ASTM A604/A604M-07(2022)
(Practice)Standard Practice for Macroetch Testing of Consumable Electrode Remelted Steel Bars and Billets
Standard Practice for Macroetch Testing of Consumable Electrode Remelted Steel Bars and Billets
SIGNIFICANCE AND USE
4.1 Macroetch testing, as described herein, is a method for examining and rating transverse sections of bars and billets to describe certain conditions of macro segregation which are often characteristic of consumable electrode remelted materials.
4.2 This practice is not intended to define major defects such as those described by Method E381.
SCOPE
1.1 This practice2 covers testing and inspection and is applicable to bars, billets, and blooms of carbon, alloy, and stainless steel which have been consumable electrode remelted.
1.2 For the purpose of this practice, the consumable electrode remelting process is defined as a steel refining method wherein single or multiple electrodes are remelted into a crucible producing an ingot which is superior to the original electrode by virtue of improved cleanliness or lower gas content or reduced chemical or nonmetallic segregation. See Appendix X1 and Appendix X2 for descriptions of applicable remelting processes.
1.3 This practice and the accompanying comparison macrographs3 are generally applicable to steel bar and billet sizes up to 225 in.2 [1450 cm2] in transverse cross section.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: A604/A604M − 07 (Reapproved 2022)
Standard Practice for
Macroetch Testing of Consumable Electrode Remelted Steel
Bars and Billets
This standard is issued under the fixed designationA604/A604M; 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 Development of International Standards, Guides and Recom-
2 mendations issued by the World Trade Organization Technical
1.1 This practice covers testing and inspection and is
Barriers to Trade (TBT) Committee.
applicable to bars, billets, and blooms of carbon, alloy, and
stainlesssteelwhichhavebeenconsumableelectroderemelted.
2. Referenced Documents
1.2 For the purpose of this practice, the consumable elec- 4
2.1 ASTM Standard:
trode remelting process is defined as a steel refining method
E381 Method of Macroetch Testing Steel Bars, Billets,
wherein single or multiple electrodes are remelted into a
Blooms, and Forgings
crucible producing an ingot which is superior to the original
2.2 ASTM Adjunct:
electrode by virtue of improved cleanliness or lower gas
Adjunct to A604/A604M Practice for Macroetch Testing of
content or reduced chemical or nonmetallic segregation. See
Consumable Electrode Remelted Steel Bars and Billets
Appendix X1 and Appendix X2 for descriptions of applicable
remelting processes.
3. Description of Macroetch Testing
1.3 This practice and the accompanying comparison mac-
3.1 This practice employs the action of an acid or other
rographs are generally applicable to steel bar and billet sizes
corrosive agent to develop the characteristics of a suitably
2 2
up to 225 in. [1450 cm ] in transverse cross section.
prepared specimen. After etching, the sections are compared
visually, or at a very low magnification, if necessary for
1.4 The values stated in either SI units or inch-pound units
clarification of conditions, to standard plates describing the
are to be regarded separately as standard. The values stated in
various conditions which may be found. Materials react differ-
each system are not necessarily exact equivalents; therefore, to
ently to etching reagents because of variations in chemical
ensure conformance with the standard, each system shall be
composition,methodofmanufacture,heattreatment,andmany
used independently of the other, and values from the two
other variables.
systems shall not be combined.
1.5 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 Macroetch testing, as described herein, is a method for
responsibility of the user of this standard to establish appro-
examining and rating transverse sections of bars and billets to
priate safety, health, and environmental practices and deter-
describe certain conditions of macro segregation which are
mine the applicability of regulatory limitations prior to use.
often characteristic of consumable electrode remelted materi-
1.6 This international standard was developed in accor-
als.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
4.2 This practice is not intended to define major defects
such as those described by Method E381.
This practice is under the jurisdiction of ASTM Committee A01 on Steel,
5. Application
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets.
5.1 When material is furnished subject to macroetch testing
Current edition approved March 1, 2022. Published March 2022. Originally
and inspection under this practice, the manufacturer and
approved in 1970. Last previous edition approved in 2017 as A604/
purchaser should be in agreement concerning the following:
A604M – 07(2017). DOI: 10.1520/A0604_A0604M-07R22.
