch-pound units.
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Designation:A646/A646M −06 (Reapproved 2016)
Standard Specification for
Premium Quality Alloy Steel Blooms and Billets for Aircraft
and Aerospace Forgings
This standard is issued under the fixed designationA646/A646M; 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.
1. Scope* A388/A388M Practice for Ultrasonic Examination of Steel
Forgings
1.1 This specification covers premium quality alloy steel
A788/A788M Specification for Steel Forgings, General Re-
semifinished rolled or forged blooms and billets for reforging
quirements
into critical parts such as aircraft landing-gear forgings.
A604/A604M Practice for Macroetch Testing of Consum-
1.2 Blooms and billets, hereinafter referred to as blooms,
able Electrode Remelted Steel Bars and Billets
are semifinished steel products, hot rolled or forged to approxi-
E45 Test Methods for Determining the Inclusion Content of
mate cross-sectional dimensions. Blooms may be square,
Steel
round, hexagonal, octagonal, or rectangular in section. For the
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam
purposes of this specification, minimum bloom section size
Contact Testing
2 2
will be 16 in. [103 cm ].
E127 Practice for Fabrication and Control of Aluminum
Alloy Ultrasonic Standard Reference Blocks
1.3 This specification covers two basic classifications of
steel: E214 Practice for Immersed Ultrasonic Testing by the Re-
flection Method Using Pulsed Longitudinal Waves (With-
1.3.1 Class I—Vacuum-induction melted or consumable-
electrode vacuum melted, or other suitable processes which drawn 2007)
E381 Method of Macroetch Testing Steel Bars, Billets,
will satisfy the quality requirements of this specification.
1.3.2 Class II—Air-melted vacuum degassed. Blooms, and Forgings
1.3.3 Class III—Air melted electric furnace ladle refined
2.2 AMS Standards:
and vacuum degassed.
AMS 2300 Steel Cleanliness, Premium-Quality
AMS 2301 Steel Cleanliness, Aircraft-Quality
1.4 The values stated in either inch-pound or SI (metric)
AMS 2304 Steel Cleanliness, Special Aircraft-Quality
units are to be regarded separately as standards.Within the text
andtables,theSIunitsareshowninbrackets.Thevaluesstated
3. Terminology
in each system are not exact equivalents; therefore, each
system shall be used independently of the other. Combining
3.1 In addition to the terminology requirements of Specifi-
values from the two systems may result in nonconformance
cation A788/A788M, the following terms that are specific to
with the specification.
this specification apply:
1.5 Unless the order specifies the applicable “M” specifica-
3.2 Definitions:
tion the material shall be furnished to the inch-pound units.
3.2.1 air-melted vacuum-degassed steel—arc- or induction-
furnace-melted steel that is vacuum treated immediately prior
2. Referenced Documents
to or during the operation of pouring the ingot.
2.1 ASTM Standards:
3.2.2 consumable-electrode vacuum-remelted steel—metal
A255 Test Methods for Determining Hardenability of Steel
that has been remelted into a crucible in vacuum from single or
multiple electrodes.
3.2.3 electroslag-melted steel—metal that has been remelted
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
into a crucible from single or multiple electrodes utilizing an
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets. electrical discharge through molten slag as a source of heat.
Current edition approved March 1, 2016. Published April 2016. Originally
approved in 1971. Last previous edition approved in 2011 as A646/A646M – 06
(2011). DOI: 10.1520/A0646_A0646M-06R16.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM www.astm.org.
Standards volume information, refer to the standard’s Document Summary page on Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale,
the ASTM website. PA 15096, http://www.sae.org.
*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
A646/A646M−06 (2016)
3.2.3.1 Discussion—For the purposes of this specification processes such as electroslag or electron-beam melting may be
the parent heat from which any electrode for remelting by the considered acceptable.
electroslag process has been produced shall have been either
5.1.1.2 Class II material shall be manufactured by an
melted under vacuum or vacuum degassed immediately prior
electric-furnace vacuum-degassed process.
to or during pouring of the heat.
5.1.1.3 Class III material shall be manufactured by the
electric furnace process with ladle refining and vacuum degas-
3.2.4 vacuum induction melted steel—metal that has been
melted, refined, and poured from an induction furnace operat- sing.
ing under vacuum.
