How to check weld penetration. Acids,Bluing,Rusting, What works? My research revealed

[I_Love_Plasma]

For a long time I have been wanting to check my weld penetration like Jody does from "Weldingtipsandtricks.com" "down and dirty tips and tricks" by cutting the weld perpendicularly to the length. So I laid a pretty uniform bead of E7018 on uncleaned A-36 steel. I cut it cross wise with our plasma cutter. Then ground it back about an eighth of an inch or so to grind away from anything the plasma may have fused during the cut. then I smoothed out the angle grinder marks with a flat wheel 80grit. I knew that etching was done with acid. So I decided to try vinegar, it bubbled a little but the steel and the weld didn't change colors. So I carefully dipped a few drips of sulfuric acid from an automotive battery, it bubbled pretty fast, still no color changes. Okay I need a stronger acid! Gingerly I dripped about a cc of Hydrochloric Acid concentrate on the weld surface, it bubbled violently, yet no color changes took place. By now I was wondering how industry did etching so I Googled "How to etch mild steel" and I found out that industry uses nitric-acid. I don't have nitric-acid! I do have some glycerin around somewhere though , for those who know what I'm talking about Nitric-acid is wildly expensive and even worse is the hazmat fee that UPS charges. So I got to thinking about how a member here on the forum removed rust from his old wood jointer by using electrolysis. I knew in electrolysis the positive attracts oxygen molecules and the negative attracts hydrogen molecules. Hydrogen is not corrosive, oxygen is, ha ha watch out! So I reground my weld cross cut, sanded it with a flat wheel from 80 grit to old 220 grit. Then I used some mag wheel pumice polish on it until I could see myself in the reflection. Now I took the piece and placed it in a strong solution of drain cleaner (100% pure sodium lye, potassium lye works just as well). And made the welded piece positive with our 12amp 12VDC battery charger on the "manual charge" setting. I placed the weld surface into the electrolyte about a sixteenth of an inch, and a piece of 316L Stainless Steel on the other side as my negative electrode. This method works great!

Here are some pictures of the cross cut weld after about 30 minutes of electrolysis.
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The cost is basically free, especially compared to about $50-100 dollars for a tiny bottle of nitric-acid.

USE EXTREME CAUTION WHEN ELECTROLYSIS IS OCCURRING! HYDROGEN AND OXYGEN GASES CAN BUILD UP CAUSING A POTENTIALLY FATAL EXPLOSION IF THE GASES ARE IGNITED! IT TAKES A 14 NANO JOULE SPARK TO SET OFF HYDROXYL GAS (MUCH LESS THAN A LIGHTER, OR A BRUSHED MOTOR PRODUCES)! BE SAFE!

Post comments, tips, thoughts, and questions,
I Love Plasma!

[sportbike]

You can try Muriatic acid (which is actually Hydrochloric acid), available at hardware stores in fairly high concentrations for cleaning concrete. It might take awhile for the etching to occur, but it should give you the results you are looking for. Just put a bit in a plastic tub and let teh polished edge of teh steel sit in it. Give it a look every half hour or so and pull it out when you like the results. Don't leave in in overnight or for a very long time as it may burn out and you will ave to re-polish to get it to be visible again.

You can also try Ferric Chloride mixed with water as an etchant, but the Muriatic acid is pretty easy to pick up at a hardware store.

This won't work with aluminum by the way.

[I_Love_Plasma]

Thanks for the suggestions. I think I might try finding some Ferric Chloride. As far as Hydrochloric acid goes; I have the strongest commercial concentration available. It's 36% Hydrochloric, 61% Muriatic, and 3% water, if the label is correct.

My process only took 30 minutes, and soon I will be trying just grinding it smooth and not sanding/buffing it to a mirror finish. HAHA I should have taken a picture before, it looked like a piece of a SS exhaust tip.


ILP

[sportbike]

Thanks for the suggestions. I think I might try finding some Ferric Chloride. As far as Hydrochloric acid goes; I have the strongest commercial concentration available. It's 36% Hydrochloric, 61% Muriatic, and 3% water, if the label is correct.

My process only took 30 minutes, and soon I will be trying just grinding it smooth and not sanding/buffing it to a mirror finish. HAHA I should have taken a picture before, it looked like a piece of a SS exhaust tip.


ILP

Hmm...didn't see that you tried hydrochloric. That should have worked.

I think you will find that the smooth finish is desirable. It really has nothing to do with the etching itself, but the issue is, the details in the etched surface will not be very visible.

