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:
CAUTION: Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacturers SDS (Safety Data Sheets). Also review COMMENTS Section for each etchant.
|Seconds to minutes||Do not exceed 10% nitric acid-explosive|
|Seconds to minutes||Do not let etchant dry-explosive|