01 - how much time do I have from quench to temper?

H

hammerface

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Mar 28, 2004
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I've been reading everything I can find on heat treating 01 as I am getting ready to attempt my first blade :eek: However, I am unclear on a couple little details and was wondering if anybody could help me out.

A) After I quench in the 130-140 F oil - how long to I have before I need to put in in the oven for tempering? (ie: Do I just let it cool to touch in the oil and then put it in the preheated oven immediatedly (smoke?)? or can I let it cool, clean it off, sand the scale off it, and then temper it?

B) Also - the only method I have of heating the blade is either a propane torch or possibly the large propane burner used for a turkey deep fryer. By using this method, would I be better off on focusing on just heat treating the cutting edge and edge quenching or trying to heat the full blade, tang and all, and then doing a full quench with the possiblitiy of doing a soft back draw afterwards?

I think I almost have it figured out (finally after reading and reading) - if anyone could shed some light on these last couple things I should be on my way. Thanks all! :D :D :D
 
O1 dosen't much like an edge quench, though it can be
well done with practice.

If you can get the entire edge above critical at the same time
with a torch, do it.

Quench into oil, preheated to 125 deg F. When the blade reaches the oil temp,
transfer to a oven, preheated to 400 Deg, F. Temper twice
at two hrs each.
 
A propane torch alone is not going to heat the blade hot enough. You're best bet is to get a Mapp gas torch kit from the hardware store. Mucher hotter. I get mine in the temper soon after quench. I quench, clean the blade then get it in the oven.
Scott
 
Clean the oil off the blade before you temper especially if you're using your wife's kitchen oven !!
 
Ok, this may be a stupid question but I can't seem to find the answer. What is a Mapp torch? I'm assuming it's the kind that takes the propane & O2 cylinder or no?.. Canadian tire has the one propane/O2 cutting torch set-up on sale for $57 CAN.
 
I used to use two small propane torches and was able to successfully get the edge to critical temperature. I'd put both torches on a bench, with the flames making about a 45 deg angle. Then I'd work the blade back and forth, starting at the ricasso, until the whole edge was up to critical. Not the best method, but it worked well for me for smaller blades.
 
hammerface said:
What is a Mapp torch? I'm assuming it's the kind that takes the propane & O2 cylinder or no?
Click to expand...

MAPP is an acetylene-like mixture (methyl acetylene/propadiene/propane) which burns at a temp in between propane and acetylene. Some "Bernzomatic-type torches are rated for MAPP or propane; others are rated only for propane. Here's some data from the Rio Grande catalog:

Acetylene/air: 4217F Acetylene/oxygen: 6000F

MAPP/air: 3600F MAPP/oxy: 5300F

Propane/air: 3497F Propane/oxy: 4780F
 
My oven takes quite a while to cool off so will it effect the heat treat if I temper the next day instead of immediately?
 
You definitely have something like 1hr to clean it up, wash the oil
off, remove anti-scaling compound, if you used any. Not sure about
a day. Steel is full of stress right after the quench and I wouldn't want
to test it, not after putting hours of my time into it.

Spend $20 and get yourself an electrical oven @ BestBuy (Euro-something). The internal chamber is something 16.5" wide, plenty
large for most knifes. It has 2 shelves, you can fit in a dozen blades easily.
 
Michael, it depends on the steel. I believe it's mostly about those stresses and cracking. Water-quenched 1095 can crack on the way to the kitchen oven immediately after quench, it's so sensitive. Fowler claims to leave 52100 in the freezer overnite between hardening cycles. I have left hardened ATS34 and 440C in the freezer for more than a week many times prior to tempering and I've never had one crack. Crucible often states that one can go directly from hardening quench into liquid nitrogen without a temper cycle with some of their stainless steels. I'd say the lower the alloy, the quicker it has to be tempered.
 
Michael,
If its 0-1 you will want to at least get it in a toaster oven for an hour at 350 degrees. From what I know 0-1 doent like to sit fully hardened :)
 
There is a lot of stress after forging and after hardening carbon steels. So the sooner the better as far as time before tempering. It's the same reason you would normalize immediatly after forging. All heat treating processes, normalizing, stress relief, annealing, spheroidizing, hardening or tempering are controlled by the addition or removal of heat over a specified time. For example, when tempering, if you raise the temperature you can lower the amount of time it is being tempered. The steel only knows that it has been held at a given temp. for a certain amount of time. It makes no difference to the steel if you temper at 400fh for one 6 hour period or three 2 hour periods. Putting a blade in the freezer only gives the ice cubes company.
Imho, Fred
 
Fred, I'd have to disagree with you on that thing about the ice cubes. They don't like company and do nothing but give the blade icy looks and the cold shoulder.... ;)

Actually, if one hardens stainless, then starts measuring Rockwell, you can actually see the hardness increase over the course of the next week or so of freezer time until it stabilizes. (Remove from freezer, allow to return to room temp, then measure HRC before returning to freezer.) It doesn't do that in the same time frame if just left on the bench. What I have never tested is whether the same blade will get harder yet if tossed into dry ice and eventually liquid nitrogen. Sounds like an interesting experiment.
 
