440C heat treat/hardening advice needed

K

KILLAFORNIA

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Mar 4, 2006
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I'm sure that a similar question has been asked, but if any new members would like to chime in and greatfully any veteran members, I'd like to know their opinions on a heat treat process for 440C.

440C, it is what it is, and it gets high marks in this steel lovin' guys mind( yes, I;ve been drinking , but the question comes irreguardless.

O.K. the question... I've read that 440C can be air quenched )so to speak), well, what do you knifemakers think??? Is oil better, or can I get by with air?

Also (the real quesion)...and PLEASE let me Your thoughts on my plans, ..I actually want to get a good start at this y'know... o.k. here it is

If you've made it this far I commend you. cuz a post this long I'll normally just scan, so to speak, I promise to read posts more thoroughly for at least the end of the week. O!K!Heres my plan,


I want to heat my 440C blades at 1850F for a half hour (this is at my work, and our furnace hadsthe capability of having a non-oxygen atmosphere, meaning it is pressured by( I forget the specifics) Carbon Monoxide so I hope I can leave out wrapping them in foil, and I also can cool them down quickly with nitrogen, if necessary, and I have a oven that can range 0=1000degF no problem for tempering ( I read 300degF for a good RC[2 hours] 60-61.)
Havcing Olive oil or something might raise too many eyebrows so Air quench would be my best( But I don't know..is it o.k.?) Unless it better and I migjht be ablre to get away with it if it won't flare up.

Also.. I hope to get you knife makers expertise in the matter, I normally am more sober than now , so any responces by me will undoubtilly be more sober minded,

Thanks for any replys, and I hope your'e feeling as good as me right now!

---Killa(-just about to move outta-if this hippie sh!t keeps up)fornia

I'm 32....... so any of you gentleman who can relay some advice to this over grown teenager is MORE than appreciated... o.ok I think I've embarassed myself enough)


Damn Drunks:D

Thanx //// I think this post will make sense if read S-L-OW-L-Y.
Thanks gentleman
 
If you have the equipment use it ! Recommended hardening is 1850-1950 F. I would temper at 400 F for a bit more toughness...If you didn't have that furnace do it in foil and plate quench in the foil.
 
I just use the air quench and it works fine, the other advantage of air quench or plate quench is you get a chance to straighten in a vice while it cools.
 
Thanks, I was hoping it would work! I'll give it a try:thumbup: and more tougness sounds good too, I'll try 400F:thumbup:
 
No sane person oil quenches 440C. Air quench OK - plate quench in foil MUCH cleaner. Cryo has value - how much is an endless debate.

Don't ask too much of 440C. It doesn't perform well at RHC60. At RHC58, it is pretty tough and easy to sharpen - a good thing because you will have to sharpen often.

It's benefit is cost. For about $2 - $5 a blade you can get a MUCH superior blade steel. Consider the returns.

Rob!
 
Rob! said:
No sane person oil quenches 440C. Air quench OK - plate quench in foil MUCH cleaner.

Rob!
Click to expand...

Right on! Sounds like I'll be on track, and while I do have access to LNO at work, I was speaking/ thinking of using the nitrogen (to cool it faster)that we have running as "plant air", but come to think of it I might give the liquid nitrogen a try...
My whole idea for 440C was that I saw it could be air cooled, and wanted to make sure, because quenching some hot steel would bring too much attention to me, and also the furnace I have is regularly run at about 1850F...Its huge...and changing the temp. around can take awhile, and I don't want to get in the way of production times.

I know D2, is air-quenched, what other steels can be air/plate quenched?:D
 
mete would be a better person to provide the specifics, but it seems to me that a pressurized 100% carbon monoxide atmosphere would be just about as bad ( maybe worse) than an atmospheric chamber - as far as scale, oxidation, and decarb are concerned. ( after all, carbon monoxide is half oxygen). If the gas is inert or non oxidizing (argon, nitrogen,etc), it should be fine to use with an unwrapped blade.
It might be safer to go ahead and foil wrap the blade .

The air quench should be perfectly fine. A set of quench plates would be a good idea.
Stacy
 
Stacy you have to look at it the other way. Carbon monoxide is not the stable form but carbon dioxide is .So the CO wants to grab oxygen to become CO2. CO2 is neutral, CO is reducing.
 
Yes, I though of that, but it just seemed like at 1850F the weaker covalent bond might come apart and make it more reactive.But, you are right (as usual) that it would still be a reducing atmosphere. If I had thought a little more, I would remember that they wouldn't use it as a shield gas for some welding processes if it wasn't reducing.
Thanks for setting me straight.
Stacy

Even for some of us old chemists, the obvious isn't always obvious.
 
Perhaps the best match of steel for your limiting austenizing temp of 1850, would be D2. I understand the difference in stainless quality, but the difference in edge holding between 440C at 58 RC and D2 at 60-61 RC is very significant, as Rob pointed out. Many people don't cryo the D2, but cryo might be considered part of the heat treatment for 440C for best results. 440C for best stain resistance-D2 for edge holding.
Perhaps Mete could offer his thoughts about this.

Best wishes, Don
 
1850 F is on the low end of hardening for 440C and would minimize retained austenite.For D-2 hardening is from 1800-1875 F.I wonder what the capabilities of the furnace are for max temperature ? If you can get a bit higher your choice expands to the better 154CM etc.That would open up a big discussion !!
 
I can probably crank it up to 1950, the furnace will go higher but in that production environment the cooling down time, would be undesirable.

However, I had initially thought that 440C or D2, would be my only options as far as having a good Rc of 58-62 without having to quench in oil. After all I've read about quenching, I've thought it imperative.

I was also trying to keep it simple for the first couple knives, that I'm actually going to heat-treat.

I was also going to shape the blade, sort of "fighterish", where the attributes of good steel, IMO, are not as important, sharp pointy metal, still damages flesh as well as a "better" steel.

But I am very interested in what I can get away with with this furnace, because if all worked well, I'd like to try better steels for different knives...choppers, utility, camp/bushcraft, D2, A2, CPMS30V,

in fact I do have a blade in ATS34, that I was going to send out for heat treat, because of all I read of higher temps and quenching, you guys are getting my hopes up that I may be able to do this myself:D
 
CO is the active component of what happens in the reduction stack when I'm bloom smelting, the CO is very agressive about stripping the oxygen out of the FE2O3 so by the time it hits the slag pool at the bottom it's little bits of fe2

-Page
 
Thanks Mete. Yes going up to 1950 will provide a much better list of choices.

For a hard use chopper, do not forget about CPM 3V. At RC 60, 3V will offer great toughness and edge holding as well. I love the stuff! Do take care of it, it can pit, however.

Best wishes, Don
 
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