accidental "heat treat"?

W

wdmn

Joined
Nov 29, 2013
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167
Hi all,

Wondering about whether, in theory, by overheating steel and then quenching it (without the intent of re-tempering) you could serious mess with it's hardness?

I've been working on a of couple axe heads that were previously abused: sharpened with a grinder and then plunged into cold water, possibly repeatedly. The steel on them is very hard now, too hard to file. I know that if you mess with a temper it would make the steel softer, but could you potentially "heat treat" unintentionally (I know technically it's only a heat treat if you do it on purpose... but for the sake of this thread...)?



wdmn
 
Take some good sand paper to it. Or a diamond file. After taking off the thin outer layer see if your file skates.
 
No. That wouldn't be hot enough to harden steel. You need to take it up to the point where it becomes non-magnetic - around 1500-1600°F - depending on the steel.
 
Sh^te, I gotta find another explanation, it's makin me loopy. I just don't get it; I thought the keech casting method explained the first one, but now I got another that isn't even a racing axe... in between the two I reprofiled and sharpened three axes without problem. I sharpened close to 2 dozen axes in the last 8 months without problem... Why two so close together (and both from same owner)...? mystery.
 
Well, do you know who made the axes? Do you know the steel that was used? Do you know if the head was re-hardened? Some axes come with the bits or edges harder than average-some into the high 50s HRc. Custom ax heads might be made from a different steel-if a maker made a head from M2 for example it would temper from the low to mid 60s HRc. If someone was knowledgeable and wanted, it is a fairly simple matter to re harden an axe made from a simple steel (1075 for example). As quenched, such an ax would be in the low 60s HRc. You might post some pictures and let us know what you find out?
 
The good ones and many of the old ones are good are often too hard for what often passes as a file these days. Diamond stones are good for the hardest ones, while natural stones will work well enough for some. I read somewhere that makers reduced final hardness these days so that people could sharpen the axes with the crappy files generally available. Most likely you've found some good axes. Now you need to find some good files or other method of sharpening! At least it doesn't sound like you ruined the temper :)...
 
BG_Farmer said:
...... too hard for what often passes as a file these days.
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I think that's a common problem. And technique plays into this, too. If your axe isn't secured in a sturdy vise at about navel height then you're not in a good position to file an axe.



Proper%20filing%20position.jpg


Filing.jpg
 
Thanks guys.

The first head that I came up against was a keech racing axe. Figured the answer there was that keech has their special "keesteel" and special casting technique. That seemed to make sense.

The second one has been gone over with a grinder so any markings were gone. There is a remnant of a sticker showing what appears to be an "Indian" in headdress. The cheeks are very concave with no raise in the centre line.

These heads have been in the possession of people who don't really have any sense of what they're doing (even less than me), so I don't think the heads were intentionally hardened.

When I was first starting out I came up against a bunch of problems due to my technique and the files I was trying to use. I eventually bought a new grobet file with double cut on one side and single on the other. These files are supposed to be rated between 60-62 HRc. For these two axes I was using a pretty much brand new file. The keech actually broke a couple of teeth on the file. I'm under the impression that these are some decent files. I know that grobet also makes what they call the hardest files around (Grobet valitian at 72 HRc)... I saw some other swiss files at about 66-67 HRc http://www.fine-tools.com/feile2.htm, and then some machinists files at 70... but most of these are not the right size. Is there somewhere else I should be looking.. I avoided getting a Nicholson because I understand they're made in mexico now.

Thanks for the suggestions on adjusting my method; it's definitely not as good a set up as you've got going there Pegs (nice to see you at work!). My set up is a bit too low (around the top of my thighs), and I don't have a good vice. What I usually do (and did with these two heads) if the head is not on a handle is put a piece of wood through the eye and then clamp it on both sides to the work bench with c clamps. If there is any movement in the head I shove a wedge or two under the cheek.

Diamond stones have quite the price range... what should I be looking at if I go that route?
 
I don't think it's your files and it sounds like your clamping techniques are at least adequate if not ideal.


wdmn said:
The first head that I came up against was a keech racing axe. Figured the answer there was that keech has their special "keesteel" and special casting technique. That seemed to make sense.

The second one has been gone over with a grinder so any markings were gone. There is a remnant of a sticker showing what appears to be an "Indian" in headdress. The cheeks are very concave with no raise in the centre line.
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I'm thinking you might have just had the bad luck to come upon two oddball axes in a row. The Keesteel might well have been exceptionally hard. The second axe might be some new import made from recycled steel. Sometimes recycled steels aren't well homogenized. Could be part tin can, part car fender and part lawnmower blade or drive shaft (hard steels). In recycling you can save money if you don't heat the metals up enough for them to fully integrate or mix together. Then you might have a product made with vastly different steels right next to each other. If you then use a heat treating method designed for the mix you could end up with wide variations in hardness between one part of the axe and another. I've seen rebar made from recycled steel where you could easily see nuts and bolts that hadn't been fully melted incorporated into the mix.

Diamond stones have quite the price range... what should I be looking at if I go that route?
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Not an expert on diamond hones. But many of these knife guys are. I have a few. My experience is that I've never seen a diamond hone remove material as fast as a file - assuming the material is fileable. I've read that some of the new coarse diamond hones remove steel pretty quickly - like the best stones.
 
Nicholson files are still pretty darn good, even though they're made in Mexico. Way better than anything else you can get at Walmart, Sears, or Home Depot. I just recently got a new 10 inch bastard and it's pretty nice.
 
So how many MPG are you guys getting out of a file? What is the life expectancy? Have you ruined a good file on a hard axe?
 
Are you working towards show or towards go? If you are looking at a good working edge get several sheets of silicon carbide wet/dry sand paper in different grits. Glue it up to some flat sticks. You are making a poor mans belt grinder. It will take time but you can certainly profile and sharpen most any ax this way and it is a lot less costly than good diamond sharpeners. A file will give a smoother cut for the material removed in a short time, but you can polish to a mirror finish with the sandpaper over a longer time.
 
Thanks all for the helpful responses.

Yeah, I'm inclined to think you're right pegs; the second axe certainly did not strike me as being high quality. Not that I've got tons of high quality axes myself, but I've seen enough here on the forum to know. I've also noticed the difference in hardness between some of my axes. I have a double bit welland vale true temper that is a challenge to file (especially with the nice patina), but it is possible.

Bo T; this is all for go... I've heard of silicon carbide being stuck to a plane of glass, laid flat and treated like a stone, but I like the idea of trying it on some flat sticks and being able to take it to the axe in hand... seems like it would take an awful long time though.
 
wdmn said:
Thanks all for the helpful responses.

Yeah, I'm inclined to think you're right pegs; the second axe certainly did not strike me as being high quality. Not that I've got tons of high quality axes myself, but I've seen enough here on the forum to know. I've also noticed the difference in hardness between some of my axes. I have a double bit welland vale true temper that is a challenge to file (especially with the nice patina), but it is possible.

Bo T; this is all for go... I've heard of silicon carbide being stuck to a plane of glass, laid flat and treated like a stone, but I like the idea of trying it on some flat sticks and being able to take it to the axe in hand... seems like it would take an awful long time though.
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This is just for your problem axes. It will take longer but it is better than breaking teeth off the files. A file is still preferable, if you find one that works. Although, the sandpaper will work well for putting on the final edge. I always use sandpaper (and files) in a poll to edge direction.
 
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