ASTM E340-23

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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: E340 − 15 E340 − 23
Standard Practice for
Macroetching Metals and Alloys
This standard is issued under the fixed designation E340; 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
1.1 These procedures describe the methods of macroetching metals and alloys to reveal their macrostructure.
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 the International System (SI) units that are provided for information only and are not considered 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 healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.For specific warning statements, see 6.2, 7.1, 8.1.3, 8.2.1, 8.8.3, 8.10.1.1,
and 8.13.2.For specific warning statements, see 6.2, 7.1, 8.1.3, 8.2.1, 8.8.3, 8.10.1.1, and 8.13.2. It is further recommended to
review the guidance in Guide E2014.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
E3 Guide for Preparation of Metallographic Specimens
E381 Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings
E2014 Guide on Metallographic Laboratory Safety
3. Significance and Use
3.1 Applications of Macroetching:
3.1.1 Macroetching is used to reveal the heterogeneity of metals and alloys. Metallographic specimens and chemical analyses will
provide the necessary detailed information about specific localities, but they cannot give data about variation from one place to
another unless an inordinate number of specimens are taken.
3.1.2 Macroetching, on the other hand, will provide information on variations in (1) structure, such as grain size, flow lines,
columnar structure, dendrites, and so forth; (2) variations in chemical composition as evidenced by segregation, carbide and ferrite
This test method is under the jurisdiction of ASTM Committee E04 on Metallography and is the direct responsibility of Subcommittee E04.01 on Specimen Preparation.
Current edition approved June 1, 2015Nov. 15, 2023. Published July, 2015November 2023. Originally approved in 1968. Last previous edition approved in 20132015 as
E340 – 13.E340 – 15. DOI: 10.1520/E0340-15.10.1520/E0340-23.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E340 − 23
banding, coring, inclusions, and depth of carburization or decarburization. The information provided about variations in chemical
composition is strictly qualitative but the location of extremes in segregation will be shown. Chemical analyses or other means of
determining the chemical composition would have to be performed to determine the extent of variation. Macroetching will also
show the presence of discontinuities and voids, such as seams, laps, porosity, flakes, bursts, extrusion rupture, cracks, and so forth.
3.1.3 Other applications of macroetching in the fabrication of metals are the study of weld structure, definition of weld penetration,
dilution of filler metal by base metals, entrapment of flux, porosity, and cracks in weld and heat affected zones, and so forth. It
is also used in the heat-treating shop to determine location of hard or soft spots, tong marks, quenching cracks, case depth in
shallow-hardening steels, case depth in carburization of dies, carburization, effectiveness of stop-off coatings in carburization, and
so forth. In the machine shop, it can be used for the determination of grinding cracks in tools and dies.
3.1.4 Macroetching is used extensively for quality control in the steel industry, to determine the tone of a heat in billets with
respect to inclusions, segregation, and structure. Forge shops, in addition, use macroetching to reveal flow lines in setting up the
best forging practice, die design, and metal flow. For an example of the use of macroetching in the steel forging industry see
Method E381. Forging shops and foundries also use macroetching to determine the presence of internal faults and surface defects.
The copper industry uses macroetching for control of surface porosity in wire and bar. In the aluminum industry, macroetching is
used to evaluate extrusions as well as the other products such as forgings, sheets, and so forth. Defects such as coring, cracks, and
porthole die welds are identified.
4. Sampling
4.1 As in any method of examination, sampling is very important. When macroetching is used to solve a problem, the problem
itself largely dictates the source of the sample as to the location on the work piece and the stage of manufacture; for example, when
looking for pipe, the sample should represent the top of the ingot, or when looking for bursts or flakes, the sample should be taken
as soon after hot working as possible.
4.2 When macroetching is used as an inspection procedure, sampling ought to be done in an early stage of manufacturing so that,
if the material proves faulty, no wasteful unnecessary work is done. However, the sample should not be taken so early that further
working can introduce serious defects. In the steel industry, for example, the sample is usually taken after ingot breakdown and
after most chances of bursts or flakes occurring have passed. Billets or blooms going into small sizes are sampled after initial
breakdown. Material going into forging billets or die blocks is sampled near the desired finish size. Sampling may be done
systematically or on a random basis.
4.3 Samples may be cold cut from the source by any convenient fashion;method; saws and abrasive cutoff wheels are particularly
effective. The use of torch Torch cutting or hot cutting should be used only when necessary to cut a sample from a large piece.