5.2 Hot-Working Procedure:
5.2.1 Blooms may be either hot rolled or forged.
4. Ordering Information and General Requirements
5.2.2 Blooms having cross-sectional areas ranging from 16
4.1 Material supplied to this specification shall conform to
2 2
to 225 in. [100 to 1450 cm ] when made from air-melt ingots
the requirements of Specification A788/A788M, which out-
shall have at least 2 to 1 reduction of area from ingot to bloom.
lines additional ordering information, manufacturing
2 2
On blooms exceeding 225 in. [1450 cm ] forging reduction
requirements, testing and retesting methods and procedures,
requirements shall be by agreement. Ingot-to-final forging
marking, certification, product analysis variations, and addi-
reduction is not included in this requirement.
tional supplementary requirements.
5.3 Heat Treatment:
4.1.1 If the requirements of this specification are in conflict
with the requirements of Specification A788/A788M, the
5.3.1 Unless otherwise specified all material purchased to
requirements of this specification shall prevail. this specification will be furnished in the as forged or rolled
(untreated)condition.Inthisconditionsomegradesmaynotbe
4.2 In addition to the ordering requirements of Specification
soft enough for cold sawing, and may be prone to cracking.
A788/A788M, the following information should be supplied
5.3.2 When specified, the material may be ordered annealed
by the purchaser:
or normalized and tempered to a maximum Brinell Hardness,
4.2.1 Class designation (see 1.3),
as specified in Table 2 or by agreement.
4.2.2 Quality level (Table 2), grade designation (Table 1), or
5.3.3 Material shall be furnished in condition to withstand,
detailed chemistry for nonstandard grades,
for an indefinite time, exposure to all climatic conditions
4.2.3 Desired billet or bloom size,
withoutdevelopinganyexternalorinternalcracks.Themethod
4.2.4 Weight or quantity and length,
of cooling after hot working or of heat treatment before
4.2.5 Minimum forging reduction required if ordered size
2 2
exceeds 225 in. [1450 cm ] (see 5.2.2), shipment shall be optional with the manufacturer, who shall be
responsible (in the same manner as for discontinuities dis-
4.2.6 Annealing, if required (see 5.3.2),
4.2.7 Macroetch standards of acceptance (see 7.1), closed after delivery) for cracks which may develop before
material is subjected to reheating. When a specific heat
4.2.8 Microcleanliness standards of acceptance (see 7.2),
4.2.9 Specific ultrasonic examination requirements, such as treatment or conditioning of material is specified by the
purchaser, the manufacturer shall be responsible only for
transducer type and size, whether contact or immersion
carrying out those specific operations and not for any cracking
preferred, level of reportable discontinuities and any special
that may subsequently develop.
surface finish requirements.
4.2.10 Hardenability standards of acceptance (see 8.1), and
6. Chemical Requirements
4.2.11 Any supplementary requirements desired.
6.1 General Requirements:
5. Manufacture
6.1.1 Table 1 lists standard grades of alloy steel that are
5.1 Melting Practice:
currently produced in premium quality; however, it is not the
5.1.1 The steel making provisions of Specification A788/
intent of this specification to restrict application only to the
A788M shall apply, except for the following modifications;
materials listed in Table 1.
5.1.1.1 Class I material shall be manufactured by the
6.1.2 When a standard grade is ordered, the analysis shall
vacuum-induction-melting process or by the consumable-
conform to the requirements as to chemical composition
electrode vacuum-melting (VAR) process. By agreement other
prescribed in Table 1 for the ordered grade.
6.1.3 The steel, when ordered to other than a standard
analysis, shall conform to the requirements of the order.
TABLE 1 Maximum Permissible Discontinuities in Ultrasonic
6.2 Heat Analysis:
Examination
6.2.1 The heat analysis obtained from sampling in accor-
Response,
in. [mm]
Quality Stringers, dance with Specification A788/A788M shall comply with
Level Length in. [mm]
Single Multiple
Table 1 for standard grades, or to the requirements of the order.
Discontinuities Discontinuities
3 2 2 1 6.3 Product Analysis:
AA ⁄64 [1.0] ⁄64 [0.8] ⁄64 – ⁄2 [1.0–12.0]
5 3 3
A ⁄64 [2.0] ⁄64 [1.0] ⁄64 –1 [1.0–25]
6.3.1 The purchaser may use the product analysis provision
8 5 5
B ⁄64 [3.0] ⁄64 [2.0] ⁄64 –1 [2.0–25]
of Specification A788/A788M to obtain a product analysis
12 8 8
C ⁄64 [5.0] ⁄64 [3.0] ⁄64 –1 [3.0–25]
from a billet or bloom representing each heat or multiple heat.
