ASTM A561-08(2020)
(Practice)Standard Practice for Macroetch Testing of Tool Steel Bars
Standard Practice for Macroetch Testing of Tool Steel Bars
ABSTRACT
This practice covers macroetch testing used for evaluating the quality of tool steel bars. This test shall be used as a quality control and inspection test to reveal by deep acid etching, the macrostructure in specimens cut from bars and to show the presence, absence, and severity of the following internal, surface, or subsurface conditions: pipe, bursts, carbide or alloy segregation, nonmetallic inclusion concentrations, porosity, cracks or thermal flakes, seams, laps, ingot corner segregation, pinholes, foreign material, and ingot pattern. Macroetching may be performed in a vessel of borosilicate glass, porcelain, corrosion-resistant metals, or some other acid resisting material. The etching reagent, specimen sampling, specimen preparation, and testing procedure including etching temperature, etching time, and macroetching technique are detailed.
SCOPE
1.1 This practice for macroetch testing has been found to be a useful and reliable method for evaluating the quality of tool steel bars. It is used as a quality control and inspection test to reveal by deep acid etching the macrostructure in specimens cut from bars and to show the presence of such conditions as pipe, cracks, porosity, segregation, or foreign material. The etched surface is generally examined visually, but magnification up to about 10× is occasionally employed.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3 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
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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: A561 − 08 (Reapproved 2020)
Standard Practice for
Macroetch Testing of Tool Steel Bars
This standard is issued under the fixed designation A561; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 and the fumes are corrosive and irritating, although nontoxic.
The solution may be reused within limits. With use, the
1.1 This practice for macroetch testing has been found to be
concentration of dissolved iron and other metals increases and
a useful and reliable method for evaluating the quality of tool
the acidity of the solution decreases retarding the etching
steel bars. It is used as a quality control and inspection test to
action.Spentsolutionshallbereplacedwithfreshsolution,not
reveal by deep acid etching the macrostructure in specimens
replenished with concentrated acid.
cut from bars and to show the presence of such conditions as
pipe, cracks, porosity, segregation, or foreign material. The
5. Sampling
etched surface is generally examined visually, but magnifica-
tion up to about 10× is occasionally employed.
5.1 The selection of specimens for macroetch testing must
be done with care for interpretations to be of value.
1.2 The values stated in inch-pound units are to be regarded
5.1.1 Specimens are usually cut from hot-rolled annealed
as standard. The values given in parentheses are mathematical
bars, but may be cut from machined or ground bars if the bars
conversions to SI units that are provided for information only
are to be finish machined or ground.
and are not considered standard.
5.1.2 Thespecimenshouldbelocatedatasufficientdistance
1.3 This international standard was developed in accor-
from the end of the bar to avoid end effects.
dance with internationally recognized principles on standard-
1 1
5.1.3 For ease in handling, use specimens ⁄4 in. to ⁄2 in.
ization established in the Decision on Principles for the
(6.35 mm to 12.7 mm) thick.
Development of International Standards, Guides and Recom-
5.1.4 Cut specimens to expose a transverse section of the
mendations issued by the World Trade Organization Technical
bar; however, the test is occasionally performed on a longitu-
Barriers to Trade (TBT) Committee.
dinal section.
5.1.5 Specimens may be taken from one or both ends of a
2. Referenced Documents
bar. Each bar may be sampled, or a few typical specimens may
2.1 ASTM Adjuncts:
be tested as representative of a large number of bars.
Six Photomacrographs
6. Specimen Preparation
3. Apparatus
6.1 In all cutting and grinding operations on the specimen,
3.1 Etching Containers—Macroetching may be performed
care must be exercised to avoid heating the surface to an
in a vessel of borosilicate glass, porcelain, corrosion-resistant
excessively high temperature. Specimens are cut from bars by
metals, or some other acid-resisting material.
sawing, machining, abrasive wheel cutting, or other means.
4. Reagent
Cutting should be controlled to prevent smearing the cut face
and masking the structure.
4.1 Etching Reagent—A solution of equal volumes of con-
6.1.1 The“as-cut”surfaceofaspecimenmaybesufficiently
centrated hydrochloric acid (HCl, sp gr 1.19) and water is
smooth to reveal the defects for which the examination is
commonly used for macroetching tool steels. This solution
conducted. No additional surface preparation may then be
must be used under a ventilating hood because HCl is volatile
necessary.
6.1.2 Additional surface preparation may be required to
This practice is under the jurisdiction of ASTM Committee A01 on Steel,
remove cutting marks and to allow details to be revealed by
Stainless Steel and Related Alloysand is the direct responsibility of Subcommittee
etching. In such circumstances, machining, grinding, or pol-
A01.29 on Tool Steels.
Current edition approved March 1, 2020. Published March 2020. Originally
ishing may be necessary. Generally, the degree of surface
approvedin1966.Lastpreviouseditionapprovedin2014asA561–08(2014).DOI:
smoothness required is greater the finer the detail that must be
10.1520/A0561–08R20.
resolved. When the action of the etchant is drastic, a coarser
Available from ASTM International Headquarters. Order Adjunct No.
ADJA0561. Original adjunct produced in 1984. surface finish may be used.
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A561 − 08 (2020)
6.1.3 The surface must be free of adhering grease and oil. 8. Interpretation of Results
There should be no scale or oxide on the surface which will be
8.1 Examine the etched surface visually or at up to 10×
examined after etching.
magnification to determine its structure. Note the presence,
absence, and severity of the following conditions:
7. Procedure
8.1.1 Internal:
7.1 Temperature for Macroetching—Etching characteristics
8.1.1.1 Pip
...
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