MattBower

Final update on the boric-acid-as-anti-scale idea: combined with a reducing atmosphere, it seems to have worked exceptionally well on the blade I mentioned above. I had sanded to 220 before heat treating. Afterward, although there were some variations in color on the surface of the steel, everything felt very smooth. I dropped back down to 100 grit to remove the discoloration, and that only took a few minutes. There was no sign of any pitting, no scale adhering to the blade, nothing, really. The biggest problem was some removing some glassy flux residue on parts of the tang that didn't get to hardening temps. Boiling water was the quick and easy answer to that. I'm definitely going to continue experimenting with this for simple carbon steel blades; I think it saved me quite a bit of sanding -- and I really hate sanding. This probably isn't the thing for high alloy blades that need hotter HT temps, because the boric apparently will become corrosive a little above 1600 F.

As a matter of fact, I have. Didn't have any problems with it. Got screaming hard in the quench (though knowing what I now know, I'd HT it differently). Sounds like you overheated yours. You can't treat high carbon like 1018.

Absolutely, Ken. That's one of the explicit reasons I do this. In having roughly 15 pieces of scrap analyzed so far, probably half have turned out not to be what the "conventional wisdom" says they "should be." Everything depends on the particular manufacturer's specs, what steel was cheap at the time, and probably a dozen other variables. Maybe some demolition bits are S-series steel, but the ones I have are 1040/45 -- and others are undoubtedly other sorts of steel. Not all torsion bars are 5160, not all files are 1.2%-1.3% carbon (or W2, or 1095, as the conventional wisdom often claims), and so on.

Me too! Maybe next time.

Morlock, I just visited your site and let me say that I'm very impressed with your work. Everything on your iron and steel page makes me say, "ooh, I wanna learn to do that." Thanks for the inspiration.

Not so different. They decompose into the same stuff at welding temperatures. If boric acid's what you have, use it. It's a common component in commercial forge welding fluxes, and Dr. Hrisoulas uses it in his "steel glue." No alcohol. Just sprinkle it on at a red/black heat; it melts fast.

Thanks, Jim.

Better not to even hear about that sort of thing.

Oh, those rangers! When I saw the title I thought you mean the U.S. Army kind. If you said Dunedain/Rangers of the North you could prevent some confusion. In any event, I'm sure either kind of ranger would be pleased to have this blade.

What Rich said. I think you'd be better-off starting with a known (or at least strongly suspected), medium carbon steel, preferably one piece. Of course pieces of decent steel that large and heavy can get a little expensive if you're not a good scrounger. But that's partly why the commercial pry bars you're looking at aren't cheap. I wasn't trying to give you a hard time with my questions; I honestly didn't know if you had answers to them or not.

