j_sum1
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Composition of some tool steels
I was going to post this in the short questions thread but figured that I could probably benefit from a bit f discussion on it.
I have inherited some tools and have been tidying out my shed. I have a lot of tools that are surplus to requirements and was wondering about
interesting things that I might do with them: specifically seeing if I can digest them in a bucket of acid and isolate some chromium, molybdenum and
vanadium compounds from them.
So, as a start point I need to have some idea what these metals are made of.
(Lest anyone freak out most of the throw-out tools are of the cheap and nasty variety and/or have suffered a lot of wear or rust. I am keeping the
brand-name stuff.)
I have a significant pile of driver bits. Many are rusted.
I have a bunch of drop-forged spanners. (Wrenches in US parlance.)
I have a handful of sockets.
I have a large box full of drill bits. Most are probably quite functional but it is far more practical for me to reach for one from a set where I
know what size it is.
Does anyone have an idea of the typical compositions for these?
If I was to guess, I would say Fe/V for the drivers, Fe/Cr/Ni for the wrenches and sockets with maybe a bit of Mo. I suspect the drill bits have
comparatively low levels of alloying agents and are probably a bit of a mix. But this is all a guess. My preliminary searches brought up lots of
conflicting information and nothing particularly definitive.
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bobm4360
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Most drill bits, even the cheap ones, are made from "high-speed" steel, usually W and Mo are the alloying elements, occasionally Co. Should be some
interesting separations.
Bob
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Melgar
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For stainless steel, you can dissolve it in 10-25% hydrochloric acid. For other steels, dilute sulfuric acid works better since it's a stronger acid,
and you can tell when your acid concentration is too high, or your water concentration is too low, if you start smelling sulfurous odors from your
acid solution. You can add hydrogen peroxide to either acid to speed up the dissolution, but you have to be extremely careful that it doesn't get so
hot that the H2O2 exceeds its thermal decomposition temperature, which will result in an eruption of boiling acid. It's good to have some cold water
on hand to use to cool your flask if you notice it starting to get hot. With HCl, you shouldn't add peroxide immediately, because that results in the
release of chlorine gas, but as the metal dissolves and the chloride concentration gets higher, that increases the solution's ability to dissolve
chlorine, forming Cl3- ions, which are strongly oxidizing.
I prefer using sulfuric acid to dissolve exotic steels though, because that forms iron (ii) ions, which are pale blue in solution, compared to iron
(iii) ions, which are dark yellow to brown at high concentrations. So if you use HCl to dissolve steel, you won't be able to distinguish the other
salts' colors very well at all, because of how dark-colored iron (iii) salts are.
You also have to deal with carbon particles coating the surface of steel and stopping it from dissolving. You can periodically filter the solution,
take out the metal, torch it until it glows, which should burn off any exposed carbon, then put it back into the acid. The black precipitate at the
bottom will probably be mostly carbon, but you should also try burning that to see if anything gets left behind. There might be small quantities of
other metals or their salts that aren't water-soluble.
To separate metals, electrorefining might be an option, but you'd need to use a divided cell to account for all the metals that have multiple
oxidation states, especially iron, which easily transitions between +2 and +3. Ideally, you'd figure out a way to remove the iron specifically, so
you can focus your energies on the other metals. I haven't done this personally though, so I won't speculate.
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j_sum1
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All good advice. Thanks Melgar.
I have a procedure for Cr from stainless -- basically following in the footsteps of Tdep (extractions and ire).
But I thought I might target the vanadium first. Not that I have done a whole lot of reading and research yet but I thought dissolving in HCl (HCl is
far more accessible to me than H2SO4) and then making alkaline with NaOH I might precipitate a lot of Fe and other stuff and have a solution
containing sodium metavanadate.
But as a first step I wanted to know what other species I might need to navigate around. If there is Co, Ti or Ni there, that may make things more
complex. And obviously I will get nowhere if I choose a steel with no vanadium at all.
So. Does anyone actually know what they make driver bits out of?
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NedsHead
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driver bits are probably made cheaply from plain, high carbon steel and then heat treated. That would be my guess anyway
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Melgar
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Quote: Originally posted by j_sum1  | All good advice. Thanks Melgar.
I have a procedure for Cr from stainless -- basically following in the footsteps of Tdep (extractions and ire).