A646/A646M−06 (2016)
A
TABLE 2 Chemical and Hardness Requirements
Composition, %
Grade Maximum
Proprietary
No. Manga- Phos- Chro- Molyb- Vana- Annealed
Name or Carbon Sulfur Silicon Nickel Others
nese phorus mium denum dium Brinell
Grade
Hardness
3310 1 0.08–0.13 0.45–0.60 0.015max 0.012 max 0.20–0.35 3.25–3.75 1.40–1.75 . . . . . . . . . 262
9310 2 0.08–0.13 0.45–0.65 0.015 max 0.012 max 0.20–0.35 3.00–3.50 1.00–1.40 0.08–0.15 . . . . . . 262
4620 3 0.17–0.22 0.45–0.65 0.015 max 0.012 max 0.20–0.35 1.65–2.00 . . . 0.20–0.30 . . . . . . 229
8620 4 0.18–0.23 0.70–0.90 0.015max 0.012 max 0.20–0.35 0.40–0.70 0.40–0.60 0.15–0.25 . . . . . . 229
4330 Mod. 5 0.28–0.33 0.75–1.00 0.015 max 0.012 max 0.20–0.35 1.65–2.00 0.70–0.95 0.35–0.50 0.05–0.10 . . . 285
4335 Mod. 6 0.33–0.38 0.60–0.90 0.015 max 0.012 max 0.40–0.60 1.65–2.00 0.65–0.90 0.30–0.40 0.17–0.23 . . . 285
4340 7 0.38–0.43 0.65–0.85 0.015 max 0.012 max 0.20–0.35 1.65–2.00 0.70–0.90 0.20–0.30 . . . . . . 285
300 M 8 0.38–0.43 0.65–0.90 0.012 max 0.012 max 1.45–1.80 1.65–2.00 0.70–0.95 0.35–0.45 0.05–0.10 . . . 285
D6AC 9 0.45–0.50 0.60–0.90 0.010 max 0.010 max 0.15–0.30 0.40–0.70 0.90–1.20 0.90–1.10 0.08–0.15 . . . 285
H-11 10 0.38–0.43 0.20–0.40 0.015 max 0.015 max 0.80–1.00 . . . 4.75–5.25 1.20–1.40 0.40–0.60 . . . 235
4130 11 0.28–0.33 0.40–0.60 0.015 max 0.012 max 0.20–0.35 . . . 0.80–1.10 0.15–0.25 . . . . . . 229
4140 12 0.38–0.43 0.75–1.00 0.015 max 0.012 max 0.20–0.35 . . . 0.80–1.10 0.15–0.25 . . . . . . 235
98BV40 13 0.40–0.46 0.75–1.00 0.015 max 0.012 max 0.50–0.80 0.60–0.90 0.80–1.05 0.45–0.60 0.01–0.06 0.0005 min, 285
Boron
6150 14 0.48–0.53 0.70–0.90 0.015 max 0.012 max 0.20–0.35 . . . 0.80–1.10 . . . 0.15 min . . . 235
52100 15 0.98–1.10 0.25–0.45 0.015 max 0.010 max 0.20–0.35 . . . 1.30–1.60 . . . . . . . . . 302
HP 9-4-20 16 0.17–0.23 0.20–0.40 0.010 max 0.010 max 0.10 max 8.5–9.5 0.65–0.85 0.90–1.10 0.06–0.12 Co 4.25–4.75 341
HP 9-4-30 17 0.29–0.34 0.10–0.35 0.010 max 0.010 max 0.10 max 7.0–8.0 0.90–1.10 0.90–1.10 0.06–0.12 Co 4.25–4.75 341
Marage 18 0.03 max 0.10 max 0.010 max 0.010 max 0.10 max 17.0–19.0 . . . 3.0–3.50 . . . Co 8.0–9.0 321
200 Ti 0.10–0.25
Al 0.05–0.15
B, Zr, Ca added
Marage 19 0.03 max 0.10 max 0.010 max 0.010 max 0.10 max 17.0–19.0 . . . 4.6–5.2 . . . Co 7.0–8.5 321
250 Ti 0.30–0.50
Al 0.05–0.15
B, Zr, Ca added
Marage 20 0.03 max 0.10 max 0.010 max 0.010 max 0.10 max 18.0–19.0 . . . 4.7–5.2 . . . Co 8.5–9.5 321
300 Ti 0.50–0.80
Al 0.05–0.15
B, Zr, Ca added
Nit. 135 21 0.38–0.43 0.50–0.70 0.015 max 0.012 max 0.20–0.40 . . . 1.40–1.80 0.30–0.40 . . . Al 0.95–1.30 285
A
If any of the following elements are not specified, the following maximum limits shall apply: Nickel 0.35 %; Chromium 0.20 %; Molybdenum 0.06 %; Copper 0.35 %.
