Etching welds

[shortfuse]

In the UK you can Buy Nitric acid, theres some for sale on ebay, not sure of the US, so check there,

as described you need to polish up the cut test piece as best you can and then apply a small blob of the acid, which has been diluted 10% acid to 90% water

Wait a few minutes and then you'll see the fusion/penetration, heres some i did earlier

Very good pictures...I hope my little digital will do macro that well. Hey, Christmas is coming up and a guy always needs a camera in the shop to take macro shots, right?

Nitric acid in the states has gotten to be pain in the *ss. It can be purchased, but I don't need a pint or quart just for small projects. I'll stick with HCl, phosphoric acid (Naval Jelly), ammonium persulfate, etc.

[Gerry1964]

Very good pictures...I hope my little digital will do macro that well. Hey, Christmas is coming up and a guy always needs a camera in the shop to take macro shots, right?

I took them with my Samsung Galaxy S2 8MP Camera Excellent Phone, but don't tell Apple

[shortfuse]

I took them with my Samsung Galaxy S2 8MP Camera Excellent Phone, but don't tell Apple

Man, it's getting to where phone cameras are better than most regular cameras!

Samsung vs. Apple....that thread would be worse than a trailer welding thread

[keithwins]

I'll just say, as someone who's interested in understanding all this, besides some of the silly back and forth I find this thread really interesting, though maybe that's because I haven't seen a lot of etched welds before. They give me a picture of penetration issues that I didn't have. Wirehead that plate weld looks beautiful, at least as far as I can tell.

[shortfuse]

keithwins.....

If you've been following the thread and the links provided by several members, you may have seen what looked like really nice welds. There have been very good links to threads on the forum. Upon examination, the sectioning and etching shows small pits or cracks that appear in the intersection of two plates in a T-joint, for example. Some even show NO penetration of either plate, just fusion on either surface. Looks great on the surface, "stack of dimes", etc., but really aren't good welds. Etching is but one more tool we can use to evaluate our welds and gives us a 3-D view you can't get with a visual, BFH or bender. Since X-ray is out of the question for the average guy, it's a cheap and simple tool.

Not wanting to start a new discussion here, but the "fusion" would be the melting and bonding of the weld with the base metal with no depth of penetration, whereas "penetration" would be melting and invasion of the weld into the base metal providing a much stronger bond.

Here are some clips from one video that sort of shows the comparison between fusion and penetration. Go to the minute mark noted for each type.



Penetration: 18:24 min. Good weld
Fusion: 19:39 Poor weld

Good penetration: http://weldingweb.com/showpost.php?p...4&postcount=38
I've learned a lot from the guys here.

[keithwins]

keithwins.....

Not wanting to start a new discussion here, but the "fusion" would be the melting and bonding of the weld with the base metal with no depth of penetration, whereas "penetration" would be melting and invasion of the weld into the base metal providing a much stronger bond.

Interesting vid. I would have guessed that welding a t-joint, for example, you would seek to have penetration from each side deep enough that they met in the middle and there was no unfused metal surfaces inside the weld. That is clearly not what's shown in that video, nor below. I'm not judging -- I don't know enough to judge -- but it's different than my intuition would have lead me to expect. Thanks for linking that.

[shortfuse]

Interesting vid. I would have guessed that welding a t-joint, for example, you would seek to have penetration from each side deep enough that they met in the middle and there was no unfused metal surfaces inside the weld. That is clearly not what's shown in that video, nor below. I'm not judging -- I don't know enough to judge -- but it's different than my intuition would have lead me to expect. Thanks for linking that.

Those two time clips were just two quickies I was able to come up with to illustrate penetration and the lack of penetration. You can have all depths of penetration up to burn-thru. You can search to your heart's content for pics of various welds and will see many variations, many on this forum as well as youtube.

