what are the etchants available for revealing grain-boundaries and carbide formation along it for Austenitic SS321? Is there any way to optimize these etchants to get more clear microstructure so that more microstructural changes can be revealed?
100 ml destiled water and 10 g Oxalacid is an usually etchant for this type of Steel. Use about 6V from 15 to 60 sec, electrolytic etching. With Short Time you will develop carbides than at longer times GBs. Pls take care for Safety and environmental requirements when you deal with etchants.
Buehler Company has some practical preparation guidelines reported, editier and Supporten by George F. Vander Voort. ISBN 0-9752898-0-2.
I guess G F Vander Voort has a Website, Pls Check for its Metallography Support he give with this Site.
Www.georgevandervoort.com
The option given by Johann Angeli is excellent. However, if you need other look at the attached file .
etched at 5 V in a 60 vol. % nitric acid solution for tens seconds. Please take care for safety.
Thanks a lot to everyone for valuable information. And i want to say that i did try to etch SS321 that is sensitized with aqua-regia ,the samples which were not so long at sensitization temperature did not showed the very clear microstructure this must be due to not much much effect of sensitization for shorter duration. i just want to ask can i get much more contrast than earlier micrographs by means of electrolytic etching??
Hi again. Yes the attack of the etchant depends on chemical and structural inhomogenities. This means your observed experience is in line with theory. Usually longest etching time may help.
another idea: pls use interference constrast with your LOM, if this technique is attached. So you could check microstructure maybe without need of etching your sample. Diiferent grain orientation and hard phases (the carbides) should be feasible to display.
good look
Electrolytic etching with oxalic acid helps you to resolve. Fine tune your etching parameters depending on your sample
- Badges
- Science topic