Busse Carbon Content - 0.5% Carbon?

L

lupara

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Jul 30, 2002
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In the new issue of "Messer Magazin", the German periodical dedicated to knives, a metalurgic analysis of INFI has been made, which shows that - inter alia - the carbon content of INFI steel is 0.5%!

Although I do not have the magazine in front of me right now (i.e. I don't have the exact breakdown of the steel), there was no mention of "nitrogen" as an element of this steel compound, which is - as I hear - supposed to be what makes this steel so special.

Can anyone give me any degree of comfort that INFI is not just some hyped up, suped up version of 420?

Lupara
 
I am not so sure where you feel that Nitrogen is in INFI as much as it is a part of the manufacturing process INFI goes through. I am no metalurgist (In fact I probably speeled it wrong) but my understanding in my talks directly with Jerry is that Nitrogen is a part of the process and not necessarily a part of the steel. I can not say which part of the process as I am keeping my word to not divulge how it is made but it is science, just not rocket science.

INFI is awesome stuff, simple as that and it is NOT beefed up 420 unless Jerry was blowing nitrogen up my ass :D
 
Mike,
That was hilarious!

Lupara,
Welcome to the Forums!

INFI may only have .5% Carbon but it still is one of the, if not the best steel going out there right now. If you need solace, go to the Busse Forum and read the posts of all the ultra-happy Campers who have knives in this steel.
I have two knives from the Basic line which uses "modified" INFI, (supposedly not as great as INFI itself), and these knives ROCK! I kid you not, they cut and hack and chop with the best of them and keep coming back for more.
You really should try one of Busse's knives and see for yourself. I'm sure you'll be convinced it is the real deal after trying a knife made with INFI.

All the best,
Mike U.
 
lupara :

Can anyone give me any degree of comfort that INFI is not just some hyped up, suped up version of 420?
Click to expand...

Pretty much all steels can be changed to each other with a few shifts of the alloy content so in that respect you could call M2 a souped up version of 1084. However while not exactly false, it definately gives a misleading impression as the two steels are very different in character.

As for the carbon content, a high carbon content is needed to allow for the high carbide formation of the very high alloy tool steels. This gives them a very high wear resistance and is why they make such good cutting tools for abrasive materials, like hack saw blades need to be. The same does not carry directly to knives unless you are cutting similar materials with them.

The nitrogen in INFI is a carbide former, or more specifically a nitride former and thus allows a high wear resistance without the need for a high carbon content which can induce a loss in impact toughness and flexibility. It is why among other things that the Busse blades can withstand the high levels of impact and bending that they do.

Mike :

[nitrogen]

I can not say which part of the process
Click to expand...

It is the same way they get the caramilk in the caramilk bar.

-Cliff
 
Thanks guys - but maybe a further question would help me (once and for all ) clear this matter up for myself.

If I understand well from Cliff and Mike, nitrogen is NOT an element of INFI (i.e. a carbide), but it's somehow used (and that's the "caramilk" part!) as a "carbide former", which I take it means that it helps to "bind" the carbides in INFI in a way in which they could not be "bound" under a more "standard" manufacturing process, thereby making this steel very wear resistant whilst maintaining the flexibility and the elasticity of (as well as the ease of sharpening seen in) relatively low carbon steels.

My question is the following - is that last stament somehow in the ballpark or am I way out of town on this one?

Best,

Lupara

(P.S. Misque - I have a Basic 7 so I do know what you're talking about).
 
Originally posted by lupara
If I understand well from Cliff and Mike, nitrogen is NOT an element of INFI (i.e. a carbide), but it's somehow used (and that's the "caramilk" part!) as a "carbide former", which I take it means that it helps to "bind" the carbides in INFI in a way in which they could not be "bound" under a more "standard" manufacturing process, thereby making this steel very wear resistant whilst maintaining the flexibility and the elasticity of (as well as the ease of sharpening seen in) relatively low carbon steels.

My question is the following - is that last stament somehow in the ballpark or am I way out of town on this one?
Click to expand...

I think you got it right.
 
Nitrogen in steel forms nitrides by combining other elements that make up the steel, including molybdenum, tungsten, vanadium and even aluminum (aluminum is one of the strongest nitride formers).


Nitrides are similar to but separate from carbides (which are carbon combined with other elements of the steel). Both carbides and nitrides increase wear resistance, but nitrides are generally harder (and more effective) than carbides.


To answer your question, nitrogen is not used for forming carbides, but for forming nitrides, which consist of nitrogen combined with other elements.


There are basically 3 common ways that nitrogen is used in steels.


The first is mixed informally throughout the steel. For this the nitrogen must be introduced with the steel in a molten state, typically in an AOD furnace. This is how “nitrogen-strengthened austenenitic stainless steel” is made. The nitrogen-strengthened steels (as there name suggests), use nitrogen not so much for forming nitrides but for increasing strength.