[I_Love_Plasma]

I took that same piece, ground it back again all good and shiny. I used a 3" cutoff wheel to do quick de-burring of the surface. Placed it in the electrolysis solution turned it on and 20 minutes later I came back and I could plainly see the weld bead was discolored, setting off the line in between the two metals. So A> You don't have to smooth it to a mirror, but it looks better in the final product. B> It doesn't take nearly as long as acid, though acid does work. But who is going to have extremely high concentration's of Hydrochloric acid sitting around? Now drain cleaner or baking SODA (not powder lol) or table salt can be used as electrolyte. Lye is the best.

Next I am going to leave the surface rough right off the angle grinder to see if I can still see the weld.

Also,
I would like to add, that Mark (Performance) said to me on the phone; "You will find it more useful, skill wise, to cut the weld in half, length wise. This will show porosity and you will see how good your starts and stops are. Or if you have pockets of flux or worm holes ..." Thank you Mark.

Stay safe,
ILP

[donor76]

When I worked at factory caterpillar, I every month welded samples, then them sawed, polished and poisoned (if to me doesn't change memory) sulfuric acid (all was shown instantly)

[I_Love_Plasma]

When I worked at factory caterpillar, I every month welded samples, then them sawed, polished and poisoned (if to me doesn't change memory) sulfuric acid (all was shown instantly)

I'm sorry, I am having difficultly comprehending what you said. But if you used sulfuric acid and it showed up right away, maybe my battery acid is real weak..

This morning's findings,
I reground the piece I have been using to test methods. I just used our angle grinder, I didn't smooth it or de-bur the piece at all. I can still clearly see the weld nugget/bead. And I found it takes roughly 5 minutes at 6-8amps/12VDC for the weld bead to show up.


ILP

[Joe from NY]

I'm sorry, I am having difficultly comprehending what you said.
ILP

Remember donor76 is in Russia, and may or may not be using a translation program to post. For example his "if to me doesn't change memory" most likely means "if my memory serves me correct". It is great how a forum enables brothers on the other side of the planet with different languages to communicate and help each other.

[Tritium]

A solution of nitric acid and alcohol, Nital, is used for etching of metals to reveal the microstructure. ISO 14104 is one of the standards detailing this well known procedure.

http://en.wikipedia.org/wiki/Nital

Thurmond

[redbeard]

Remember donor76 is in Russia, and may or may not be using a translation program to post. For example his "if to me doesn't change memory" most likely means "if my memory serves me correct". It is great how a forum enables brothers on the other side of the planet with different languages to communicate and help each other.

I believe he did mention using Google translate in another post. It really does do a surprisingly good job.

I second the salute to technology that unites us all around the globe.

[donor76]

Yes my friends, I communicate with you through Google the translator (excuse for inconveniences)

[Joe from NY]

Брат, мы рады видеть вас здесь. the interwebs are awesome! just think about what we were doing 30 years ago. i certainly am more educated on a multitude of subjects now, and i have a lot more crap that i impulsively ordered. Back then, if it wasn't in the Sears catalog, or the Northern Hydraulics catalog, i didnt know about it and couldn't buy it.

[donor76]

Guys happy New Year!!! ура!!!

[Joe from NY]

Donor- was my Russian translation correct, what did it say?

[donor76]

I rejoice(on Russian)

[Joe from NY]

I rejoice(on Russian)

Is that what the Russian translated to?

[zoama]

Is that what the Russian translated to?

He understood your welcome but he can't tell you any better than you tell him through a translator. Translating a translation is like stacking tolerances, it just gets further off the mark. We're really taking this thread off topic.

[I_Love_Plasma]

A solution of nitric acid and alcohol, Nital, is used for etching of metals to reveal the microstructure. ISO 14104 is one of the standards detailing this well known procedure.

http://en.wikipedia.org/wiki/Nital

Thurmond

Thank you for the link Thurmond!

We're really taking this thread off topic.

Thank you Zoama

To all,
please keep this thread on topic. I do agree with Google translator working quite well, I even have it favorited. Welcome to our Russian brother Again please keep it on topic.

Thank you,
ILP

[I_Love_Plasma]

Some new pictures of etching. A-36 steel with 4 passes of 1/8" E7018-1. First pass was 84amps, second pass was 112 amps, third and fourth passes were 134 amps. My technique and amperage must have been lacking, as you can see from the pictures there is not a lot of penetration.

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