Etching steel questions

Greetings all you chemical type folks,
I would like to know what the penetration really is when welding with
the Lincoln SP125 Plus welder. TIG too. I have tested the welds with
the mechanical method. I have also sawn through the welds and looked
at them. But apparently etching will show not only the weld
penetration but also the Heat Affected Zone (HAZ). I'm not sure that
when sawing through the weld it's the weld metal I see or the HAZ. The
only recipe for steel I've found is made from nitric acid and
methanol. Sometimes the nitric acid is called "fuming nitric acid". I
already have the "fuming nitric acid", I bought for passivating small
prototype stainless steel parts. A little of the stuff goes a long
way. Even though I follow ALL the proper precautions when using the
stuff, including proper disposal methods, it still makes me nervous to
use it. On top of that I'd need to buy a gallon of methanol. I use
denatured ethanol (less than 4% methanol) as a solvent for some things
since it's much less toxic than MEK and 100% methanol. So, is there
another etchant for steel that is less dangerous than the nitric
acid/methanol solution? Would ferric chloride work? It doesn't need to
be fast, it just needs to be able to show where the weld stops and the
parent metal starts, and the HAZ.
Thanks,
Eric R Snow
Reply to
Eric R Snow
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In the back of the Lincoln Procedure Handbook there are several recipes. For general macroscopic examination they suggest Ferric Chloride and concentrated Nitric Acid. They suggest rinsing with water then "swab with methyl alcohol to speed drying and inhibit rusting". I imagine the alcohol in your recipe is doing the same thing? Randy
Greetings all you chemical type folks, I would like to know what the penetration really is when welding with the Lincoln SP125 Plus welder. TIG too. I have tested the welds with the mechanical method. I have also sawn through the welds and looked at them. But apparently etching will show not only the weld penetration but also the Heat Affected Zone (HAZ). I'm not sure that when sawing through the weld it's the weld metal I see or the HAZ. The only recipe for steel I've found is made from nitric acid and methanol. Sometimes the nitric acid is called "fuming nitric acid". I already have the "fuming nitric acid", I bought for passivating small prototype stainless steel parts. A little of the stuff goes a long way. Even though I follow ALL the proper precautions when using the stuff, including proper disposal methods, it still makes me nervous to use it. On top of that I'd need to buy a gallon of methanol. I use denatured ethanol (less than 4% methanol) as a solvent for some things since it's much less toxic than MEK and 100% methanol. So, is there another etchant for steel that is less dangerous than the nitric acid/methanol solution? Would ferric chloride work? It doesn't need to be fast, it just needs to be able to show where the weld stops and the parent metal starts, and the HAZ. Thanks, Eric R Snow
Reply to
R. Zimmerman
It won't show as nicely but I have used a chop saw to make a super fine cut (no need to polish), and then dip it in common muriatic acid. $3/gallon at a home or pool supply store.
Eric R Snow wrote:
Reply to
RoyJ
I dunno Randy. Maybe that's just what the alcohol is for. If methyl works why not ethyl? Big booms? Poison gas? Eric
Reply to
Eric R Snow
Thanks Roy, I have some of that acid already. And I'm more comfortable using it than nitric. Eric
Reply to
Eric R Snow
It's very slow, make take several hours. You won't get enough etching to see the grains, but you should be able to see a change in structure which is all you are looking for.
Eric R Snow wrote:
Reply to
RoyJ
Fuming nitric? No!
5% of dilute nitric (normal or thereabouts) in ethanol, methanol, or just about any mixture should do the trick. If it etches too fast, either dilute it more or swab it on then wash it off with alcohol from a squeezy bottle. A bit on your fingers for a few seconds won't do any damage, just rinse it off when you are done. Apart from diluting the acid, the alcohol helps to remove grease. Wipe it on using a bit of cotton wool.
Reply to
Newshound
Newshound, The recipe calls for fuming nitric, distilled water, and methanol. Are you sure ethanol is OK? If so why would all the recipes call for methanol? Maybe all I've are based on the same one? Thanks, Eric
Reply to
Eric R Snow

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