ASTM CommitteeA01 gratefully acknowledges the help of theAISI Commit-
tee on General Metallurgy in preparing the appendix, assembling the macroetch
photographs, and assisting with the text of this practice. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
A complete set of the 20 macrographs on glossy paper available from ASTM contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
International Headquarters. Order Adjunct No. ADJA0604. Original adjunct pro- Standards volume information, refer to the standard’s Document Summary page on
duced in 1985. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A604/A604M − 07 (2022)
5.1.1 The stage of manufacture at which the test shall be 18 % chromium, 8 % nickel type and higher alloy types. This
conducted, reagent is used at room temperature.
5.1.2 The number and location of the sections to be tested,
NOTE 1—The reagents in 7.2.1, 7.2.2, and 7.2.3 should be used under
5.1.3 The condition and preparation of the surface to be
ventilating hoods or with some provision to remove the corrosive fumes.
macroetched,
7.2.4 Nitric Acid—This etchant consists of 5 % HNO
5.1.4 The etching reagent, temperature and time of etching,
solution in alcohol or water, and is generally used at room
or degree of etching including any special techniques which
temperature.Whenthisreagentisused,theetchdiskmusthave
must be used, and
a smooth surface.
5.1.5 The type and degree of conditions or combinations
thereof that shall be considered acceptable or subject to 8. Etching Containers
metallurgical review.
8.1 Macroetching must be done in containers that are
resistant to attack from the etching reagents. Caution must be
6. Sample Preparation
exerted to prevent the occurrence of electrolytic couples which
6.1 Unless otherwise specified, the test shall be performed
can cause uneven attacks and misleading results.
on specimens, usually ⁄4 to 1 in. [6 to 25 mm] thick, cut to
9. Preparation of Etched Surface and Examination
reveal a transverse surface.
9.1 Upon completion of etching, surfaces of disks should be
6.2 Disks for macroetch inspection may be removed from
cleaned by either chemical or mechanical methods that do not
billets by a variety of methods including torch cutting, sawing,
affect the macroetch quality. Care should be taken to prevent
machining, or high-speed abrasive wheels. Adequate prepara-
rusting of the etched surface.
tion of the surface for macroetching must completely remove
the effects of torch cutting or high-speed abrasive wheels.
10. Interpretation of Conditions Found by Macroetching
6.3 Due to the nature of the conditions to be detected,
10.1 Four distinct classes of conditions are defined and
further surface preparation is usually required.
described under this practice:
10.1.1 Class 1: Freckles—Circular or near-circular dark
6.4 When such further preparation is performed, grinding,
etching areas generally enriched with carbides and carbide-
machining, or sanding should be carried out in such a manner
forming elements.
as not to mask the structure.
10.1.2 Class2:WhiteSpots—Light etching areas, having no
6.5 The surface of the disk to be etched must be free of dirt,
definitive configuration or orientation which are generally
grease, or other foreign material which might impair the result
reduced in carbide or carbide-forming elements.
of the test.
10.1.3 Class 3: Radial Segregation—Radially or spirally
oriented dark etching elongated areas occurring most fre-
7. Etching Reagents
quently at mid-radius which are generally carbide enriched.
7.1 The etching response and appearance is dependent upon
This condition may be easily confused with freckles in some
the type and temperature of the etching reagent and the time of
materials.
immersion. These details must be established by agreement
10.1.4 Class4:RingPattern—One or more concentric rings
between manufacturer and purchaser.
evidenced by a differential in etch texture associated with
7.2 For illustrative purposes some of the commonly used minor composition gradients and ingot solidification.
etching reagents are as follows:
10.2 Macroetch photographs show examples of each of the
7.2.1 Hydrochloric Acid—A solution of 1 part commercial
conditions revealed by macroetch testing, with five degrees of
concentrated hydrochloric acid (HCl, sp gr 1.19) and 1 part
severity, identified as A, B, C, D, and E for each condition.
water is more generally used than any other macroetching
Degree A exhibits the minimum occurrence of each condition
reagent. This solution may be heated without significant
detectable by visual examination of the etched surface, while
change in concentration, and may be reused if it has not
degrees B, C, D, and E represent increasing severity of
become excessively contaminated or weakened. Etching is
occurrence.
generally done with the solution at a temperature of approxi-
10.3 For each condition, or combination of conditions,
mately 160 °F [70 °C].
ratings shall be obtained by comparing each macroetched
7.2.2 Hydrochloric Acid-Sulfuric Acid Mixture—A mixture
section with the standard photographs. Bar or billet sections to
containing 50 % wa
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