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unky_gumbi

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Aug 28, 2009
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So I am working on a full tang bowie and it was recommended that I harden the guard and pommel the thing is I don't do my own HT. I could fire up my little coffee can forge and go at them with that, but I know for a fact that it doesn't reach the temps I would need to get to full hardness. I think I am getting to about 1,400 maybe 1200 in these temps up here. I was able to melt salt once but it was a warm day.

Is this hot enough to toughen up the steel, or do I just send the guard and pommel out for proper HT with the rest of the knife? I don't really want to bother Rob with a couple of small parts if I can do it myself. The guard is O-1 and the pommel is 5160, I screwed up the 5160 guard and O-1 was the only steel I had that was thick enough and big enough for my design.
 
Hengelo 77,
Hardened steel will take a different color upon etching and bluing than soft steel. There is also a bit more rust resistance.

unkyG,
1200 won't harden steel. You have to get it above 1400. If your oven is getting to 1400F, then it will harden. Hold at that temp for 10 minutes and quench in oil. I would give it a try and see what happens.
 
Guess it wont hurt to try it at home first, I just looked at the weather forecast and it is suppose to be high of 29 today and 34 tomorrow so that is as warm as its going to get any time soon around here:o

Hengelo 77
The reasoning I was given was that the steel will also be a bit more scratch and ding resistant too. I know that the knife will see some hard outdoor use I want it to look good as long as possible.
 
you can harden the guard but make sure it is softer than the blade... if your knife gets flexed a hardened guard can become a knifebreaker (though you can also make your ricasso super strong to compensate

for the same reason the smiths use soft jaws in the vise for flex tests
 
wnease said:
you can harden the guard but make sure it is softer than the blade... if your knife gets flexed a hardened guard can become a knifebreaker (though you can also make your ricasso super strong to compensate

for the same reason the smiths use soft jaws in the vise for flex tests
Click to expand...

Yes I definitely wanted to draw back the hardness quite a bit, I would be looking for toughness over hardness in this application
 
unkyG,
A trick to get a bit more from a small forge is to wrap a second blanket of kaowool around the outside. Keep everything neat and in place with duct tape and aluminum foil. This layer does not need and coatings, as it is purely insulation. This works for most any forge or oven.
 
bladsmth said:
unkyG,
1200 won't harden steel. You have to get it above 1400. If your oven is getting to 1400F, then it will harden. Hold at that temp for 10 minutes and quench in oil. I would give it a try and see what happens.
Click to expand...

I aplogise Bladsmith, not to be snarky, and please correct me if I'm wrong but... since when wont carbon steel harden at 1200ºF ?:confused: Sure it won't be optimal hardening? But it isn't a blade either, it's a guard. So some (a lot) of RA will be fine since the whole reason he's doing it is just to achieve a color difference in etch. but it will harden to some extent, even if it's just a case hardening. which I believe would be optimal for his use...

Jason
 
Steel has a critical temperature of about 1400F.
At 1200F you would be doing a sub-critical annealling....and make the steel softer, not harder.

To expand on that, the steel will stay in the pearlite structure until it crosses critical.At that point it will convert to austenite, and with a quench the austenite can convert to martensite ( and possibly some RA). If it never crosses 1400F it will never be austenite...and there will be no RA....or any martensite,either.
 
I love the explanations, every time I read one of your little helpful insights I learn more than if I read a complete text book on the subject:thumbup:

I will be giving it a go tomorrow after my shift. I am guessing that I should temper it at work too instead of walking home and waiting for the oven to come up to temp and settle. Or can I get away with a quick temper cycle at work and. Do another when I get home?
 
For the purpose of this job, it probably won't make any difference. To be on the safe side, give it a temper at 400 at work, and then again at 450 when you get home.

Since it isn't a stainless steel, this won't apply, but up where you are ,you could just set it out on the porch after a snap temper it and do cryo in the ambient air.:D
 
bladsmth said:
For the purpose of this job, it probably won't make any difference. To be on the safe side, give it a temper at 400 at work, and then again at 450 when you get home.

Since it isn't a stainless steel, this won't apply, but up where you are ,you could just set it out on the porch after a snap temper it and do cryo in the ambient air.:D
Click to expand...