But I thought I might target the vanadium first. Not that I have done a whole lot of reading and research yet but I thought dissolving in HCl (HCl is
far more accessible to me than H2SO4) and then making alkaline with NaOH I might precipitate a lot of Fe and other stuff and have a solution
containing sodium metavanadate.
But as a first step I wanted to know what other species I might need to navigate around. If there is Co, Ti or Ni there, that may make things more
complex. And obviously I will get nowhere if I choose a steel with no vanadium at all. |
I just did an experiment, and the results surprised me. I'd always thought that dissolving iron in HCl would always give iron III chloride, because I
thought that iron II would react with HCl. But apparently, in the absence of oxygen, it does not. I had a bright yellow/orange solution of iron iii
chloride and HCl bubbling away with some screws and various other bits of steel when I went to bed, and when I woke up, the solution was nearly
colorless, with just a tint of blue. Assuming you're trying to extract transition metals that have colored chloride salts in their lower oxidation
states, and assuming that iron will dissolve before the others, you could dissolve your steel in HCl, then keep removing the iron ii chloride as it
forms, until there's only the non-ferrous metals left. You'd be able to tell when this occurs, when the solution starts taking on a color that isn't
characteristic of iron salts. Peroxide will speed up the reaction, of course, but then you'd have iron iii salts until the peroxide got used up, and
the iron metal started to reduce them. Failing that, V2O5 is pretty cheap on eBay.
I'm going to try this with some spring steel and see what I get. Should be interesting.
[Edited on 2/5/17 by Melgar]
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JJay
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Spring steels are usually just plain carbon steel, possibly with some manganese. One exception is 301 stainless, which contains chromium and nickel.
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Melgar
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| Quote: Originally posted by JJay | | Spring steels are usually just plain carbon steel, possibly with some manganese. One exception is 301 stainless, which contains chromium and nickel.
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Yeah, it's definitely a stainless alloy; it's in these spiral rolls from a convenience store refrigerator that pushed bottles forward when someone
removed one. I chose this because it has a large surface area relative to its mass. I added it to a mixture of HCl and water, then added a small
amount of H2O2. It immediately started dissolving faster and the solution turned yellow, with some green collecting at the bottom. I imagine this is
nickel. It plated back onto the steel over time, leaving a dark discoloration. The solution gradually turned light blue, indicative of iron II
chloride.
If you were to do this on a large scale, suspend the metal in a plastic basket or something inside your container, so that when crystals start
forming, they don't cover your metal, and the carbon should collect at the bottom too. Make sure that there's at least some metal at every level of
the bucket, because this is will reduce your iron III if it ever forms.
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JJay
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There's a video on Extractions & Ire on YouTube where someone (Tdep?) prepares dichromate from silverware.
I'm not sure offhand what the best way to purify the nickel would be... the industrial route with carbon monoxide is obviously not well suited for
amateurs.
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j_sum1
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Yep. That's quite a good series (even if the process is rough as guts.) It is the one I was talking about here: https://www.sciencemadness.org/whisper/viewthread.php?tid=71...
Based on that (with some refinements) as well as some other work I have done, I am happy about separating Fe, Cr and Ni.
But at this point I am thinking more about the V and Mo in some of the steels. I would love to know some typical compositions so that I start off in
the most productive fashion. That information has been somewhat tricky to track down thus far.
The driver bits are the ones that are most attractive to me initially since I don't think they contain much Cr and Ni. They are magnetic (so not
austenitic and so probably minimal Ni) and they are not stainless (so less than 12% Cr, but I think probably way less.) If, hypothetically, they were
a couple of % vanadium, that would be a really attractive project for me.
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JJay
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Wikipedia lists a few but really doesn't have a very extensive list. It is hard to find a good list of tool steels, per se, but knifemaking is a very
popular hobby, so it's pretty easy to find lists for knife steels. A wide range of steels, including some of the most exotic, are used to make knives,
so I'd expect to see tool steels, spring steels, stainless steels, etc. on knife steel charts.
There is a pretty good list at http://knifeinformer.com/knife-steel-composition-chart/
There's also a list at http://www.zknives.com/knives/steels/steelchart.php
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Melgar
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News doesn't seem good; it seems that in most tool steel alloys, other metals are added at less than 1% typically. I believe the ones with vanadium
are the 6XXX alloys: chromium-vanadium steel:
http://www.efunda.com/materials/alloys/alloy_steels/list_all...
Sure, it says a MINIUMUM of 0.15%, but I doubt it varies too wildly.