7. Quality Evaluation Tests 7.3.1.1 All material ordered to this specification shall be
subjected to ultrasonic examination. Inspection may be per-
7.1 Macroetch—Macroetch inspection shall be required for
formed by either the immersion or the contact method provid-
all material furnished to this specification. Samples represent-
ing that the manufacturer can ensure adequate resolution of the
ing the top and bottom of each ingot shall be examined.
applicable reference standards with the chosen method.
Macroetching shall be performed in accordance with Method
7.3.1.2 The usage of reference blocks containing flat-
E381 and Test Method A604/A604M, as applicable. Standards
bottomed holes for calibration is the preferred method for
of acceptance shall be specified by the purchaser in the order.
evaluation of discontinunity size up to billet cross-sectional
7.2 Microcleanliness—All material furnished to this speci-
dimensions of approximately 12 in. [300 mm]. With larger
fication shall be inspected for microcleanliness. At least one
sizes, it is recognized that reference block fabrication becomes
sample shall be removed from a location midway between the
difficult and in general a back reflection method of calibration
center and outside surface representing the top and bottom of
can be used as an alternative as referenced in 7.3.6.3.
the first and last ingots of each heat or from an ingot from each
7.3.2 Immersion Examination Procedure—This method is
plate for bottom poured ingots. For blooms produced from
recommendedformaterialwherethecross-sectionaldimension
continually cast material the samples shall represent the
to be inspected is less than approximately 8 in. [200 mm].
beginning and end of each strand produced from the heat. The
Material inspected by the immersion method shall be per-
specimens shall be prepared and rated by the procedure
formed in accordance with the procedure outlined in Practice
described in MethodAofTest Methods E45.The polished face
E214.
shall be longitudinal to the direction of maximum hot working.
All specimens shall be prepared and rated in accordance with
7.3.3 Contact Exami
...
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: A646/A646M − 06 (Reapproved 2011) A646/A646M − 06 (Reapproved 2016)
Standard Specification for
Premium Quality Alloy Steel Blooms and Billets for Aircraft
and Aerospace Forgings
This standard is issued under the fixed designation A646/A646M; 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.
1. Scope*
1.1 This specification covers premium quality alloy steel semifinished rolled or forged blooms and billets for reforging into
critical parts such as aircraft landing-gear forgings.
1.2 Blooms and billets, hereinafter referred to as blooms, are semifinished steel products, hot rolled or forged to approximate
cross-sectional dimensions. Blooms may be square, round, hexagonal, octagonal, or rectangular in section. For the purposes of this
2 2
specification, minimum bloom section size will be 16 in. [103 cm ].
1.3 This specification covers two basic classifications of steel:
1.3.1 Class I—Vacuum-induction melted or consumable-electrode vacuum melted, or other suitable processes which will satisfy
the quality requirements of this specification.
1.3.2 Class II—Air-melted vacuum degassed.
1.3.3 Class III—Air melted electric furnace ladle refined and vacuum degassed degassed.
1.4 The values stated in either inch-pound or SI (metric) units are to be regarded separately as standards. Within the text and
tables, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system shall
be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.