O-1 is more tolerant than the 10XX steels.Clean it up and put in the oven within a couple of hours and you should be fine.The best practice is the sooner the better.Chilling a blade any amount below room temperature between temper cycles does some good,perhaps only a percent or two if the chill is in the freezer,but it will help convert the retained austenite to untempered martensite ( this is the same reason you temper at least two or three times,not one long time).Ed Fowler was freezing his overnight in the deep freeze between tempers with three tempers and two freezes.Dry ice is a better cryo,and LN is the best.Below the temp of LN there would be no more improvement for any steel we use for blades.
 
fitzo said:
Fred, I'd have to disagree with you on that thing about the ice cubes. They don't like company and do nothing but give the blade icy looks and the cold shoulder.... ;)

Actually, if one hardens stainless, then starts measuring Rockwell, you can actually see the hardness increase over the course of the next week or so of freezer time until it stabilizes. (Remove from freezer, allow to return to room temp, then measure HRC before returning to freezer.) It doesn't do that in the same time frame if just left on the bench. What I have never tested is whether the same blade will get harder yet if tossed into dry ice and eventually liquid nitrogen. Sounds like an interesting experiment.
Click to expand...
Ijust spent 15 min. answering your post and the damn thing crashed:mad::mad: Once more. I have little knowledge of stainless but I believe what you say;"It doesnt do it in the same time frame if just left on the bench" The time at temperature ratio at work. If you were to use an air hardening steel, hardened it, then put it in the freezer I believe it would harden faster than if you left it at room temp or if you went ahead and quenched it in oil. What I was trying to relate above was; If you harden a carbon blade, then temper it at a given temp for 2 hours, putting it in the freezer overnight does not affect it because you bring it back up to the same temp for another 2 hours. The steel only reacts to the fact it was held at said temp for 4 hours. Normalizing at 100fh above A3 then letting the piece air cool then doing the same thing again after it has cooled to room temp. Just repeats what you did before. If you lowered the temp to 50fh above A3 then let it air cool,that is different you would not have distroyed what you had accomplished but you would indeed affect the grain refinment process. If you repeat this {50fh] you would nullify what had just been accomplished. What do you think? Fred
 
It sounds good to me, Fred. I misunderstood what you were saying regarding the freezer.

How much chilling a blade affects it will depend on the specific martensite finish for that blade. With stainless, and I suspect most air-hardening steels, that temp is way below ambient. One thing I've never run across is data that actually graph the sub-ambient conversion of retained austenite versus time and temp. I have asked the question several times and never gotten a good answer: is it an absolute temp thing, or is it a rate phenomenon, such that a longer time at a higher temp achieves the same thing? This is getting into minutae of HT that are beyond my meager knowledge. If anyone has a source, I'd enjoy reading it.
 
I've had O1 blades kicking around for days before I put them in the oven. They were all stock removal pieces, and did fine. I find O1 is pretty forgiving.

You can increase the performance of your torch with a brick, just look up "brick forge". I suspect that is more effective than MAPP.
 
Please forgive but I took no time to read your thread or responces to it (numerous it seems) but rather instead respond shortly to your thread Heading.

How much time? There ain't no time. If you lag you loose, regardless of type high carbon steel (O1 or otherwise). To quench it goes - now. Practice like you can imitate lightening.

EDIT: At another and closer glance I see that you ask not about how quick to quench. My mistake and I apologise. The truth and again I read not the wise advise foretold above but rather offer my opinion (the truth - for sure) - TO TEMPER AFTER QUENCH (regardless of steel type for our purposes) is : hand warm. To say it better, allow the steel to cool uniformily to hand warm and immediately, upon that, place into pre-heated temper. Hand warm is were you can tolorate it within your closed hand without allowing it to cool much further before making your mind up. It is hand warm - that demarkation between untolerable and bearable. That is the immediate point at which the steel MUST be placed in pre-heated temper.

RL
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