The sample then is sectioned well away from the hot-cut surface. An example of permissible use of torch cutting is the excising
of a piece from a large plate and then cutting a sample for macroetching 44 in. to 5 in. (102(102 mm to 127 mm) away from the
torch-cut edge.
4.4 Some common methods of sampling, listed by source, are as follows:
4.5 Billets, Blooms, and Hot-Rolled Products—Disks are usually cut from these products near the end. Samples cut too close to
the end, however, may have false structures because of fish-tailing. Disks from large blooms are sometimes cut into smaller pieces
for ease in handling.
4.5.1 Forgings and Extrusions—Disks cut transverse to the long dimension will show flakes, bursts, and so forth. Forgings may
also be cut parallel to the long dimension to show flow lines. In complicated forgings, some thought will have to be given to the
proper method of cutting so as to show flow lines. Macroetching of an unprepared specimen will show surface defects such as
shuts, flats, seams, and so forth. In extrusions, coring and coarse grain are more commonly found in the back end of the extrusion.
4.5.2 Sheets and Plates—A sufficiently large sample should be taken when looking for surface defects. An ideal length would be
the circumference of the last roll, but this may be inconveniently long. Several samples totaling some given fraction of the
circumference can be used; however, there is always a chance then that a defect arising from faulty rolls would not be detected.
When seeking information on laminations, a transverse section is used. In many cases, however, to reduce the size of the specimen,
only a section out of the center of the plate may be taken.
4.5.3 Weldments—A disk cut perpendicular to the direction of welding will show weld penetration, heat affected zone, structure,
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TABLE 1 Macroetchants for Aluminum and Aluminum Alloys
Alloy Composition Procedure Comments
All NaOH 10 g Immerse sample 5 to 15 min in solution heated to 140 Good general-purpose etchant, can be
H O 100 mL to 160°F (60 to 70°C). Rinse in water, and remove used on almost all aluminum alloys.
smut in strong HNO solution. Rinse and repeat Does not require fine grinding.
etching if necessary.
All NaOH 10 g Immerse sample 5 min to 15 min in solution heated to Good general-purpose etchant, can be
H O 100 mL 140 °F to 160 °F (60°C to 70 °C). Rinse in water, and used on almost all aluminum alloys.
remove smut in strong HNO solution. Rinse and Does not require fine grinding.
repeat etching if necessary.
3XXX HCl (concentrated) 75 mL Mix fresh before using. Use at room temperature. May Used to develop grain structure. May be
4XXX HNO (concentrated) 25 mL be used as immersion etch or swabbed over diluted with 25 % water to slow down
5XXX HF (48 %) 5 mL specimen surface. Rinse specimen in warm water and etching. Does not require fine grinding.
6XXX dry.
High Si castings
High purity A1 HCl (concentrated) 45 mL Immerse specimen at room temperature until desired Tucker’s etch. General purpose etch for
1XXX HNO (concentrated) 15 mL contrast is developed. Rinse in warm water and dry. revealing microstructure of both cast and
3XXX HF (48 %) 15 mL wrought aluminum. Does not require fine
4XXX H O 25 mL grinding.
5XXX
6XXX
All except high Si HCl (concentrated) 15 mL Same as above. 1 + 2 Tucker’s. Same as above, but
castings HNO (concentrated) 5 mL slower acting.
HF (48 %) 5 mL
H O 75 mL
2XXX HCl (concentrated) 15 mL May be used as an immersion etch or swabbed over Flick’s reagent. Best results are obtained
High Cu alloys HF (48 %) 10 mL the specimen surface. When desired contrast is with a ground surface. 180 grit will
H O 90 mL obtained, rinse in water and remove deposits with suffice.
concentrated HNO . Rinse in warm water and dry.
and so forth. Careful preparation is usually rewarded with highly detailed structures giving a large amount of information. Welds
involving dissimilar metals will produce problems in etching. The best method is to etch the least corrosion-resistant portion first
and the more resistant portion afterwards. Occasionally, an intermediary etchant may be required. The boundaries between etched
and unetched portion will give an idea of weld penetration and dilution.
4.5.4 Castings—Cut the specimen to display the defect or feature being sought.
4.5.5 Machined and Ground Parts—When looking for grinding cracks, and so forth, the surface itself is used as a sample. Because
the machined or ground part is often the finished part, it may be undesirable to immerse the part in acid. In this case, other methods
such as dye penetrant methods may be more desirable.
