Et Chants

Etchants

EtchantsAluminum and Aluminum Alloys Brass and Bronze Alloys Cast Iron Copper Alloys Low Carbon Steel High Carbon Steel Stainless Steel Tin AlloyZinc Alloy

EtchantCompositionConc.ConditionsCommentsASTM No. 30AmmoniaHydrogen Peroxide (3%)DI Water62.5 ml125 ml62.5 mlMix Ammonia and water before adding peroxide. Must be used fresh. Swab 5-45 secondsFor etching copper, copper alloys and copper-silver alloys.Adler EtchantCopper ammonium chlorideHydrochloric acidFerric chloride, hydrated DI Water9 gramsl150 ml45 grams 75 mlImmersion is recommended for several secondsFor etching 300 series stainless steel and other superalloysKalling's No. 2CuCl2Hydrochloric acidEthanol5 grams100 ml100 mlImmersion or swabbing etch at 20 degrees CelsiusFor etching duplex and 400 series stainless steels and Ni-Cu alloys and superalloys.The following table lists the most commonly used etchants EtchantCompositionConc.ConditionsCommentsKlemm's ReagentSodium thiosulfatesolution Potassium metabisulfite250 ml Saturated5 gramsEtch for a few seconds to minutesFor etching alpha-beta brass, bonze, tin, cast iron phosphides, ferrite, martensite, retained austenite, zinc and steel temper embrittlement.Krolls ReagentDistilled waterNitric acidHydrofluoric acid92 ml6 ml2 ml

Swab specimen up to 20 secondsExcellent for titanium and alloys. NitalEthanolNitric acid100 ml1-10 mlImmersion 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.Marble's ReagentCuSO4Hydrochloric acidWater10 grams50 ml50 mlImmerse or swab for5-60 seconds.For etching Ni, Ni-Cu and Ni-Fe alloys and superalloys. Add a few drops of H2SO4 to increase activity.The following table lists the most commonly used etchants EtchantCompositionConc.ConditionsCommentsMurakami'sK3Fe(CN)6KOHWater10 grams10 grams100 mlPre-mix KOH and water before adding K3Fe(CN)6Cr 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.PicralEthanolPicric acid100 ml2-4 gramsSeconds to minutesDo not let etchant crystallize or dry explosiveRecommended for microstructures containing ferrite, carbide, pearlite, martensite and bainite. Also useful for magnetic alloys, cast iron, high alloy stainless steels and magnesium.Vilellas ReagentPicric AcidHydrochloric acidEthanol1 gram5 ml100 mlSeconds to minutesGood for ferrite-carbide structures (tempered martensite) in iron and steelThe following table lists the most commonly used etchants Aluminum and Aluminum Alloys

Aluminum alloys are designated as either wrought or cast. Wrought aluminum alloys are classified by the major alloying element 1000 series pure aluminum (1050, 1060, 1199)2000 series aluminum copper alloys (2014. 2024, 2219)3000 series aluminum ma managese alloys (3003, 3004, 3102)4000 series aluminum silicon alloys (4041)5000 series aluminum magnesium alloys (5005, 5052, 5083, 5086, 5154, 5356, 5154, 5356, 5454)6000 series aluminum magnesium and silicon alloys (6060, 6061, 6063, 6066, 6070, 6082, 6105, 6162)7000 series aluminum zinc alloys (70005, 7022, 7068, 7072, 7075, 7079, 7116, 7129, 7178)8000 series aluminum lithium alloys Cast aluminum alloys are classified similarly to wrought alloys, however, the 2nd and 3rd digit signify the percentage of aluminum

1xx.x series are minimum 99% aluminium2xx.x series copper (201.0, 204.0, 242.0)3xx.x series silicon, copper and/or magnesium (319.0, 328.0, 328.0, 355.0, 356.0)4xx.x series silicon (433.3)5xx.x series magnesium (512.0, 514.0, 520.0, 535.0)7xx.x series zinc (705.0, 707.0, 710.0, 713.0, 771.0)8xx.x series lithiumThe most common etchants for aluminum are Kellers etch and Kroll's reagent, however, there are hundreds of more specific etchants. A good resouce for additional etchants can be found with the etchant database provided by PACE Technologies, http://www.metallographic.com/Consumables/Etch.htmSample Preparation: Aluminum alloys must be properly prepared to reveal the true metallographic microstructure. A number of recommended procedures can be found at the following links:http://www.metallographic.com/Procedures/Aluminum%20Description.htmhttp://www.metallographic.com/Brochures/Met-Manual-2b.pdf

CAUTION: Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacturers MSDS. Also review COMMENTS Section for each etchant.