Well I don't think I have to worry about a cryo in the ambient air today


I should be fun freaking out the guys at work when I fire up my little forge on my bench, maybe I will get luck and get a bit of flame when I quench, that should get them running for the fire extinguisher:D

So just to make sure I have this right, I bring the forge up to temp put my pieces in, take them to non magnetic, let them soak for X minutes quench, and give a quick temper. I will be using canola oil to quench, should I clean that off before tempering, or is just a quick wipe to remove any excess?

Here's hoping everything goes well and I don't hear the dreaded snap, because if I do the whole project gets put on hold for a week or so till I get some more steel in to make another guard. You would think it should be easy to make a slotted guard, but it took me 4 tries to get it right:o
 

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Slotted guards are more difficult than they may appear.

I could be wrong but shouldn't you put the pieces in the forge as it heats up? Why wait for the forge to heat and then stick cold metal in it? I think that just uses up more time and fuel.
 
unky_gumbi said:
...<snip>
I should be fun freaking out the guys at work when I fire up my little forge on my bench, maybe I will get luck and get a bit of flame when I quench, that should get them running for the fire extinguisher:D...<snip[/I>]
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Man, do you own your shop?! The bike shops I managed, the landlords freaked out even when I would fire up the torch for brazing new frame tubes in, let alone a forge!

I work in construcrtion now so it's really no big deal when I do stuff like this, but it must be nice to play with this stuff while at work!


Good luck on your project, post up pics after you get it done.



-Xander
 
It is usually a better idea to place the metal in the pre-heated oven/forge. It is possible to greatly overheat the metal while the forge is coming up to heat. The flame may be directly on the blade and heating it much faster and higher than the insulating lining is heated.
 
fast14riot said:
Man, do you own your shop?! The bike shops I managed, the landlords freaked out even when I would fire up the torch for brazing new frame tubes in, let alone a forge!

I work in construcrtion now so it's really no big deal when I do stuff like this, but it must be nice to play with this stuff while at work!


Good luck on your project, post up pics after you get it done.



-Xander
Click to expand...

No I don't own the shop but the owner is pretty cool about things like this, he was the only one that stuck around to watch me get thing up and running. It is just a dual propane torch coffee can forge, not that big. It still makes a bang when I light the second torch:D

bladsmth said:
It is usually a better idea to place the metal in the pre-heated oven/forge. It is possible to greatly overheat the metal while the forge is coming up to heat. The flame may be directly on the blade and heating it much faster and higher than the insulating lining is heated.
Click to expand...

I did some reading and decided that it was better to let it come almost up to temp before putting the pieces in. They weren't that big and consistent thickness, so no edge to worry about. Still its better to set good habbits now rather than when I am trying to figure out whats going wrong with the HT on a blade:eek:

I brought the pieces up to non magnetic, let them soak there for a bit and quenched in the canola oil. Wiped them off and gave them the file test, which they passed:thumbup: I am doing the flash temper right now and once the forge reaches a safe temp I am heading home to do the second temper.

Thanks for the help bladsmth and everyone

George
 
JasonSCarter said:
I aplogise Bladsmith, not to be snarky, and please correct me if I'm wrong but... since when wont carbon steel harden at 1200ºF ?:confused: Sure it won't be optimal hardening? But it isn't a blade either, it's a guard. So some (a lot) of RA will be fine since the whole reason he's doing it is just to achieve a color difference in etch. but it will harden to some extent, even if it's just a case hardening. which I believe would be optimal for his use...

Jason
Click to expand...

RA can only occur if you get into the austenitization range. There won't be RA because 1200 is not in that range.
 
Thanks Acrid! been a while since I saw you over here. I respect both you and Stacy's answers. Thank you very much for them. So there can never be any sub critical hardening with heat?

Jason
 
There are a lot of factors to consider when saying "never", but at the end of the day, if your steel doesn't reach austenitizing temperature, then it won't create any new austenite to retain. If you're getting that high in temp, you are also very likely reducing any RA that might exist in a part. 1200F is right in the middle of the stress relieving range for annealed O1.

Consider also that with alloys like O1, things tend to happen slower than with dead simple steels. As I recall, Verhoeven calls this "solute drag". While things may be happening at sub-critical temps, they are happening at nowhere near the speed as critical (think of the time involved in spheroidizing at sub-critical), which isn't particularly fast with many alloys.

I'm not metallurgist and I don't remember the last time I stayed at a Holliday Inn, but there's what I understand of it.
 
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