5. Preparation
5.1 Sample preparation need not be elaborate. Any method of presenting a smooth surface with a minimum amount of cold work
will be satisfactory. Disks may be faced on a lathe or a shaper. The usual procedure is to take a roughing cut, then a finish cut.
This will generate a smooth surface and remove cold work from prior operations. Sharp tools are necessary to produce a good
specimen. Grinding is usually conducted in the same manner, using free-cutting wheels and light finishing cuts. When fine detail
is required, the specimen should be ground down through the series of metallographic papers (see Guide E3). Where necessary,
details are given in Tables 1-14the tabulation of procedures.
5.2 Care should be taken to examine the surface before and after etching to ensure induced damage from surface preparation does
not interfere with analysis. Specific guidance is included in the following sections.
5.3 After surface preparation, the sample is cleaned carefully with suitable solvents. Any grease, oil, or other residue will produce
uneven attack. an uneven etch response. Once cleaned, care should be taken not to touch the sample surface or contaminate it in
any way.
6. Solutions
6.1 The solutions used for macroetching are given in the tables listed under each alloy. In most cases a goodlaboratory grade of
E340 − 23
TABLE 2 Macroetchants for Beryllium and Beryllium Alloys
Metal Composition Procedure Comments
Be HCl 10 mL Either swab or immerse at room temperature for a few Works best on coarse grained Be.
NH Cl 4 g minutes, rinse in water and dry.
H O 90 mL
Be HCl 10 mL As above. An alternative when No. 1 does not work. Fine-grained
NH Cl 2 g metal may not give good results in either case.
Picric acid 2 g
H O 90 mL
TABLE 3 Macroetchants for Cobalt and Cobalt Alloys
Alloy Composition Procedure Comments
49Co-49Fe-V HCl 50 mL Immerse specimen in hot solution (140 to 180°F) for General structure,
Some Co-Cr alloys H O 50 mL 30 to 60 min. Rinse in hot water and dry. porosity.
25Cr-10Ni-8W HCl 50 mL Swab until desired contrast is obtained then rinse in Grain size, general
21Cr-20Ni- HNO 10 mL warm water and dry. structure.
3W-3Mo-1Cb FeCl 10 g
H O 100 mL
18Cr-10Ni-14W CuCl ·2NH Cl·2H O 2 g As above. As above.
2 4 2
FeCl 5 g
HNO 5 mL
HCl 50 mL
H O 80 m
TABLE 4 Macroetchants for Copper and Copper Alloys
Alloys Composition Procedure Comments
Cu and all brasses HNO 10 mL Immerse specimen in solution at room temperature Emphasize grains and cracks.
H O 90 mL for a few minutes. Rinse in water and dry.
Cu and all brasses HNO 50 mL As above. Brings out grain contrast, pits result
H O 50 mL unless agitated. Aluminum bronzes may
form smut which can be removed by brief
immersion in concentrated HNO .
Cu and all brasses HCl 30 mL As above. Good grain contrast.
FeCl 10 g
H O or ethanol 120 mL
Cu, high Cu alloys, K Cr O sat 2 g Immerse specimen in solution at room temperature Emphasizes grain boundaries and oxide
2 2 7
phosphorus, tin soln of NaCl for 15 to 30 min then swab with fresh solution. inclusions.
bronzes H SO Rinse in warm water and dry.
2 3
H O
All HNO 50 mL Immerse specimen in solution at room temperature. Brilliant deep etch.
AgNO 5 g Rinse in warm water and dry.
H O 50 mL
Brass 20 % acetic acid 20 mL As above. Strain lines.
5 % chromic acid 10 mL
10 % FeCl in H O 5 mL
3 2
Brass 20 % CH COOH 20 mL As above. Strain lines.
5 % H CrO 10 mL
2 4
10 % FeCl in H O 5 mL
3 2
Silicon brass or bronze CrO 40 g Immerse specimen in solution at room temperature,
NH Cl 7.5 g rinse in warm water and dry.
HNO (concentrated) 50 mL
H SO (concentrated) 8 mL
2 4
H O 100 mL
reagent should be used but need not be chemically pure or of analytical quality. The so-called technical grades are usually
satisfactory. used. Technical grades may provide satisfactory results. The solution should be clean and clear, free of suspended
particles, scum, and so forth. Solutions may lose effectiveness through age or reuse, and should be replaced if not performing
consistently.