Aluminum-Silicon Alloy, Kellers etch, 200X Brass and Bronze Alloys

The most common etchants for brass and bronze alloys contain either ammonium hydroxide, nitric acid or ferric chloride, however, there are hundreds of more specific etchants. A good resouce for additional etchants can be found with the etchant database provided by PACE Technologies, http://www.metallographic.com/Consumables/Etch.htm Sample Preparation: Brass and bronze alloys must be properly prepared to reveal the true metallographic microstructure. A number of recommended procedures can be found at the following links:http://www.metallographic.com/Procedures/Copper%20Description.htmhttp://www.metallographic.com/Brochures/Met-Manual-2b.pdfCAUTION: Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacturers MSDS. Also review COMMENTS Section for each etchant.

EtchantConc.ConditionsCommentsAmmonium hydroxide (dilute solutions)DiluteImmersionAttack polishing, ASTM 30 is also a good etchant for copper and coper alloysCopper No. 1Distilled water Ferric chloride Hydrochloric acid

200 ml 10 grams 50 mlImmersion or swabbingBrasses, bronzes, aluminum brass, alpha -phases in brassCopper No. 2Nitric acidDistilled water

125 ml 125 ml1 second to several minutes by immersion or swabbingCommon etchant for copper and copper alloys such as brass and bronze

Manganese-Aluminum Bronze Alloy, 400X DIC) EtchantConc.ConditionsCommentsNital Ethanol Nitric acid100 ml 1-10 mlSeconds to minutesDo not exceed 10% nitric acid - explosive Cast Iron

CAUTION: Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacturers MSDS. Also review COMMENTS Section for each etchant.

Copper Alloys

The most common etchants for copper alloys contain either ammonium hydroxide, nitric acid or ferric chloride, however, there are hundreds of more specific etchants. A good resouce for additional etchants can be found with the etchant database provided by PACE Technologies, http://www.metallographic.com/Consumables/Etch.htm Sample Preparation: Copper alloys must be properly prepared to reveal the true metallographic microstructure. A number of recommended procedures can be found at the following links:http://www.metallographic.com/Procedures/Copper%20Description.htmhttp://www.metallographic.com/Brochures/Met-Manual-2b.pdfCAUTION: Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacturers MSDS. Also review COMMENTS Section for each etchant.

EtchantConc.ConditionsCommentsDistilled water Ammonium hydroxide Hydrogen peroxide (3%)25 ml 25 ml 5-25 mlSeconds to minutes (use only fresh)-Grain boundaries use less H2O2-Grain contrast use more H2O2Distilled water Nitric acid50 ml 50 mlSeconds to minutesCopper and copper alloysDistilled water or Ethanol Hydrochloric acid Ferric chloride100-120 ml 25-50 ml 5-10 gramsSeconds to minutesProduce grain contrast

Low Carbon Steel Etchants

The most common etchant for low carbon steels or weld steels is Nital, however, there are a lot of other potential etchant for speicalized etching. A good resouce for additional etchants can be found with the etchant database provided by PACE Technologies,

http://www.metallographic.com/Consumables/Etch.htm Sample Preparation: Low carbon steels and welded steel must be properly prepared to reveal the true metallographic microstructure. A number of recommended procedures can be found at the following links:

http://www.metallographic.com/Etchants/Low%20carbon%20steel%20etchants.htmhttp://www.metallographic.com/Brochures/Met-Manual-2b.pdf

CAUTION: Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacturers MSDS. Also review COMMENTS Section for each etchant.

EtchantConc.ConditionsCommentsNital Ethanol Nitric acid100 ml 1-10 mlSeconds to minutesDo not exceed 10% nitric acid-explosive Picral Ethanol Picric acid100 ml 2-4 gramsSeconds to minutesDo not let etchant dry-explosive

1018 Low Carbon Steel (quenched), etched, Mag. 100X High Carbon Steel Etchants

The most common etchants for heat treated steels or martensitic microstructures contain picric acid dissolved in alcohol and acids. A good resouce for additional etchants can be found with the etchant database provided by PACE Technologies, http://www.metallographic.com/Consumables/Etch.htm Sample Preparation: Both heat treated and un-heat treated steels must be properly prepared to reveal the true metallographic microstructure. A number of recommended procedures can be found at the following links:http://www.metallographic.com/Procedures/Steel%20Description.htmhttp://www.metallographic.com/Brochures/Met-Manual-2b.pdfCAUTION: Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacturers MSDS. Also review COMMENTS Section for each etchant.

EtchantConc.ConditionsCommentsPicral Ethanol Picric acid100 ml 2-4 gramsSeconds to minutesFor heat treated steelsDo not let etchant dry-explosive Ethanol Nitric acid Hydrochloric acid Picric acid80 ml 10 ml 10 ml 1 gramSeconds to minutesGrain boundariesNital Ethanol Nitric acid100 ml 1-10 mlSeconds to minutesDo not exceed 10% nitric acid -explosive

1095 High Carbon Steel (furnace cooled), etched, Mag. 100X http://www.metallographic.com/Etchants/Etchants.htm