Halcohead
Stainless
- Joined
- Apr 10, 2005
- Location
- Bay Area, Ca
Has anyone here done in-house metallography on aluminum? Any tips for sample prep and a (relatively) safe etching solution?
I have a number of weld specimens in 1/16" aluminum I'd like to do metallography on to examine grain structure and look for voids and areas of poor bonding. There are strong reasons to believe these defects are there, however my current attempts at polishing have not revealed any, even under 40x magnification.
So far I've milled the sample with a sharp endmill, then used progressively finer sandpaper up to 3 micron to clean up the surface. There is a fine polish at this point with minimal scratches. For some reason when I go to 1 micron I get severe scratching, even with brand new sheets. The sheets are backed by a surface plate.
So far haven't messed with etching since I every etchant I've found includes HF, which I'm not equipped to handle (and don't want to be). Would regular hydrochloric acid be sufficient to reveal grain structure and defects?
Of course I can send samples out, but lead times are 2-3 weeks which really slows development.
I have a number of weld specimens in 1/16" aluminum I'd like to do metallography on to examine grain structure and look for voids and areas of poor bonding. There are strong reasons to believe these defects are there, however my current attempts at polishing have not revealed any, even under 40x magnification.
So far I've milled the sample with a sharp endmill, then used progressively finer sandpaper up to 3 micron to clean up the surface. There is a fine polish at this point with minimal scratches. For some reason when I go to 1 micron I get severe scratching, even with brand new sheets. The sheets are backed by a surface plate.
So far haven't messed with etching since I every etchant I've found includes HF, which I'm not equipped to handle (and don't want to be). Would regular hydrochloric acid be sufficient to reveal grain structure and defects?
Of course I can send samples out, but lead times are 2-3 weeks which really slows development.