as per advise of some of you I tried to do some cut and etching on my welds to check for penetration and I cant get it to etch. I bought this rustoleum rust remover which is similar to naval jelly, they both have phosphoric acid. So i did some welds cut em, then applied the jelly, waited a while, tried some heat, tried agitating hit, waited longer, tried just about everything, and nothing.
Buuut here is where the twist is, i took another piece i cut and tried one more time, being lazy and frustrated i didn't buff or polish this one, just ground down with a dremel tool, and it worked!* It worked in only about a minute and I saw a fairly clear out line of the weld and saw I didn't get much penetration in the root but good on the toes, so i tweaked my settings and technique slightly and went to try it again, and for the life of me I can't get it to work again. I tried to recreate everything I did, I tried buffing and polishing again, I tried heat again. I don't know how I did it but I can't get it to happen again. Any ideas?
Lab Procedure- Etching Steel Specimens Note: Always wear Acid Resistant gloves when Etching! 1. Place the specimen on the table under the Fume Hood with the polished surface up. 2. Turn on the Fume Hood. 3. Without touching the specimen surface, clean the surface with alcohol and let it dry using the hot air gun. Do not let anything but the alcohol touch the specimen surface! 4. Using the Eye-Dropper, apply a few drops of Etchant to the specimen surface covering the entire metallic surface of the specimen. 5. After about 20 to 30 seconds, rinse the Etchant into the sink with water and quickly rinse the specimen with alcohol, but do not touch the surface! 6. Use the Hot Air Gun to dry the sample. 7. Proceed to Microscopic Examination; if further etching is required you may return and proceed through steps 1 through 6 varying the time in step 5 depending on the results. 8. If the specimen has many scratches and marks or the microstructure cannot be seen after several etches, return to fine grinding and go back through the necessary steps.
Stolen from here. Did this in college and I remember needing to stain some of the samples with (I don't remember - iodine?) to get a better contrast.
https://youtu.be/8DPhc5K_thg
This is the procedure that i use when teaching. I also use the Welding Tips and Tricks videos in my class. Please post some photos of the etched welds. Also feel free to contact me by email text or phone.
Braden