1.5 Unless the order specifies the applicable “M” specification the material shall be furnished to the inch-pound units.
2. Referenced Documents
2.1 ASTM Standards:
A255 Test Methods for Determining Hardenability of Steel
A388/A388M Practice for Ultrasonic Examination of Steel Forgings
A788/A788M Specification for Steel Forgings, General Requirements
A604A604/A604M Test Method Practice for Macroetch Testing of Consumable Electrode Remelted Steel Bars and Billets
E45 Test Methods for Determining the Inclusion Content of Steel
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam Contact Testing
E127 Practice for Fabrication and Control of Aluminum Alloy Ultrasonic Standard Reference Blocks
E214 Practice for Immersed Ultrasonic Testing by the Reflection Method Using Pulsed Longitudinal Waves (Withdrawn 2007)
E381 Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings
2.2 AMS Standards:
AMS 2300 Steel Cleanliness, Premium-Quality
AMS 2301 Steel Cleanliness, Aircraft-Quality
AMS 2304 Steel Cleanliness, Special Aircraft-Quality
3. Terminology
3.1 In addition to the terminology requirements of Specification A788/A788M, the following terms that are specific to this
specification apply:
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, 2011March 1, 2016. Published June 2011April 2016. Originally approved in 1971. Last previous edition approved in 20062011 as
A646/A646M – 06.A646/A646M – 06 (2011). DOI: 10.1520/A0646_A0646M-06R11. 10.1520/A0646_A0646M-06R16.
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.
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001,15096, http://www.sae.org.
*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
A646/A646M − 06 (2016)
3.2 Definitions:
3.2.1 air-melted vacuum-degassed steel—arc- or induction-furnace-melted steel that is vacuum treated immediately prior to or
during the operation of pouring the ingot.
3.2.2 consumable-electrode vacuum-remelted steel—metal that has been remelted into a crucible in vacuum from single or
multiple electrodes.
3.2.3 electroslag-melted steel—metal that has been remelted into a crucible from single or multiple electrodes utilizing an
electrical discharge through molten slag as a source of heat.
3.2.3.1 Discussion—
For the purposes of this specification the parent heat from which any electrode for remelting by the electroslag process has been
produced shall have been either melted under vacuum or vacuum degassed immediately prior to or during pouring of the heat.
3.2.4 vacuum induction melted steel—metal that has been melted, refined, and poured from an induction furnace operating under
vacuum.
4. Ordering Information and General Requirements
4.1 Material supplied to this specification shall conform to the requirements of Specification A788/A788M, which outlines
additional ordering information, manufacturing requirements, testing and retesting methods and procedures, marking, certification,
product analysis variations, and additional supplementary requirements.
4.1.1 If the requirements of this specification are in conflict with the requirements of Specification A788/A788M, the
requirements of this specification shall prevail.
4.2 In addition to the ordering requirements of Specification A788/A788M, the following information should be supplied by the
purchaser:
4.2.1 Class designation (see 1.3),
4.2.2 Quality level (Table 2), grade designation (Table 1), or detailed chemistry for nonstandard grades,
4.2.3 Desired billet or bloom size,
4.2.4 Weight or quantity and length,
2 2
4.2.5 Minimum forging reduction required if ordered size exceeds 225 in. [1450 cm ] (see 5.2.2),
4.2.6 Annealing, if required (see 5.3.2),
4.2.7 Macroetch standards of acceptance (see 7.1),
4.2.8 Microcleanliness standards of acceptance (see 7.2),
4.2.9 Specific ultrasonic examination requirements, such as transducer type and size, whether contact or immersion preferred,
level of reportable discontinuities and any special surface finish requirements.
4.2.10 Hardenability standards of acceptance (see 8.1), and
4.2.11 Any supplementary requirements desired.
5. Manufacture
5.1 Melting Practice:
5.1.1 The steel making provisions of Specification A788/A788M shall apply, except for the following modifications;
5.1.1.1 Class I material shall be manufactured by the vacuum-induction-melting process or by the consumable-electrode
vacuum-melting (VAR) process. By agreement other processes such as electroslag or electron-beam melting may be considered
acceptable.
5.1.1.2 Class II material shall be manufactured by an electric-furnace vacuum-degassed process.
5.1.1.3 Class III material shall be manufactured by the electric furnace process with ladle refining and vacuum degassing.