I sent off another back of junkyard steel to my buddy with access to the mass spectrometer. Here are the results, some of which are very interesting: Torsion bar from jimbob, [added: off a Ford pickup]: C:0.60 | Mn:0.85 | P:0.030 | S:0.025 | Si:0.28 | Cu:0.01 | Cr:0.80 | Mo:0.02 | Ni:0.01 | Sn:0.01 | V:0.008 | Nb: - That's 5160. Cheapo, made-in-India, Harbor Freight bastard file: C:1.3 | Mn: 0.34 | P:0.015 | S:0.009 | Si:0.24 | Cu:0.01 | Cr:0.62 | Mo:0.005 | Ni:0.02 | Sn: 0.003 | V: - | Nb:0.010 Huge old, American-made mill bastard file [added: Nicholson]: C:1.28 | Mn:0.34 | P: 0.016 | S:0.015 | Si:0.15 | Cu: 0.02 | Cr:0.14 | Mo:0.005 | Ni: 0.02 | Sn: 0.002 | V: - | Nb: - Another huge old, American-made mill bastard file [added: Heller -- this may be a pretty old file]: C:1.20 | Mn:0.25 | P:0.010 | S:0.020 | Si:0.12 | Cu:0.04 | Cr:0.03 | Mo: 0.004 | Ni:0.03 | Sn:0.018 | V: 0.005 | Nb: - Note: when I get home tonight I'll post an update with the brands of the two American files; I can't recall now which was which, but one was a Nicholson. Did you notice that the steel in the cheapo HF file is extremely comparable to the old American files -- arguably even a little superior? Steel snobs, take note: just 'cuz it's cheap and made overseas doesn't necessarily mean it's crap. Railroad tie plate (surprise here for me; I was figuring on something like 1050): C:0.19 | Mn:0.42 | P:0.005 | S:0.030 | Si::0.04 | Cu:0.24 | Cr:0.05 | Mo:0.009 | Ni:0.07 | Sn:0.011 | V: - | Nb: - Used leaf spring of somewhat indeterminate provenance, from the dumpster behind my local truck spring shop (taken with the manager's permission!): C:0.57 | Mn:0.74 | P:0.010 | S:0.015 | Si:0.23 | Cu:0.25 | Cr:0.70 | Mo:0.02 | Ni:0.09 | Sn:0.008 | V:0.004 | Nb:0.070 Per the conventional wisdom about leaf springs, that's 5160. I was actually hoping for something else, just to help me once again make the point not to take the junkyard steel charts too seriously. But in this case the charts were right. The next one helps make my point, though. Big ol' truck coil spring taken from the same dumpster as the leaf spring, above: C:0.58 | Mn:0.82 | P:0.018 | S:0.016 | Si:0.90 | Cu:0.01 | Cr:0.46 | Mo:0.01 | Ni:0.005 | Sn:0.002 | V:0.094 | Nb:0.007 What's that alloy? A common junkyard steel chart says truck coil springs should be 5160. But this isn't quite 5160 (too little chromium), it's not quite 6150 (too much carbon and not enough silicon), and it's not quite 9260 (too much chromium, not enough silicon) -- and it has almost 0.10% vanadium, which is enough to make me think it might not be an accident. I'm really not sure what it is, to be honest. Should make a good, tough blade that hardens well even in a pretty slow oil, though. Here are the results for three pieces of mystery steel sent to me by Brian Brazeal. He can tell you what they came from, if he likes; I have no idea: Eye l: C:0.18 | Mn:0.60 | P:0.012 | S:0.029 | Si:0.015 | Cu: 0.53 | Cr:0.13 : Mo:0.014 | Ni:0.12 | Sn: 0.017 | V: - | Nb: - Eye ll: C: 0.58 | Mn:0.85 | P:0.010 | S:0.023 | Si:0.77 | Cu: 0.01 | Cr: 0.50 | Mo: 0.005 Ni:0.01 | Sn: - | V:0.004 | Nb:0.004 That one looks very similar to my mystery coil spring - not quite 6150, not quite 5160, etc. Eye lll: C:0.40 | Mn:0.86 | P:0.010 | S:0.034 | Si:0.30 | Cu:0.23 | Cr:0.88 | Mo:0.16 | Ni:0.08 | Sn:0.010 | V:0.003 | Nb:0.023 That's 4140.

What sort of steel is it that you're planning to use for the end? How do you know that it's hardenable, let alone that an oil quench is appropriate? What makes you think 400 is the appropriate tempering temperature? (That'd be in the ballpark for a knife blade, but if you're using high carbon steel it's liable to be too brittle for a pry bar. On the other hand, if you're using something marginally hardenable it might do.) Why do you want to heat treat before welding? Assuming you do it that way, what're you planning to do to keep the heat of the welding process from ruining the temper of the heat treated piece?

This guy is a collector, not a user. He's operating in a different world. And I gather $4-ish per pound isn't that high in the collector world.

Aftist got it right. Easiest way is probably to buy some Birchwood Casey Plum Brown, or another ready-made browning solution (yes, Brownell's is a great source, I'm a second generation customer), and follow the directions to the letter. You can also create instant rust many different ways. One way is by cold bluing a part (cold blue is available at most gun stores), then repeatedly dunking it in bleach and rinsing with hot water and a stiff plastic bristle brush between dunks. I've never tried that method for browning, though; I've only used it to get an antiqued/etched appearance. Experimentation on something expendable would be in order. I'll warn you right now that you'll be amazed at how aggressive the combination of cold blue and bleach is.

Yes, borax in water was another possibility. I liked the alcohol and boric acid idea because alcohol evaporates fast -- i.e., my "anti-scale" dries fast -- and I figured boric acid might bubble less than hydrous borax. I'd have to say that latter idea didn't really pan out, though.

A while back I sent off a piece of bed frame angle for analysis, along with some other scrap steels. Glenn saved the results to the junkyard steel blueprint. The bottom line is that it was 1055. Which isn't anything special by tool steel standards, but it should still get you RC 60.