6.2 Caution must be observed in mixing. Many of the etchants are strong acids. In all cases, the various chemicals should be added
E340 − 23
TABLE 5 Macroetchants for Iron and Steel
Alloys Composition Procedure Comments
Plain and alloy steels, HCl (concentrated) 50 mL Immerse specimen in solution heated to 160 to General purpose.
high-speed and tool steels, H O 50 mL 180°F for 15 to 30 min. Desmut by vigorous
cutlery (12–14 % Cr) and scrubbing with vegetable fiber brush under
stainless steels running water. Stainless steels may be desmutted
by dipping in a warm 20 % HNO to give a bright
finish.
Plain and alloy steels, HCl (concentrated) 50 mL Immerse specimen in solution heated to 160 °F to General purpose.
high-speed and tool steels, H O 50 mL 180 °F for 15 min to 30 min. Desmut by vigorous
cutlery (12 %–14 % Cr) and scrubbing with vegetable fiber brush under
stainless steels running water. Stainless steels may be desmutted
by dipping in a warm 20 % HNO to give a bright
finish.
High-alloy steels HCl (concentrated) 50 mL Immerse specimen for 10 to 15 min in solution at Ratio HCl:HNO runs 2:1 to 3:1.
HNO (concentrated) 25 mL room temperature. Rinse in warm water and dry.
H O 25 mL
High-alloy steels HCl (concentrated) 50 mL Immerse specimen for 10 min to 15 min in Ratio HCl:HNO runs 2:1 to 3:1.
HNO (concentrated) 25 mL solution at room temperature. Rinse in warm
H O 25 mL water and dry.
Plain and alloy steels, cutlery HCl (concentrated) 38 mL Immerse specimen for 15 to 45 min in solution Works well on 12 % Cr steel.
steels H SO (concentrated) 12 mL heated to 160 to 180°F. Rinse in warm water and
2 4
H O 50 mL dry.
Plain and alloy steels, cutlery HCl (concentrated) 38 mL Immerse specimen for 15 min to 45 min in Works well on 12 % Cr steel.
steels H SO (concentrated) 12 mL solution heated to 160 °F to 180 °F. Rinse in
2 4
H O 50 mL warm water and dry.
High-alloy steels HNO (concentrated) 10 mL Immerse specimen in solution heated to 160 to Ratio HNO -HF varies.
3 3
HF (48 %) 4 mL 180°F until desired etch is obtained and rinse in
H O 87 mL warm water and dry.
H O 87 mL
High-alloy steels HNO (concentrated) 10 mL Immerse specimen in solution heated to 160 °F to Ratio HNO -HF varies.
3 3
HF (48 %) 4 mL 180 °F until desired etch is obtained and rinse in
H O 87 mL warm water and dry.
to
HNO (concentrated) 40 mL
HF (48 %) 10 mL
H O 50 mL
Stainless steels, high-alloy HCl (concentrated) 50 mL Mix HCl and water then heat to 160 to 170°F. Produces bright finish.
steels H O 50 mL Immerse specimen and add H O in several
2 2 2
H O (30 %) 20 mL parts. Do not mix. Make each subsequent
2 2
addition after foaming from previous addition has
stopped.
Stainless steels, high-alloy HCl (concentrated) 50 mL Mix HCl and water then heat to 160 °F to 170 °F. Produces bright finish.
steels H O 50 mL Immerse specimen and add H O in several
2 2 2
H O (30 %) 20 mL parts. Do not mix. Make each subsequent
2 2
addition after foaming from previous addition has
stopped.
Austenitic stainless steels HCl (concentrated) 50 mL Immerse specimen in solution which may be Marble’s reagent. Light etch, good for
sat heated or not depending upon alloy. Time also structure.
soln 25 mL depends on alloy. Rinse in warm water and dry.
CuSO in H O
4 2
Austenitic stainless steels HCl (concentrated) 50 mL Immerse specimen in solution which may be Marble’s reagent. Light etch, good for
saturated solution heated or not depending upon alloy. Time also structure.
of 25 mL depends on alloy. Rinse in warm water and dry.
CuSO in H O
4 2
Plain and low-alloy steels (NH ) S O (ammo- 10 g Swab solution at room temperature over Grain size, weldments.
