cpm3v versus infi

fishface5 said:
Teh maker who goes by "Longrifle" on BF also makes knives in 3V, he might have some thoughts
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Correct. Matt would be an excellent source of information as well and is very approachable as most here are:thumbup:.
 
There's nothing magic about heat treating 3V, but it does require a fast quench to get it to the martensite formation point (~1000F). I think the problems people have had is just that. The alloying elements will snap up too much of the Carbon if the quench is too slow, and since there is only 0.8% carbon to start with you can't allow that. You lose some carbon to the alloying elements anyway, but you don't want too much and you'd like to retain free Chromium to provide some corrosion resistance. Done right, you should be able to achieve Rc61. AND, it will still be a very tough steel at that hardness.

From what I know, this is how it's hardened. BTW, Paul Bos is very open with how he heat treats steel, so there really are no secrets or magic. I use Paul for heat treating all my steels. IMHO he's the best there is for high alloys steels.

Austenitize at 1975F for 15 minutes.

Quench with forced air (I think Paul uses a cold nitrogen quench), quench plates, salt bath or oil.

Snap temper for 1 hour at 375F. This is a stress relief step before cryo.

Cryogenic quench overnight.

Double temper at 950F for two hours each.

What you end up with using this steel is essentially something very much like 5160 with about 8% Carbides added. I usually etch the steel for about 10 minutes in ferric chloride to passivate it and remove any surface oxide contaminants. It helps with the corrosion resistance issues which are mostly caused by those oxides. When this steel rusts it's usually in small spots with pits underneath the spots. You also get a pleasing gray patina that is useful in the tactical knives I make. A light coat any good synthetic gun oil will usually keep the steel rust free almost forever.

I wish I could help with the exact concentration of the FeCl I use, but after years of alternatingly adding water when it evaporates and fresh FeCl when it gets too weak, I have no clue as to what concentration is in my pot.

Hope that helps with the magic. :)
 
thanks jerry....been reading your stuff on the other forum...very helpful, and btw amazing work, your hollow grinds on thin stock are masterful
 
oh and also... i have a lot of o-1 heat treated by a reputable heat treater here in ontario, and at rc60 my thin edges suffer ductile failure during high speed strikes on mild steel. i mention this becasue i saw the pics you posted of an o1 blade chipping on steel pipe. if i'd known i would have taken t up at least another point, though o1 doesn't meet my needs for dimensional stability during heat treat.
 
Someone else posted that pic of an O1 blade. As you saw in that thread a 3V blade chopped halfway through that thick walled steel pipe with little damage to the edge. In fact he was able to sharpen it out.

If you got plastic deformation with O1 at Rc60, I have to think that it wasn't Rc60. Did you measure the hardness yourself? It might have gotten hot and had the temper drawn down a little. That's not normally how O1 fails. In fact a number of makers are using it in the Professional Cutting competitions and it's held up very well. Good steel.
 
wnease said:
has anyone tried S7 versus infi?
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Yep! When cutting bushes and brambles, INFI holds a better edge. When chopping an old bedframe to use up time which might otherwise be used productively, an overly thick S7 edge won't dent as badly as an INFI edge significantly thinned out by the end-user.
 
sodak said:
I've had great results with both. I've only gotten INFI from Busse knives (obviously), and have only used 3V with Fehrman knives. I think 3V holds it's edge longer for cutting, I haven't yet been able to test the 2 for chopping. Using DMT diamond hones and ceramic stones, they are both easy to sharpen to me.
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This is where I have had better results with 3V, in slicing. I have found 3v on my Hossom to hold an edge very well while slicing while my Busse's INFI holds it better while chopping. These arent scientific findings just things I have noticed while using my medium to large choppers. I really havent had much difficulty sharpening either however I think INFI takes less time for me to sharpen and strops up nicely.

Oh the maker "longrifle" is Matthew Roberts.
 
Not entirely relevant, but I recently bought some CPM3V from Matt aka Longrifle and he was great to deal with. I haven't even cut any of it yet, since I'm still learning about HT on simpler steels; it just seemed like a good deal and something to have on hand for when I learn to deal with other alloys and step up a bit.

My other thought is, it's difficult to really "compare" steels, unless you have blades made to the same dimensional specs. Tons of anecdotal evidence suggests strongly that 3V, INFI, and S7 are all very tough, high-performance steels, and I suspect they all can be made into a damn fine blade. On the other hand, an obtuse edge made of "super-steel" is not likely to out-cut a well-designed cutter made from, say, 1084. Lots of cutting comps are won, and ABS journeyman tests are passed, using the most simplest cutlery allows around. Geometry comes first. I'm just sayin'.
 
sure, James, geometry does the cutting, but abrasion resistance combined with edge stiffness keeps it cutting

i'm just looking for the best possible alloy for my customers
 
featherstone45 said:
+1....... My Fehrman blades have held there edges longer then INFI but you really have to be paying attention. Both are amazing steels, cant go wrong with either.

I just chopped out an entire pepper tree with my Fehrman FJ, Probably 4 hrs of chopping, still could shave after:thumbup:
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I got the opposite response, but really the difference was pretty small.

And I agree that four hours of chopping didn't dull my Fehrmans and don't dull my Busses. Well, if I avoid ironwood trees.:)
 
Fair enough, and well-said, wnease. As I said, I'm only beginning to work my up to the high-end steels. I applaud your desire to make the very best you can.
 
James, I'd use 1084 for my own blades but boy there are people on the other side of my table that think they need some super-steel (though they rarely if ever use my blades). Last show I had a guy want a sword over RC60, and most still want unbreakable. Oh and there is the issue of not being able to buy steel here. If I have to pay major shipping and brokerage fees I don't mind paying extra for a more marketable steel.
 
Since I acquired INFI, the vs thing is mute.
Thanks for an interesting thread.
 
Lycosa, makers hear that sometimes, but not everyone wants a Busse (really). I would order a run of a8mod with the extra nickel and cobalt if i could afford it and had access to Busse's heat treatment AND I thought it were really better. Everybody would. Everybody wants what's best, right?

Hey everyone...what if we make a group buy of a powder version of the INFI composition and then harden it the extra 4 rc points it will be capable of? Anyone have friends at crucible?
 
Thanks for the correction, Mark. Please don't tell my English teacher wife about my flub. :o
And, I realize that not everyone wants a Busse. Why, I don't know?? :D Some steels are soo close "perfect," why even compare them?
Thanks.
 
Lycosa said:
Some steels are soo close "perfect," why even compare them?
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Maybe because the steels which are great in some applications are less than great in others.

My most used knives on the cutting board use Aogami Super and everything else bugs me unless bones need to be cut. Aogami Super; at least used near full hardness as in kitchen cutlery; would be a huge mistake outdoors. The steel in my mower blade doesn't care that I live in rocky soil or that I 'sharpen' it with a carbide scraper, but it'd make for a worse than lousy chef knife steel even if I was using it to cut lemongrass.

I remember that link, Jerry! Another Jerry brought it to my attention. Not the one here; the guy who lights thermit charges to make his own steel.
 
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