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Metallographic Etching


* Note a single $35 hazmat US DOT paperwork fee is applied to each etchant order*
**Shipment is by Fed Ex hazmat ground, approximate cost $50 per etchant**
***The recommended Shelf Life for PACE Etchants is 3 months, although if stored properly this time can increase. Note in many cases as the effectiveness of the etchant decreases, they may still work with extended etching times***
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Metallographic Etchants (Technical)

COMMON ETCHANTS

CAUTION:Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacuters SDS (Safety Data Sheets). Also review the COMMENTS and CONDITIONS Section for each etchant.

Recommended Etchants

Aluminum alloys High carbon steel
Metallographic micrograph of aluminum Metallographic micrograph of high carbon steel
Brasses and Bronzes Stainless steel
Metallographic micrograph of Bronze Metallographic micrograph of stainless steel
Cast Iron Tin alloys
Metallographic micrograph of cast iron Metallographic micrograph of tin
Copper alloys Zinc alloys
Metallographic micrograph of copper Metallographic micrograph of zinc
Welding or Low carbon steels Ceramics
Metallographic micrograph of low carbon steel Metallographic micrograph of BeO
Hastelloy and Nickel Superalloys    
Metallographic micrograph of low carbon steel    

The following table lists the most commonly used etchants

Etchant Composition Conc. Conditions Comments
Adler Etchant Copper ammonium chloride
Hydrochloric acid
Ferric chloride, hydrated
DI Water
9 grams
150 ml
45 grams
75 ml
Immersion is recommended for several seconds For etching 300 series stainless steel and other superalloys
Al-NaOH Etchant NaOH
Distilled water
25 grams
250 ml
Immersion is recommended for several seconds For etching aluminum alloys
Ammonium Persulfate Etchant (NH4)2S2O8
Distilled water
50 grams
245 ml
Immersion is recommended for several seconds For brasses, especially brasses containing Cobalt
ASTM No. 30 Ammonia
Hydrogen Peroxide (3%)
DI Water
62.5 ml
125 ml

62.5 ml
Mix Ammonia and water before adding peroxide. Must be used fresh. Swab 5-45 seconds For etching copper, copper alloys and copper-silver alloys
ASTM 97

KOH
Distilled water

187.5 gram
245 ml
Electrolytic at 2.5 V for few seconds Fe-Cr-Ni alloys - Stains siga and chi yellow to red brown, ferrite gray to blue gray, carbides barely touched, austenite not touched
ASTM. No. 157 CrO3
HCl
Distilled water
31.25 grams
187.54 ml
62.5 ml
Immersion is recommended for several seconds Hastelloy
Beraha's Distilled water
Na2S2O3
7.5 grams K2S2O5
250 ml
25 grams
7.5 grams
Immersion is recommended for several seconds For etching tool steel - Colors ferrite, martensite, bainite, and pearlite. Cementite unaffected
Carpenters Stainless Steel Etch FeCl3
CuCl2
Hydrochloric acid
Nitric acid
Ethanol
8.5 grams
2.4 grams
122 ml
6 ml
122 ml
Immersion etching at 20 degrees Celsius For etching duplex and 300 series stainless steels
Copper No.1 Nitric acid
Distilled water
125 ml
125 ml
Immersion etching at 20 degrees Celsius Copper and brass Etchant
Copper No.2 Distilled water
HCl
FeCl3
200 ml
50 ml
10 grams
Immersion etching at 20 degrees Celsius Copper and brass Etchant
CU-PASS-SOL CuSO4-5H2O
H2SO4
Distilled water
40 grams
1.5 ml
245 ml
  This test is recommended for the detection of free iron on the surface of austenitic stainless steels in the 200 and 300 series, precipitation hardened stainless steels, and ferritic 400 series stainless steels having a minimum of 16 % chromium. A copper color on the metal surface (brown or pinkish) indicates that surface iron is still present and thus the part failures the test. If no reaction occurs it is considered a test pass
Dichromate H2SO4
Distilled water
Ssaturated NaCl
K2Cr2O7
36 ml
445 ml
18 ml
8.9 grams
  Cu-Sn (tin bronze)
Fry's Etchant HCl
CuCl2, 75 ml d
Distilled water
Denatured alcohol
100 ml
12.5 grams
75 ml
65 ml
  Fry's reagent for martensitic and precipitation hardenable grades of stainless steel
Inconel Etchant

Solution A:
HNO3
Distilled water
Solution B:
HCl
Distilled water
Solution C:
H2O2, 50 ml
Distilled water