4 2 2 8
nium persulfate) specimen. Rinse and dry.
H O 100 mL
Plain and alloy steels CuCl 2.5 g Immerse in solution at room temperature until a Stead’s reagent. Salts dissolved in HCl
MgCl 10 g coppery sheen appears. Rinse thoroughly and with minimum of hot water. To bring out
HCl (concentrated) 5 mL dry. P-rich areas and P banding.
Alcohol—up to 250 mL
Mild steel, Bessemer and high CuCl 90 g The surface should be rubbed with cloth soaked Fry’s reagent. Before etching, sample
N steel HCl (concentrated) 120 mL in etching solution. Wash in alcohol or rinse in should be heated to 200 to 250°C (302
H O 100 mL HCl (1 + 1) after etching to prevent deposition of to 482°F) for 5 to 30 min depending on
copper. condition of steel. To show strain lines
due to cold work.
E340 − 23
Alloys Composition Procedure Comments
Mild steel, Bessemer and high CuCl 90 g The surface should be rubbed with cloth soaked Fry’s reagent. Before etching, sample
N steel HCl (concentrated) 120 mL in etching solution. Wash in alcohol or rinse in should be heated to 200 °C to 250 °C
H O 100 mL HCl (1 + 1) after etching to prevent deposition of (302 °F to 482 °F) for 5 min to 30 min
copper. depending on condition of steel. To
show strain lines due to cold work.
Plain and alloy steels CuCl 45 g As above. Modified Fry’s reagent. Same as for
HCl (concentrated) 180 mL reagent No. 9 but modified by Wazau,
H O 100 mL may give more contrast specimen can
be washed in water without depositing
copper.
Plain and alloy steels CuCl 45 g As above. Modified Fry’s reagent. Same as Fry’s
HCl (concentrated) 180 mL Reagent but modified by Wazau, may
H O 100 mL give more contrast. Specimen can be
washed in water without depositing
copper.
Stainless and high-Cr steels HCl 10 mL Immerse specimen in solution at room Vilella’s reagent.
Alcohol 100 mL temperature until desired contrast is obtained.
Picric acid 1 g Rinse and dry.
Plain and alloy steels HCl (concentrated) 6 to 12 mL Electrolytic, 5 to 10 A per square inch, specimen Small specimens, <20 in. area.
H O 100 mL vertical, rinse, brush, and dry.
Plain and alloy steels HCl (concentrated) 6 mL Electrolytic, specimen moves past a cathode bar, For specimens over 20 in. area,
H O 100 mL 30 to 40 A per inch of specimen width, rinse, blooms, billets, and slabs.
HBO 1 g brush, and dry.
Plain and alloy steels H O 50 mL Immerse in solution at room temperature until “3-2-1 etch.” Specimens can be
HCl (concentrated) 33 mL reaction stops. Rinse in warm water, brush, dry completely immersed. Refresh for
H O (30 %) 17 mL immediately. reuse with small additions of 30 %
2 2
H O
2 2
E340 − 23
TABLE 6 Macroetchants for Stainless Steels and High-Temperature Alloys
Alloys Composition Procedure Comments
Stainless steels and iron- HCl (concentrated) 50 mL Immerse specimen in solution heated to General purpose.
base H O 50 mL 160 to 180°F for 30 min. Desmut by
high-temperature alloys vigorous scrubbing with vegetable brush
under running water. Stainless steels may
be desmutted by dipping in warm 20 %
HNO to give bright finish. Dropwise or
slow addition of H O is often effective in
accelerating etching.
Stainless steels and iron- HCl (concentrated) 50 mL Immerse specimen in solution heated to General purpose.
base H O 50 mL 160 °F to 180 °F for 30 min. Desmut by
high-temperature alloys vigorous scrubbing with vegetable brush
under running water. Stainless steels may
be desmutted by dipping in warm 20 %
HNO to give bright finish. Dropwise or
slow addition of H O is often effective in
accelerating etching.
Iron-, cobalt-, and nickel- HCl (concentrated) 50 mL Immerse specimen in solution at room Ratio HCl + HNO runs 2 + 1 to
base HNO (concentrated) 25 mL temperature for 10 to 30 min. Rinse and 3 + 1
high-temperature alloys H O 25 mL dry.
