Looking for an etchant for low heat welds

Date 01-20-2016 20:05

Hey all,

Working in the lab out here and running into an issue with low heat welds showing up after etch. We do all sorts of welds and materials and different etchants. Now we run into the occasional problem with very low heat welds that don't change the grain structure enough for proper contrast. I saw the earlier thread showing G.S. Crisi's magical etch hoping that it would be what I needed. Although it was a great etch and has now kept us from needing electrolysis on nickle based alloys, it does not effect low heat welds.

We currently have ran into two welds that didn't show up no matter what we did. we had to evaluate them on the actually coverage we could see and the faint outer nugget edge that did happen to show through. One of them being a small titanium tube groove on a 1/4" tube. We etched and faintly got a more aggressive grain structure in the weld zone but no definite edge location. The second, and the reason I putting this out there is we received a small Resistance Seam weld on aluminum and the heat was so low we cant see a damn thing. I figure the grains are so hardly effected that they are providing no real contrast.

So if any of you may know a solution it would be greatly appreciated!

J. Maxwell

By Trackergd (**)

Date 01-20-2016 23:58

Here are some suggestions. On steel I use a 10% Nytol solution which I apply with a Q-Tip until I can see the contrast, then I rinse off and dry the sample. I then use Navel Jelly on a Q-tip with a circular motion, then wipe off with a soft cloth, but do not rinse off. You can also try the Navel Jelly alone. The Navel Jelly is both an etchant and prevents rust from forming before I can photograph the sample.

On the aluminum, I use the yellow can Easy Off oven cleaner...I only leave it on for a short time, then rinse off and dry. I get great results with this method.

Hope some of this helps.

By MRWeldSoCal (***)

Date 01-21-2016 16:27

Very interesting, Ill send my guy out from some oven cleaner, and look into getting the other supplies.

Thanks you for the input

J

By Trackergd (**)

Date 01-22-2016 14:42

Let me know if any of them work out for you. I am curious about the results you get.

Yesterday I used the Navel Jelly alone for a carbon steel weld and it worked great, not as dark as Nytol, but good enough to see the lack of penetration issue and show the welders...of course the toe crack should have been their first clue... :roll:

By MRWeldSoCal (***)

Date 02-01-2016 21:23

Ok so were back to having very thin foils to etch. we have .003" Inconel Foils RESW welded. We are having trouble getting the nugget to pop. We used out electrolysis as well as another etch we use and cant get a nugget to show up at all. We ran longer times as well.
The etch we used for electrolysis is a 70% Nitirc and 30% methanol. Usually works fine with any inco, SS, that we see.

J