The sample showed processed by SLM shows differential etching with respect to surface and the bulk. The cross-sectional samples after the deposition are etched. What could be the reasons for the same?
The Inconel alloy is built on Iron substrate using SLM process, for a thickness of 2 mm and 5 mm width.
On etching the cross-section, the surface regions get etched quickly compared to the bulk. To see the bulk microstructure, I have to over-etch the surface part. Is there any other alternatives for etching superalloys uniformly?
You may possibly want to check this previous RG discussion: https://www.researchgate.net/post/What_is_the_best_type_of_etchant_to_observe_Inconel_625_weld_microstructure
For SLM parts, I can see that compared to the bulk layer closed to the Iron substrate, the top surface layer has significant different microstructure due to cooling rate differences , i.e. different etching rates. You can try to use diluted etchants and mask the surface.