ASTM E407-99

Standard Practice for Microetching Metals and Alloys

SCOPE
1.1 This practice covers chemical solutions and procedures to be used in etching metals and alloys for microscopic examination. Safety precautions and miscellaneous information are also included.
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific cautionary statements, see 6.1 and Table 2.

General Information

• Status: Historical
• Publication Date: 09-Oct-1999
• ICS: 49.025.20 - Aluminium
• Technical Committee: E04 - Metallography
• Drafting Committee: E04.01 - Specimen Preparation

Relations

• Replaced By: ASTM E407-07 - Standard Practice for Microetching Metals and Alloys
• Effective Date: 01-May-2007
• Referred By: ASTM F1314-18 - Standard Specification for Wrought Nitrogen Strengthened 22 Chromium–13 Nickel–5 Manganese–2.5 Molybdenum Stainless Steel Alloy Bar and Wire for Surgical Implants (UNS S20910)
• Effective Date: 10-Oct-1999
• Referred By: ASTM E930-18 - Standard Test Methods for Estimating the Largest Grain Observed in a Metallographic Section (ALA Grain Size)
• Effective Date: 10-Oct-1999
• Referred By: ASTM E1077-14(2021) - Standard Test Methods for Estimating the Depth of Decarburization of Steel Specimens
• Effective Date: 10-Oct-1999
• Referred By: ASTM E1351-01(2020) - Standard Practice for Production and Evaluation of Field Metallographic Replicas
• Effective Date: 10-Oct-1999
• Referred By: ASTM E1180-08(2021) - Standard Practice for Preparing Sulfur Prints for Macrostructural Evaluation
• Effective Date: 10-Oct-1999
• Referred By: ASTM F1108-21 - Standard Specification for Titanium-6Aluminum-4Vanadium Alloy Castings for Surgical Implants (UNS R56406)
• Effective Date: 10-Oct-1999
• Referred By: ASTM F75-23 - Standard Specification for Cobalt-28 Chromium-6 Molybdenum Alloy Castings and Casting Alloy for Surgical Implants (UNS R30075)
• Effective Date: 10-Oct-1999
• Referred By: ASTM F3001-14(2021) - Standard Specification for Additive Manufacturing Titanium-6 Aluminum-4 Vanadium ELI (Extra Low Interstitial) with Powder Bed Fusion
• Effective Date: 10-Oct-1999
• Referred By: ASTM E1382-97(2023) - Standard Test Methods for Determining Average Grain Size Using Semiautomatic and Automatic Image Analysis
• Effective Date: 10-Oct-1999
• Referred By: ASTM E112-13(2021) - Standard Test Methods for Determining Average Grain Size
• Effective Date: 10-Oct-1999
• Referred By: ASTM E2014-17 - Standard Guide on Metallographic Laboratory Safety
• Effective Date: 10-Oct-1999
• Referred By: ASTM F2229-21 - Standard Specification for Wrought, Nitrogen Strengthened 23Manganese-21Chromium-1Molybdenum Low-Nickel Stainless Steel Alloy Bar and Wire for Surgical Implants (UNS S29108)
• Effective Date: 10-Oct-1999
• Referred By: ASTM F3056-14(2021) - Standard Specification for Additive Manufacturing Nickel Alloy (UNS N06625) with Powder Bed Fusion
• Effective Date: 10-Oct-1999
• Referred By: ASTM F2886-17(2023) - Standard Specification for Metal Injection Molded Cobalt-28Chromium-6Molybdenum Components for Surgical Implant Applications
• Effective Date: 10-Oct-1999