50 ml
40 ml

75 ml
15 ml

35 ml
50 ml
Do not STORE MIXED SOLUTIONS IN CLOSED CONTAINERS.Use Fresh and discard after mixing. Macro etchant for Inconel-type alloys on NiCr and Ni-Fe-Cr basis. Etchant for Ni-Nb, Ni-Ta, Ni-Si, Ni-Co-Cr alloys
Kalling's No. 2 CuCl2
Hydrochloric acid
Ethanol
5 grams
100 ml
100 ml
Immersion or swabbing etch at 20 degrees Celsius For etching duplex and 400 series stainless steels and Ni-Cu alloys and superalloys.
Kellers Etch Distilled water
Nitric acid
Hydrochloric acid
Hydrofluoric acid
190 ml
5 ml
3 ml
2 ml
10-30 second immersion. Use only fresh etchant Excellent for aluminum and titanium alloys.
Klemm's Reagent Sodium thiosulfate
solution
Potassium metabisulfite
250 ml Saturated
5 grams
Etch for a few seconds to minutes For etching alpha-beta brass, bonze, tin, cast iron phosphides, ferrite, martensite, retained austenite, zinc and steel temper embrittlement.
Kroll’s Reagent Distilled water
Nitric acid
Hydrofluoric acid
92 ml
6 ml
2 ml

Swab specimen up to 20 seconds
Excellent for titanium and alloys.
Lepito's Etchant Solution A:
(NH4)2 S2O8
Distilled Water;
Solution B:
FeCl3
HCl
Solution C:
HNO3


12.6 grams
42ml

210 grams
84 ml

25ml

Follow mixing directions listed on the product Wrought stainless steel
Marble's Reagent CuSO4
Hydrochloric acid
Water
10 grams
50 ml
50 ml
Immerse or swab for
5-60 seconds.
For etching Ni, Ni-Cu and Ni-Fe alloys and superalloys. Add a few drops of H2SO4 to increase activity.
Murakami's K3Fe(CN)6
KOH
Water
10 grams
10 grams
100 ml
Pre-mix KOH and water before adding
K3Fe(CN)6
Cr and alloys (use fresh and immerse); iron and steels reveals carbides; Mo and alloys uses fresh and immerse; Ni-Cu alloys for alpha phases use at 75 Celcius; W and alloys use fresh and immerse; WC-Co and complex sintered carbides.
Nital Ethanol
Nitric acid
100 ml
1-10 ml
Immersion up to a few minutes. Most common etchant for Fe, carbon and alloys steels and cast iron - Immerse sample up from seconds to minutes; Mn-Fe, MnNi, Mn-Cu, Mn-Co alloys.
Oberhoffers Solution A:
Ethanol,
Distilled water
FeCl3
SnCl2)
Solution B:
Distilled water
HCl


120 ml
5 ml
7.2 grams
0.12 grams

115 ml
10 ml

Use fresh Steels and special steels. Fe-enriched areas appear dark
Picral Ethanol
Picric acid
100 ml
2-4 grams
Seconds to minutes
Do not let etchant crystallize or dry –explosive
Recommended for microstructures containing ferrite, carbide, pearlite, martensite and bainite. Also useful for magnetic alloys, cast iron, high alloy stainless steels and magnesium.
Ralphs etchant Distilled water
Methyl alcohol
HCl
CuCl2
FeCl3
62.5 ml
125 ml
62.5 ml
1.25 grams
4.4 grams
Seconds to minutes Ferritic stainless steels
Schantz Etchant

Solution A:
Distilled water
H2SO4
HCl
FeCl3
Solution B:
HNO3
Distilled water
Solution C:
Acetic acid
Distilled water


5 ml
10 ml
110 ml
17 grams

30 ml
30 ml

40 ml
20 ml
Seconds to minutes Nickel and cobalt
TI-AP-16 SiO2, 43 ml
NH4OH, 16 ml
30% H2O2
432 ml
43 ml
16 ml
Apply to polishing pad, rinse after use Enhances the polishing rates and improves surface finishes for titanium alloys
Vilella’s Reagent Picric Acid
Hydrochloric acid
Ethanol
1 gram
5 ml
100 ml
Seconds to minutes Good for ferrite-carbide structures (tempered martensite) in iron and steel
Waterless Kallings CuCl2, 125 ml HCl, Denatured alcohol 6.25 gm
125 ml
Seconds to minutes Waterless Kalling's reagent; for iron-base and nickel-base superalloys
Weck's 7.5 grams ammonium bifluorides
HCl
Distilled water
4.5 grams
10 ml
240 ml
Seconds to minutes Weck's tint etch for Ti and alloys. Alpha grains and twins colored according to orientation
Winsteards

Picric acid, 10 ml
Ethanol
Distilled water
Surfactant
HCl

2 grams
10ml
200 ml
5 ml
5 drops
Seconds to minutes Low carbon steel - austentic grain boundaries

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