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Metallographic Stainless Steel Etchants

Etching stainless steels can be somewhat difficult due to the anti-corrosive nature of stainless steel. Austenitic or 300 series stainless steels typically have higher chrome as well as a significant amount of nickel (e.g. 304 stainless steel - 18% chrome, 8% nickel) which makes them harder to etch. Martensitic or 400 series stainless steels are easier to machine, however, they are not as corrosion resistant so they are easier to etch.

PACE Technologies Etchant Database Click here to get order

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.

Sample Preparation:
Stainless steels must be properly prepared to reveal the true metallographic microstructure. A number of recommended procedures can be found at the following links:

PACE Technologies Recommended Preparation for Stainless Steel PACE Technologies Metallographic MET-MANUAL Link
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Recommended Etchants
Etchant Conc. Conditions Comments
Adlers Etchant

Ferric chloride
Copper ammonium chloride
Hydrochloric acid
Distilled water

45 gm
9 gm
150 ml
75 ml
Immerse for several seconds. A very effective etchant for 300 series, austenitic, duplex stainless steels
Carpenter Etchant

Ferric chloride
Cupric chloride
Alcohol
Hydrochloric acid
Nitric acid

8.5 gm
2.4 gm
122 ml
122 ml
6 ml
Immerse for several seconds. A nice etchant for 300 series, austenitic, duplex stainless steels
Kalling' No. 2

Cupric chloride
Hydrochloric acid
Alcohol

12 gm
20 ml
225 ml
Immerse or swab - seconds to minutes For 400 series or martensitic stainless steel
Modified Murakami's

K3Fe(CN)6
Potassium hydroxide
Distilled water

30 gm
30 gm
150 ml
1 second to several minutes by immersion or swabbing

Mix potassium hydroxide into water before adding K3Fe(CN)6

Hydrochloric acid
Selenic acid
Ethyl alcohol
20-30 ml
1-3 ml
100 ml
Immerse at room temperature for 1-4 minutes Color etching. Colors carbides and gamma prime phase in heat resisting steels
Ammonium bifluoride
Potassium metabisulfite
Distilled water
20 gm
0.5 gm
100 ml
Immersion at room temperature for 1-2 minutes Color etching. Etching of austenitic stainless steel and welds. Reveals delta ferrite in welds
V2A Etchant

Hydrochloric acid
Nitric acid
Distilled water

119 ml
12 ml
119 ml
Immersion or swabbing etch at 20 degrees Celsius

For etching austentic stainless steels

Wecks No. 2 Reagent


Potassium Permanganate
Sodium Hydroxide
Distilled water

25 gram
25 grams
250 ml
Immersion or swabbing etch at 20 degrees Celsius

Often used for stainless steels, nickel-based alloys, and sometimes other metals to reveal grain boundaries, phases, and other microstructural features


Metallographic micrograph of etched stainless steels
431 Stainless Steel, etched with Modified Murakami's,
Mag. 400X (DIC)

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