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E407–99
Standard Practice for
Microetching Metals and Alloys
This standard is issued under the fixed designation E407; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 4. Summary of Practice
1.1 This practice covers chemical solutions and procedures 4.1 Table1isanalphabeticallistingofthemetals(including
to be used in etching metals and alloys for microscopic rare earths) and their alloys for which etching information is
examination. Safety precautions and miscellaneous informa- available. For each metal and alloy, one or more etchant
tion are also included. numbers and their corresponding use is indicated. Alloys are
1.2 This standard does not purport to address all of the listed as a group or series when one or more etchants are
safety concerns, if any, associated with its use. It is the common to the group or series. Specific alloys are listed only
responsibility of the user of this standard to establish appro- when necessary. When more than one etchant number is given
priate safety and health practices and determine the applica- for a particular use, they are usually given in order of
bility of regulatory limitations prior to use. For specific preference. The numbers of electrolytic etchants are italicized
cautionary statements, see 6.1 and Table 2. to differentiate them from nonelectrolytic etchants.
4.2 Table 2 is a numerical listing of all the etchants
2. Referenced Documents
referencedinTable1andincludesthecompositionandgeneral
2.1 ASTM Standards: procedure to be followed for each etchant.
D1193 Specification for Reagent Water
4.3 To use the tables, look up the metal or alloy of interest
E7 Terminology Relating to Metallography in Table 1 and note the etchant numbers corresponding to the
results desired. The etchant composition and procedure is then
3. Terminology
located in Table 2 corresponding to the etchant number.
3.1 Definitions:
4.4 If the common name of an etchant is known (Marble’s,
3.1.1 For definition of terms used in this standard, see
Vilella’s,etc.),anditisdesiredtoknowthecomposition,Table
TerminologyE7.
3 contains an alphabetical listing of etchant names, each coded
3.2 Definitions of Terms Specific to This Standard:
with a number corresponding to the etchant composition given
3.2.1 tint etch—an immersion etchant that produces color
in Table 2.
contrast, often selective to a particular constituent in the
5. Significance and Use
microstructure, due to a thin oxide, sulfide, molybdate, chro-
mate or elemental selenium film on the polished surface that 5.1 This practice lists recommended methods and solutions
reveals the structure due to variations in light interference
for the etching of specimens for metallographic examination.
effects as a function of the film thickness (also called a 88stain Solutions are listed to highlight phases present in most major
etch”).
alloy systems.
3.2.2 vapor-deposition interference layer method— a tech-
6. Safety Precautions
niqueforproducingenhancedcontrastbetweenmicrostructural
constituents, usually in color, by thin films formed by vacuum 6.1 Beforeusingormixinganychemicals,allproductlabels
deposition of a dielectric compound (such as ZnTe, ZnSe, and pertinent Material Safety Data Sheets (MSDS) should be
TiO ,ZnSorZnO)withaknownindexofrefraction,generally read and understood concerning all of the hazards and safety
duetolightinterferenceeffects(alsoknownasthe“Pepperhoff precautions to be observed. Users should be aware of the type
method”). of hazards involved in the use of all chemicals used, including
those hazards that are immediate, long-term, visible, invisible,
and with or without odors.
This practice is under the jurisdiction of ASTM Committee E-4 on Metallog-
6.1.1 ConsulttheproductlabelsandMSDSsforrecommen-
raphy and is the direct responsibility of Subcommittee E04.01 on Sampling,
dations concerning proper protective clothing.
Specimen Preparation, and Photography.
Current edition approved October 10, 1999. Published November 1999.
Annual Book of ASTM Standards, Vol 11.01.
Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E407–99
TABLE 1 Etchants for Metals
NOTE 1—Electrolytic etchants are italicized.
Metal Etchants Uses
Aluminum Base:
Pure Al 1a, 2, 3 general structure
4, 5 grain structure under polarized light
1b grain boundaries and slip lines
1000 series 1a, 3, 2 general structure
4, 5 grain structure under polarized light
6, 7 phase identifications
2000 series 3, 2, 1a general structure
8a, 6, 7 phase identifications
3000 series 3, 1a general structure
4, 5 grain structure under polarized light
8a, 6, 7 phase identifications
4000 series 3, 1a general structure
5000 series 3, 1a, 2, 6, 8a general structure
