Do you know any metallography etching data base?

[Soldador]

Does anybody know a metallography etching web site ?

I am trying to etch a dissimilar welding (monel-304L). I have already tried cromic, nitric-hydrocloric-acetic, nitric-acetic,and oxalic. but the results were not good. Some of them preferencialy attack the grain boundary or the interdentritic zones. Therefore the microstructure is not clearly developed.
please, could anybody help me?

Thank You.

 

[TVP]

http://www.metallography.com

is a good website for this type of information. Check the archives or post a new question. Experts from Struers and Buehler frequently reply here, so I highly recommend you check it out.

Have you tried electropolishing? Phosphoric acid (H₃PO₄) in glycerol and water is used for both of these alloys. The current density recommendation in ASM HANDBOOK Volume 3 Metallography and Microstructures is a little different, but you may find it useful:

solution:
37 mL H₃PO₄
56 mL glycerol
7 mL water

For stainless steel, the recommendation is 0.78 A/cm² at 100-120 C for 5-10 minutes. For monel, the recommendation is 0.9-1.0 A/cm². Good luck.