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j_sum1
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Beautiful Melgar. I have found advertised driver bits with those steel grades.
(The closest I had gotten earlier was the rather nondescript "chrome vanadium steel".)
For example, http://www.abbeypowertools.co.uk/screwdrivers/bits-and-bit-s... and http://www.banggood.com/JAKEMY-JM-6118-33in1-Screwdriver-Twe...
It is so much easier to search when you know what you are searching for.
Those four Cr-V alloys you listed are all quite similar and so I will use that as a guide. The proportions of alloying elements are not great but I
think if I can end up with a solution that shows the four oxidation states of V then I will be quite happy. It does not matter much about the
quantity.
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Melgar
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Hey, glad my mechanical engineering background came in useful again. I haven't had to reference AISI steel grades in years now, despite taking
multiple courses dedicated solely to the chemical and physical properties of steel. It really is a very popular material to make things out of,
despite its infamous lack of corrosion resistance.
My stainless steel dissolving in HCl is starting to take on a violet hue. It's chromium, judging by Wikipedia. The nickel-green from earlier isn't
really visible anymore, although the solution is a really dark blue/black color, which could be a mixture of violet and green, along with the pale
blue from the iron. It shouldn't be hard to separate the metals, considering there are only three of them, and they all exist in substantial
quantities. I did make the rather dumb assumption that iron would dissolve before the other metals though, I'm not sure why I assumed that, since
it's clearly not true. It's only true really for nickel, apparently, because that was what was happening to the nickel as it dissolved.
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clearly_not_atara
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Vanadium in steel is typically at very low quantities, <1%. By contrast titanium alloys typically contain about 4% vanadium; the "standard"
titanium alloy composition is 90:6:4 Ti:Al:V.
Titanium is pretty cool too it's no vanadium but it does some cool things when it's a halide.
[Edited on 8-2-2017 by clearly_not_atara]
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j_sum1
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That's an interesting idea cna. I have some Ti coarse powder and I know it is not pure. Last time I played with it I got some yellow side product
that I assumed was Mo compounds. But it is possible that there is some V in there. (I will have to look up my notes to see why I concluded that
there was little to no vanadium. I don't remember.)
In terms of this project however, I don't have easy access to titanium alloys. I do have a bunch of reject tools cluttering up the place. So,
working with what I have might be some fun. And I am not so much concerned with quantities as the process. I am not really looking at recovering any
reagents here.
I have to confess that this project is mostly theoretical at the moment. My lab is not operational yet. (Seems to be taking a long time.) I am
mostly throwing around ideas and keeping the interest alive (and keeping sane in the process.)
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JJay
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I recently dissolved a bunch of kitchen utensils in hydrochloric acid. This piece, from a mixer, had rod that ran through it originally. The rod
dissolved, as did the weld on one end, but the stir blades and the rivet that holds them together appear to be almost impervious to the acid. I wonder
what is in them.
![IMG_20170501_145120[1].jpg - 451kB](http://www.sciencemadness.org/talk/files.php?pid=482082&aid=58895)
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Melgar
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It could just be a different grade of steel. If the two pieces were linked electrically, which they obviously were, the acid will dissolve whichever
metal is easier to dissolve first, then start in on the next when it's done with that. It's why galvanized steel tends to resist rusting, even in
parts where the zinc coating has worn off. Hydrochloric acid will dissolve stainless steel eventually, although it helps to put it in a sealed
container to prevent the iron ions from shuttling oxygen from the surface to the passivating chromium layer.
[Edited on 5/2/17 by Melgar]
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JJay
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I was thinking the same thing, but now I think it might be chrome plated.
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Phosphor-ing
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Sockets will likely be made out of chrome-moly steel. Unless they are impact rated.
https://en.m.wikipedia.org/wiki/41xx_steel
Which one exactly, will be anyone's guess.
"The nine most terrifying words in the English language are: 'I'm from the government and I'm here to help.'" -Ronald Reagan
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Melgar
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Hydrochloric acid should still be able to dissolve the chrome plating away, given enough time (at least a few weeks) and anoxic conditions. If you're
not patient, heating it would obviously decrease that time substantially.
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JJay
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Heating it really does decrease that time substantially, from weeks to hours for silverware in muriatic acid. I'm going to just throw that piece in my
next batch of dissolving silverware, and this time I'm going to do it in proper glassware so I don't have to blow on a 5-gallon bucket with a space
heater for days.
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