4, 5 grain structure under polarized light
6000 series 3, 1a, 2, 6, 8a, 222 general structure
4, 5 grain structure under polarized light
1a, 2, 7, 6, 8a phase identifications
7000 series 3, 1a, 2 general structure
4, 5 grain structure under polarized light
3b, 6 phase identifications
Beryllium Base:
Pure Be 9, 10 general structure via polarized light
Be alloys 11 general structure
Chromium Base: 12, 13c general structure
Cobalt Base:
Pure Co 14, 15, 16, 17 general structure
Hard-facing and tool metals 18, 19, 20 general structure
High-temperature alloys 20, 18, 16, 21, 22b, 24, 25 general structure
19 phase identification
Columbium Base (see niobium base)
Copper Base:
Pure Cu 26, 27, 28, 29, 30, 31d, 32, 33, 34b, 35, general structure
36, 37, 38, 39, 40, 41, 42, 8b, 210, 215
43, 28 chemical polish and etch
Cu-Al (aluminum bronze) 44, 31d, 34b, 35, 36, 37, 38, 39, 40, general structure
45, 215
Cu-Be 46, 41, 45 general structure
Cu-Cr 41 general structure
Cu-Mn 41 general structure
Cu-Ni 34, 47, 48, 40, 49, 50 general structure
Cu-Si 41 general structure
Cu-Sn (tin bronze) 51, 52 general structure
Admiralty metal 8b general structure
Gilding metal
Cartridge brass
Free-cutting brass
Nickel silver 31d, 32, 33, 41, 42, 49 general structure
Cu alloys 26, 27, 28, 29, 30, 44, 41, 31d, 32, 33, general structure
34b, 35, 36, 37, 38, 39, 210, 215
53, 43, 28, 49 chemical polish and etch
42, 49, 210 darkens beta in alpha-beta brass
54 etching of cold worked brass
Dysprosium Base: 55, 56 general structure
Erbium Base: 55, 56 general structure
E407–99
TABLE 1 Continued
Metal Etchants Uses
Gadolinium Base: 55, 56, 57 general structure
Germanium Base: 58, 59, 60 general structure
Gold Base:
Pure Au 61, 62 general structure
63 chemical polish and etch
Au alloys 64b, 62 general structure
63 chemical polish and etch
>90 % noble metals 61 general structure
<90 % noble metals 65 general structure
Hafnium base: 66, 67, 68, 69, 70 general structure
71 grain structure under polarized light
72 chemical polish and etch
Holmium Base: 55, 56 general structure
Iridium Base: 73c general structure
Iron Base:
Pure Fe 74a grain boundaries
75 substructure
210 colors ferrite grains
Fe + C 76, 74a, 77, 78, 79 general structure
and 74a, 77, 31a, 223 ferrite grain boundaries
Fe + <1C + <4 % additions 80, 81, 82 prior austenitic grain boundaries in martensitic and
bainitic steels
78, 222a untempered martensite
31b, 78 carbides and phosphides (matrix darkened, carbides
and phosphides remain bright)
83 cementite attacked rapidly, sustenite less, ferrite and
iron phosphide least
84 overheating and burning
85 stains carbides
86 chemical polish-etch
210, 211 colors ferrite
213, 214 colors carbides
216 colors lath martensite in low-carbon high-alloy grades
222b for dual phase steels; reveals pearlite, darkens
martensite and outlines austenite
Fe + 4–12 Cr 80, 87, 88, 89, 90, 91, 79, 210 general structure
86 chemical polish-etch
Fe + 12–30 Cr + <6 Ni (400 Series) 80, 87, 88, 89, 34, 40, 92, 93, 94, 95, 91, 226 general structure
96, 97, 98 signs phase
31c carbides
86 chemical polish-etch
219 grain boundary etch
220 darkens delta ferrite
Fe + 12–20 Cr + 4–10 Ni + <7 % 80, 31c, 89, 99, 100, 91 general structure
other elements (controlled trans- 31c carbides
formation, precipitation harden- 86 chemical polish-etch
ing, stainless maraging alloys) 220 darkens delta ferrite
Fe + 15–30 Cr + 6–40 Ni + <5 % 13b, 89, 87, 88, 83a, 80, 94, 95, 91, general structure
other elements (300 Series) 101, 212, 221, 226
13a, 102, 31c, 48c, 213 carbides and sensitization
and 48, 96, 97, 98 stains sigma phase
Fe + 16–25 Cr + 3–6 Ni + 5–10 103, 104, 98 delineates sigma phase and
Mn (200 series) 103, 104 welds of dissimilar metals
86 chemical polish-etch
219 grain boundary etch (no twins)
220 darkens delta ferrite
High temperature 89, 25, 105, 106, 97, 212, 221 general structure
107, 108, 213 g8 precipitate
86 chemical polish-etch
Nonstainless maraging steels 109, 89, 99, 100, 221 general structure
83b grain boundaries
86 chemical polish-etch
E407–99
TABLE 1 Continued
Metal Etchants Uses
Tool steels 74a, 80, 14 general structure
110 grain boundaries in tempered tool steel
210, 211 colors ferrite, lower alloy grades
214, 214 colors cementite
224, 225 carbides attacked and colored
Superalloys 86, 87, 94, 221, 226 general etch
111 general structure
111 g8 depletion
Lead Base:
Pure Pb 57, 112 general structure
113 for alternate polishing and etching
Pb + <2 Sb 114, 115, 57, 74b general structure
113 for alternate polishing and etching
Pb + >2 Sb 114, 57, 74b general structure
113 for alternate polishing and etching
Pb + Ca 112 general structure
113 for alternate polishing and etching