By my way of thinking, any forge that needs 200 CFM is huge. I used to drive an enormous oil forge to a self-destructive, blinding white using probably not much more than 100. (I got rid of the oil forge because it was just too hard to control.)

Will do. It definitely formed a kind of glassy coating on the steel. I know because while most of it came off in the quench, parts of the tang that stayed fairly cool still have some glassy droplets sticking to them.

Trying to describe steel temperature by reference to color is notoriously inaccurate; one man's cherry red is another man's orange. Nevertheless, it's a heck of a lot more accurate than blindly cranking your regulator up to a pressure suggested by someone with a completely different setup and assuming that this is going to produce a desired temperature. It absolutely will not. If I gave you a number and the interior of your forge turned bright yellow (which could easily happen), would you just shrug and say, "I guess that must be cherry red?" I think the only way you can hope to achieve what you want is by building a forge, obtaining some accurate way of measuring the temperature inside that forge, using the forge a lot, and watching carefully how everything you do affects the temperature inside. You might get good use out of Tempilaq. Google it.

Grant, I heat treated a small blade today, using a slurry of boric acid and 90% isopropyl alcohol as an anti-scale compound. I painted on several coats. With gentle heat the stuff dries very quickly, and although the coating it was fairly fragile it adhered well. I got a little worried when I stuck it in the forge, because it immediately started bubbling. But it settled down as the steel started to heat, and it seems to have done a pretty good job. I'll get a better sense of things when I start sanding, but the steel looked really clean coming out of the quench. I also used a reducing atmosphere.

Try Rutland furnace cement from the hardware store. It's awfully sticky stuff. A lot of folks, including me, have had decent luck with it. If you want to use natural clays, try adding some grog -- stuff that won't absorb water, and so won't shrink as it dries -- to the mix. Clean play sand will work. Go at least 1:1 grog to clay. If that doesn't work, go to 2:1 or even higher. Pure clay shrinks a great deal as it dries, and that'll cause all kinds of problems.

Welcome to my world. Living in the shadow of DC, I've never yet found a scrap yard that'll sell to me as an individual. Even getting into the yard is a total no-go. As far as I can tell they generally forward the stuff up the chain to single buyers, which I assume either stick the scrap on rail cars and ship it to U.S. steel mills for remelting, or put it in containers and ship it to China for the same purpose. I can still go to an auto junkyard and buy parts at used part prices, but that doesn't usually work out to be a great deal. Of course it all makes perfect economic sense, but it still sucks.

Found it. http://www.iforgeiron.com/forum/f57/generating-voids-middle-13262/ Of course that's possible with a material that's sufficiently thermally conductive, especially if the heat source isn't extremely hot (O/A flame, electric arc, etc.). (For these purposes fast induction heating is like a really hot external heat source, because it acts almost entirely on the skin of the steel.) I just didn't realize steel was that thermally conductive.

Grant, I just learned about them; I plan to try boric acid and alcohol on a blade this weekend. The borax slurry was recommended by a metallurgist who used to supervise heat treatment of F/A-18 landing gears. He said he used a paint made of borax and solvent (he didn't say what solvent) on the gears during heat treating. Of course he also used a fancy protective atmosphere in the furnace, but that's not practical for most of us. The boric acid and alcohol idea came from an engineer who's into bladesmithing, and a goldsmith confirmed that it's a standard anti-scale dip in his profession. I'd post links, but I don't want to offend anyone. You can find the threads pretty easily with Google. I'm aware of the commercial compounds, but cheap and improvised are my middle names. :)

Lemme preface this by saying that you've heat treated one more anvil than I have, so all I'm going on here is what I think I know about metallurgy and heat treating. I think you need to let it soak at least a little to let that good austenitizing temperature penetrate into the steel. Not all the way through, I suppose, but I'd think preferably an inch or so. Otherwise you'll end up with a thin, hard skin over a relatively soft center. That'd be better than nothing, but not ideal. One possible, at least partial solution to your decarb problem might be to coat the anvil with an anti-scale compound. Boric acid (readily available as roach killer) dissolved in alcohol and painted on, then allowed to dry until the alcohol evaporates, will help. You can do the same thing with borax dissolved in hot water. But beware: as I understand it they both become corrosive to steel above 1600 F. Whether you need to normalize depends on what you've done to the steel up to that point. If you've been welding on it, you'll probably have some fairly large grain in the heat affected zone that could use a normalizing cycle (or better yet, two).