5.2 Hot-Working Procedure:
5.2.1 Blooms may be either hot rolled or forged.
TABLE 1 Maximum Permissible Discontinuities in Ultrasonic
Examination
Quality Response, Stringers,
Level in. [mm] Length in. [mm]
Single Single Multiple
Discontinuities Discontinuities Discontinuities
3 2 2 1
AA ⁄64 [1.0] ⁄64 [0.8] ⁄64 – ⁄2 [1.0–12.0]
5 3 3
A ⁄64 [2.0] ⁄64 [1.0] ⁄64 –1 [1.0–25]
8 5 5
B ⁄64 [3.0] ⁄64 [2.0] ⁄64 –1 [2.0–25]
12 8 8
C ⁄64 [5.0] ⁄64 [3.0] ⁄64 –1 [3.0–25]
A646/A646M − 06 (2016)
A
TABLE 2 Chemical and Hardness Requirements
Composition, %
Proprie- Grade Carbon Manga- Phos- Sulfur Silicon Nickel Chro- Molyb- Vana- Others Maximum
Proprietary No. nese phorus mium denum dium Annealed
tary Name Brinell
or Hardness
Grade
3310 1 0.08–0.13 0.45–0.60 0.015max 0.012 max 0.20–0.35 3.25–3.75 1.40–1.75 . . . . . . . . . 262
9310 2 0.08–0.13 0.45–0.65 0.015 max 0.012 max 0.20–0.35 3.00–3.50 1.00–1.40 0.08–0.15 . . . . . . 262
4620 3 0.17–0.22 0.45–0.65 0.015 max 0.012 max 0.20–0.35 1.65–2.00 . . . 0.20–0.30 . . . . . . 229
8620 4 0.18–0.23 0.70–0.90 0.015max 0.012 max 0.20–0.35 0.40–0.70 0.40–0.60 0.15–0.25 . . . . . . 229
4330 Mod. 5 0.28–0.33 0.75–1.00 0.015 max 0.012 max 0.20–0.35 1.65–2.00 0.70–0.95 0.35–0.50 0.05–0.10 . . . 285
4335 Mod. 6 0.33–0.38 0.60–0.90 0.015 max 0.012 max 0.40–0.60 1.65–2.00 0.65–0.90 0.30–0.40 0.17–0.23 . . . 285
4340 7 0.38–0.43 0.65–0.85 0.015 max 0.012 max 0.20–0.35 1.65–2.00 0.70–0.90 0.20–0.30 . . . . . . 285
300 M 8 0.38–0.43 0.65–0.90 0.012 max 0.012 max 1.45–1.80 1.65–2.00 0.70–0.95 0.35–0.45 0.05–0.10 . . . 285
D6AC 9 0.45–0.50 0.60–0.90 0.010 max 0.010 max 0.15–0.30 0.40–0.70 0.90–1.20 0.90–1.10 0.08–0.15 . . . 285
H-11 10 0.38–0.43 0.20–0.40 0.015 max 0.015 max 0.80–1.00 . . . 4.75–5.25 1.20–1.40 0.40–0.60 . . . 235
4130 11 0.28–0.33 0.40–0.60 0.015 max 0.012 max 0.20–0.35 . . . 0.80–1.10 0.15–0.25 . . . . . . 229
4140 12 0.38–0.43 0.75–1.00 0.015 max 0.012 max 0.20–0.35 . . . 0.80–1.10 0.15–0.25 . . . . . . 235
98BV40 13 0.40–0.46 0.75–1.00 0.015 max 0.012 max 0.50–0.80 0.60–0.90 0.80–1.05 0.45–0.60 0.01–0.06 0.0005 min, 285
Boron
6150 14 0.48–0.53 0.70–0.90 0.015 max 0.012 max 0.20–0.35 . . . 0.80–1.10 . . . 0.15 min . . . 235
52100 15 0.98–1.10 0.25–0.45 0.015 max 0.010 max 0.20–0.35 . . . 1.30–1.60 . . . . . . . . . 302
HP 9-4-20 16 0.17–0.23 0.20–0.40 0.010 max 0.010 max 0.10 max 8.5–9.5 0.65–0.85 0.90–1.10 0.06–0.12 Co 4.25–4.75 341
HP 9-4-30 17 0.29–0.34 0.10–0.35 0.010 max 0.010 max 0.10 max 7.0–8.0 0.90–1.10 0.90–1.10 0.06–0.12 Co 4.25–4.75 341
Marage 18 0.03 max 0.10 max 0.010 max 0.010 max 0.10 max 17.0–19.0 . . . 3.0–3.50 . . . Co 8.0–9.0 321
200 Ti 0.10–0.25
Al 0.05–0.15
B, Zr, Ca added
Marage 19 0.03 max 0.10 max 0.010 max 0.010 max 0.10 max 17.0–19.0 . . . 4.6–5.2 . . . Co 7.0–8.5 321
250 Ti 0.30–0.50
Al 0.05–0.15
B, Zr, Ca added
Marage 20 0.03 max 0.10 max 0.010 max 0.010 max 0.10 max 18.0–19.0 . . . 4.7–5.2 . . . Co 8.5–9.5 321
300 Ti 0.50–0.80
Al 0.05–0.15
B, Zr, Ca added
Nit. 135 21 0.38–0.43 0.50–0.70 0.015 max 0.012 max 0.20–0.40 . . . 1.40–1.80 0.30–0.40 . . . Al 0.95–1.30 285
A
If any of the following elements are not specified, the following maximum limits shall apply: Nickel 0.35 %; Chromium 0.20 %; Molybdenum 0.06 %; Copper 0.35 %.