Pb alloys 116, 117b general structure
Babbitt 74b general structure
Magnesium Base:
Pure Mg 118, 119, 74a, 120, 121, 122 general structure
123 stain-free polish-etch
Mg-Mn 119, 74a, 124, 122 general structure
Mg-Al, Mg-Al-Zn (Al + Zn <5 %) 118, 119, 74a, 125, 124, 123, 122 general structure
120, 125, 126, 127 phase identification
124, 126, 127 grain structure
Mg-Al, Mg-Al-Zn (Al + Zn >5 %) 118, 119, 74a, 125, 124, 121, 122 general structure
120, 125, 126, 127 phase identification
Mg-Zn-Zr 118, 119, 74a, 1d, 128, 124, 126, general structure
and 127, 121, 122
Mg-Zn-Th-Zr 120, 121 phase identification
Mg-Th-Zr 118, 119, 74a, 1d, 124, 127, 121, 122 general structure
and
Mg-Rare Earth-Zr 120, 121 phase identification
Molybdenum Base: 98c, 129, 130, 131 general structure
As cast 132a chemical polish prior to etching
Nickel Base:
Pure Ni and high Ni alloys 133, 134, 47, 135, 136, 25, 108, 31c general structure
137 grain boundary sulfidation
Ni-Ag 38, 138, 50, 139 general structure
Ni-Al 50, 140, 141, 142, 89, 143 general structure
Ni-Cr 144, 50, 83, 134, 145, 98, 146, 147, 13a general structure
Ni-Cu 38, 138, 50, 133, 140, 25, 134, 47, general structure
48b, 94, 108,34
Ni-Fe 50, 140, 141, 83, 134, 148, 40, 107, 149 general structure
74e, 25, 150 orientation pitting
Ni-Mn 74e general structure
Ni-Mo 143 general structure
Ni-Ti 143, 151, 50, 133 general structure
Ni-Zn 152 general structure
Superalloys 94, 105, 138, 153, 12, 87, 89, 212, 226 general structure
25, 94 grain size
107, 111, 13a reveals microstructural inhomogeneity
133 grain boundary sulfidation
154 fine precipitation structure
19b, 155, 156 differential matrix and nonmetallic staining
22a for passive alloys (for example, UNS Alloy N06625)
157 specific for UNS Alloy N10004
107 submicroscopic structure in aged super-alloys particu-
larly for electron microscopy. Stains the matrix when
g8 precipitates are present
154 g8 banding
18 pre-etch activation for passive specimens
213 colors carbide and g8
E407–99
TABLE 1 Continued
Metal Etchants Uses
Niobium (Columbium) Base: 129, 66, 158, 159, 160, 161, 162, 163 general structure
164, 129, 160 grain boundaries
Osmium Base: 165a general structure
165a etch-polishing for viewing grains with polarized light
Palladium Base:
Pure Pd 61, 166, 62, 165a general structure
Pd alloys 166, 64a, 62, 165a general structure
>90 % noble metals 61 general structure
<90 % noble metals 65 general structure
Platinum Base:
Pure Pt 64a, 73a general structure
167 electrolytic polish and etch
Pt Alloys 64b, 73a general structure
167 electrolytic polish and etch
>90 % noble metals 61 general structure
<90 % noble metals 65 general structure
Pt-10 % Rh 168 general structure
Plutonium Base: 169 general structure
Rhenium Base: 13b,98c, 132b, 170a general structure
Rhodium Base: 171 general structure
Ruthenium Base: 73b general structure
73b etch-polishing for viewing grains with polarized light
Silver Base:
Pure Ag 172, 173, 62 general structure
Ag alloys 65, 61, 174, 175, 62 general structure
Ag-Cu alloys 130 general structure
Ag-Pd alloys 173 general structure
Ag solders 173, 176 general structure
Tantalum Base:
Pure Ta 177 general structure
Ta alloys 159, 66, 178, 163, 161, 179 general structure
164 grain boundaries and inclusions
158 grain boundaries—retains carbide precipitate
Thorium Base:
Pure Th 185 general structure
Th alloys 185 general structure
Tin Base:
Pure Sn 74d, 180, 151 general structure
181 grain boundaries
Sn-Cd 74d general structure
Sn-Fe 74d, 177a general structure
Sn-Pb 182, 183, 74b general structure
116 darkens Pb in Sn-Pb eutectic
Sn coatings (on steel) 183 general structure
Babbitts 184 general structure
Sn-Sb-Cu 74b general structure
Titanium Base:
Pure Ti 186, 187, 67, 68, 69, 217 general structure
188 removes stain
72 chemical polish and etch
Ti-5 Al-2,5 Sn 189 reveals hydrides
Ti-6 Al-6 V-2 Sn 190 Stains alpha and transformed beta, retained beta re
mains white
Ti-Al-Zr 191 general structure
Ti-8Mn 192 general structure
Ti-13 V-11 Cr-3 Al (aged) 192 general structure
Ti-Si 193 general structure
Ti alloys 186, 187, 192, 194, 158, 132b, 1c, 67, general structure
68, 69, 3a, 218
11, 1c reveals alpha case
72, 192, 178 chemical polish and etch
170a outlines and darkens hydrides in some alloys
188 removes stain
E407–99
TABLE 1 Continued
Metal Etchants Uses
Tungsten Base:
Pure W 98c, 131 general structure
As cast 132a chemical polish prior to etching
W-Th 209 general structure
Uranium Base:
Pure U 67, 69, 195, 196 general structure
U + Zr 68 general structure
U beryllides 170a general structure
U alloys 67, 69, 195, 96 general structure
207 carbides
Vanadium Base:
Pure V 170b, 165b general structure
197, 198 grain boundaries
V alloys 199, 198 general s
...