Iron-, cobalt-, and nickel- HCl (concentrated) 50 mL Immerse specimen in solution at room Ratio HCl + HNO runs 2 + 1 to
base HNO (concentrated) 25 mL temperature for 10 min to 30 min. Rinse 3 + 1
high-temperature alloys H O 25 mL and dry.
Stainless steels and high- HNO 10 mL Immerse specimen in solution heated to Ratio HNO -HF varies.
3 3
temperature alloys HF (48 %) 3 mL 160 to 180°F until desired contrast is
H O 87 mL obtained. Rinse and dry.
Stainless steels and high- HNO 10 mL Immerse specimen in solution heated to Ratio HNO -HF varies.
3 3
temperature alloys HF (48 %) 3 mL 160 °F to 180°F until desired contrast is
H O 87 mL obtained. Rinse and dry.
to
HNO (concentrated) 40 mL
HF (48 %) 10 mL
H O 50 mL
Austenitic stainless steels I (NH ) SO 15 g Combine I and II then add III. Immerse Lepito’s etch. I, mix fresh, grain
4 2 4
and H O 75 mL specimen in solution at room temperature structure.
nickel base alloys II FeCl 250 g until desired contrast is obtained.
HCl 100 mL
(concentrated) 30 mL
III HNO
(concentrated)
Austenitic stainless steels HCl (concentrated) 50 mL Mix HCl and water then heat, immerse
and H O 50 mL specimen and add H O in several parts.
2 2 2
high-temperature alloys H O (30 %) 20 mL Do not mix. Make each subsequent
2 2
addition after foaming from previous
addition has stopped.
Austenitic stainless steels HCl (concentrated) 50 mL Immerse specimens in solution which may Marble’s reagent. Light etch, good
and Sat soln of 25 mL be heated up to 170°F until desired for structures. Amount of CuSO
high-temperature alloys CuSO in H O contrast is obtained. Rinse and dry. solution may be increased to 1 + 1
4 2
ratio for difficult alloys.
Austenitic stainless steels HCl (concentrated) 50 mL Immerse specimens in solution which may Marble’s reagent. Light etch, good
and Sat soln of 25 mL be heated up to 170 °F until desired for structures. Amount of CuSO
high-temperature alloys CuSO in H O contrast is obtained. Rinse and dry. solution may be increased to 1 + 1
4 2
ratio for difficult alloys.
slowly to the water or solvent while stirring. In the cases where hydrofluoric acid is used, the solution should be mixed and used
in polyethylene vessels. (Warning—Hydrofluoric acid must not be allowed to contact the skin since it can cause painful serious
ulcers if not washed off immediately.skin.)
7. Procedure
7.1 Many of the solutions are aggressive and may give off irritating and corrosive fumes. Etching should be done in a
well-ventilated room, preferably under a fume hood. The solution should be mixed and placed in a corrosion resistant tray or dish
and brought to the operating temperature. The specimen or specimens should be placed in a tray of stainless steel screen or on some
non-reactive support. Glass rods often are placed on the bottom of the acid container and the specimens laid directly on the rods.
E340 − 23
TABLE 7 Macroetchants for Lead and Lead Alloys
Alloy Composition Procedure Comments
Lead and lead A. H O 250 mL Add A to B and let precipitate redissolve. If B is added to A an
alloys NH OH (sp gr 0.90) 140 mL insoluble precipitate forms.
HNO (concentrated) 60 mL Add C to mixture of A and B after precipitate has redissolved.
Molybdic acid (85 %) 100 mL
B. H O 960 mL Swab surface of the specimen with mixed solution until desired
HNO (concentrated) 400 mL contrast is obtained. Rinse and dry.
C. Glacial acetic acid 100 mL
Antimonial lead A. Glacial acetic acid 30 mL Prepare surface on silk velvet wheel with Al O abrasive at 150
2 3
HNO (concentrated) 40 mL rpm. Etch with solution A at 42°C then repolish until bright. Reetch
H O 16 mL with B at room temperature for 1 to 2 h.
B. Glacial acetic acid 1 mL
H O 400 mL
Antimonial lead A. Glacial acetic acid 30 mL Prepare surface on silk velvet wheel with Al O abrasive at 150
2 3
HNO (concentrated) 40 mL rpm. Etch with solution A at 42 °C then repolish until bright.
H O 16 mL Reetch with B at room temperature for 1 to 2 h.
B. Glacial ac
...