2 2
5.2.2 Blooms having cross-sectional areas ranging from 16 to 225 in. [100 to 1450 cm ] when made from air-melt ingots shall
2 2
have at least 2 to 1 reduction of area from ingot to bloom. On blooms exceeding 225 in. [1450 cm ] forging reduction requirements
shall be by agreement. Ingot-to-final forging reduction is not included in this requirement.
5.3 Heat Treatment:
5.3.1 Unless otherwise specified all material purchased to this specification will be furnished in the as forged or rolled
(untreated) condition. In this condition some grades may not be soft enough for cold sawing, and may be prone to cracking.
5.3.2 When specified, the material may be ordered annealed or normalized and tempered to a maximum Brinell Hardness, as
specified in Table 2 or by agreement.
5.3.3 Material shall be furnished in condition to withstand, for an indefinite time, exposure to all climatic conditions without
developing any external or internal cracks. The method of cooling after hot working or of heat treatment before shipment shall be
optional with the manufacturer, who shall be responsible (in the same manner as for discontinuities disclosed after delivery) for
cracks which may develop before material is subjected to reheating. When a specific heat treatment or conditioning of material
is specified by the purchaser, the manufacturer shall be responsible only for carrying out those specific operations and not for any
cracking that may subsequently develop.
6. Chemical Requirements
6.1 General Requirements:
6.1.1 Table 1 lists standard grades of alloy steel that are currently produced in premium quality; however, it is not the intent
of this specification to restrict application only to the materials listed in Table 1.
6.1.2 When a standard grade is ordered, the analysis shall conform to the requirements as to chemical composition prescribed
in Table 1 for the ordered grade.
6.1.3 The steel, when ordered to other than a standard analysis, shall conform to the requirements of the order.
6.2 Heat Analysis:
6.2.1 The heat analysis obtained from sampling in accordance with Specification A788/A788M shall comply with Table 1 for
standard grades, or to the requirements of the order.
A646/A646M − 06 (2016)
6.3 Product Analysis:
6.3.1 The purchaser may use the product analysis provision of Specification A788/A788M to obtain a product analysis from a
billet or bloom representing each heat or multiple heat.
7. Quality Evaluation Tests
7.1 Macroetch—Macroetch inspection shall be required for all material furnished to this specification. Samples representing the
top and bottom of each ingot shall be examined. Macroetching shall be performed in accordance with Method E381 and Test
Method A604A604/A604M, as applicable. Standards of acceptance shall be specified by the purchaser in the order.
7.2 Microcleanliness—All material furnished to this specification shall be inspected for microcleanliness. At least one sample
shall be removed from a location midway between the center and outside surface representing the top and bottom of the first and
last ingots of each heat or from an ingot from each plate for bottom poured ingots. For blooms produced from continually cast
material the samples shall represent the beginning and end of each strand produced from the heat. The specimens shall be prepared
and rated by the procedure described in Method A of Test Methods E45. The polished face shall be longitudinal to the direction
of maximum hot working. All specimens shall be prepared and rated in accordance with Test Methods E45, using Method D
(Modified JK Chart) for Class I steel and Method A (JK Chart) for Classrs II and III steel. Standards of acceptance shall be specified
by the purchaser in the order.
7.3 Nondestructive Testing, Ultrasonic Inspection:
7.3.1 General:
7.3.1.1 All material ordered to this specification shall be subjected to ultrasonic examination. Inspection may be performed by
either the immersion or the contact method providing that the manufacturer can ensure
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