[Jay O]

I took a look at the video and only the first sample may have been a good canidate to etch but in all the others were unnecessary. The weld discontinuities would have been seen as soon as the sample was being prepped. You included a link to a posting from rickv, in his posting he has a intelligent way of approaching his post. The one thing that Rickv was doing was teaching himself how to weld and people would give him advice and he would ignore it. Overall it seemed like he would grab bits of info from here and there and use it to bolster his post and not realize it was setting him back. The biggest change in Rickv's welding was that he took a welding class.

[N2 Welding]

I know I'm digging up an old thread here but I'm wondering if Shortfuse was able to successfully etch a cut and polished weld.

[motolife313]

Did u cut ur piece out?

[N2 Welding]

Yes cut, sanded and polished with the blue scotchbright pad. I tried the naval jelly and a torch but think I got it too hot. I was not able to see anything. I will try again today. It is a lot of work just to see the weld pen.

[CEP]

Here is how I do it. Make the cut. Sand, and polish the weld area. Brush on the Phosphoric Acid. Wait a minute of two.

[N2 Welding]

I used the same grits as you CEP and below is the closest thing I can find online for Phosphoric Acid. Is the type you have still available?

http://www.homedepot.com/p/Miracle-S...rVHBoCJXHw_wcB

[CEP]

I really don’t know. I can’t remember where I bought it. Maybe ebay!
The guys here, walked me through this a few years ago. Kind of cool to see the penetration of a weld.

[N2 Welding]

They do see it on ebay as food grade and tech-grade. I have not clue what the difference is they are both 85% dilute.

[CEP]

Yes, I bought it off ebay. Post 39 of this thread. I would buy the reagent type, it worked well for me.
http://weldingweb.com/vbb/showthread.php...highlight=etch

[N2 Welding]

Oops I corrected my last post. It was actually food grade and tech grade :/

[N2 Welding]

Ok just got off the phone with the Science Company. Reagent grade is for laboratory testing, food grade has heavy metals and other non safe for human consumption particulates removed for safety and tech grade is the lowest grade which I was told would be good enough for what I am trying to do. The guy on the phone at the Science Company said they sell directly on their web sight.

[CEP]

Here’ some.
http://www.carolina.com/specialty-ch...0-ml/881470.pr

[N2 Welding]

Thank you CEP... I just found some Miracle Heavy Duty Acidic Cleaner in the Garage. I have a crate of bottles of different things/fluids that were being tossed by a lady that I was able to salvage and be used again before it went off to the recycling center.

It looks very similar to the stuff I linked from Home Depot above. I'll give it a try and if it don't work I will order some of that stuff you linked.

[motolife313]

Yes cut, sanded and polished with the blue scotchbright pad. I tried the naval jelly and a torch but think I got it too hot. I was not able to see anything. I will try again today. It is a lot of work just to see the weld pen.

Ya u don't wanna use a torch. I tried it and made a mess. Just buff it back down and then apply the jelly. The heat from the sanding should be enogh. Maybe put it in the oven at 250 for 5 minutes or less

[N2 Welding]

LOL I use to have an old toaster oven I was saving for things like this but I think it ended up getting tossed. It was ruined by an ex who put a candle on top of it then used it with out removing the candle while in use DURR!

I tried the Miracle acid cleaner and no miracles are happening today It kind of looks like it is trying to show the penetration profile but it's hard to tell. I'm not sure if it's the the lighting, my eyes, the used liquid solution, my buffing process, angle of the view or all the above.

Here is what I have after a few minutes with the Miracle cleaner on it.

[N2 Welding]

went back out to garage to redo the buffing to apply the naval jelly and the miracle cleaner was dry and looks like it did an ok job. But I want to be able to clearly see definition between parent metal, weld bead and penetration.

[motolife313]

Looks Like u got well passed the root. Nice job. Now how about some aluminum?

[shortfuse]

I know I'm digging up an old thread here but I'm wondering if Shortfuse was able to successfully etch a cut and polished weld.

Yes, I got a successful etch from a polished weld. No pictures though. Used Naval Jelly. The etch was faint but clearly outlined the penetration. I need to get some more concentrated phosphoric acid, but it would be a thousand years before I used one of the pint or gallon jugs!!!!!