The second is as form of casehardening (nitriding). Nitriding is essentially a surface treatment the combines nitrogen with the steel on the surface and a little under the surface, forming a hard nitrided case. Typically the nitrogen is introduced to the steel in a muffle furnace at 900-1000 degrees F (480-540 C), in the form of ammonia gas which dissociates into nitrogen and hydrogen. The free nitrogen readily reacts with the elements in the steel forming nitrides. The depth of case is dependant on the time spent in the furnace, for instance a depth of about 0.010” is obtainable after 18 hours, and a depth of about 0.030” after 90 hours.


The third is a coating (or surface treatment with little penetration below the surface). Buck for example uses zirconium nitride for their Ionfusion blades.


A disadvantage of both nitriding and coating, is that you need to use an edge that is sharpened on one side only, to keep the nitrides from being removed during sharpening.




-Frank
 
This is the chemical make-up of IFNI steel as confirmed by Jerry Busse.

V .36% Vanadium
Cr 8.25% Chrome
Fe 87.79% Iron
Co .95% Cobalt
Ni .74% Nickel
Mo 1.3% Molybdenum
C .5% carbon
N .11% Nitrogen

As you can see, there is .11% Nitrogen in the steel. Radioactive isotope spectral analysis can not detect Nitrogen and this may be the reason that it did not show up in this test. The problem is that this type of testing can not detect carbon either, so maybe a different type of testing was used.

.5% carbon is enough to make a very good knife steel. Combining it with the other elements in INFI is probably what makes this such a great steel. Then of course, you have the proprietary heat treat. It is the combination of all these factors that make INFI the excellent knife steel it is.
 
Thanks a million guys - makes alot more sense now, and I do feel better about my Busse.

Although the Basic 6 won a "camp knife" contest in the last issue of Messer Magazin, one may want to drop a line to these guys and tell them that their analysis of INFI was not complete, as it obviously failed to take into account the above. Here's the e-mail address of the person to whom this e-mail should be sent to:

h.wieland@messermagazin.de

It would make sense to do this because INFI doesn't come off too good in the article. I can do it myself, but I think that someone with the metalurgical know how to explain this thoroughly would be better positioned to write to these guys.

Best,

Lupara
 
Sooooo........? I am following along on this and have pretty much grasped what is going on here. Thanks for the explanation, Frank. Am I correct in assuming that Busse uses Nitrogen mixed into the steel as opposed to simply being nitrided? I know that Busse uses a very lengthy heat treating process, could this be a nitriding process? I am just a little curious.
 
Unless Jerry Busse is willing to "fess up", we just won't know. Personally I think it's more likely nitrides are melted into INFI. The chemical composition of INFI does not match any other commerically available steel, suggesting this is a special melt which wouldn't be beyond something like adding nitride briquets.

The surface casing of the steel with nitrogen is not practical with knives in my uninformed opinon. It would have to be done one knife at a time with an Ohmic heating process under a pressurized N2 atomosphere. This is expensive in the extreme, and the very shallow nitrogen penetration probably wouldn't do that much good for a cutting tool. Furthermore Jerry Busse stated his nitrogen content is 11%, that's way too high for sub-millimeter nitrogen penetration the Ohmic process could provide.
 
Jamie,

My GUESS is that Infi is nitrided.




Originally posted by tallwingedgoat
The surface casing of the steel with nitrogen is not practical with knives in my uninformed opinon. It would have to be done one knife at a time with an Ohmic heating process under a pressurized N2 atomosphere. This is expensive in the extreme, and the very shallow nitrogen penetration probably wouldn't do that much good for a cutting tool. Furthermore Jerry Busse stated his nitrogen content is 11%, that's way too high for sub-millimeter nitrogen penetration the Ohmic process could provide.
Click to expand...



Nitriding has nothing to do with an ohmic process and N2 (the inert form of nitrogen as found in air). It works by the dissociation of ammonia into hydrogen and highly reactive free nitrogen. The free nitrogen diffuses into, and reacts with the steel, forming a case.


Nitriding has been widely used in industry for many years. The major disadvantages of using nitriding on knives, I would imagine, are cost and the fact that you need to use some type of edge which is sharpened on one side only to prevent removing the nitrided case when sharpening.


BTW, I think that the nitrogen is 0.11% not 11%.



-Frank
 
Hmmm guess I miss read the nitrogen content. The only type of nitrogen steel I'm aware of not involving melted in nitrides are Ultra High Strength Steels and a Japanese process of using Ohmic heating under pressurized nitrogen. The process produce stainless steels with over 1% nitrogen. It's a rather specialized process and I thought it unlikely to be used for knife making.
 
tallwingedgoat,


I am not too familiar adding nitrogrn to steel with the Ohmic process, for some reason I was under the impression that the steel had to be heated to near the melting point for the pressurized N2 to combine with the steel. Thanks for mentioning it!



-Frank
 
This is all Chinese arithmatic to me. Nitro cellulose is good for making things be no more and certain fore extinguishers make beer cold. This and a hot girl named Robin who wouldn't give me the time of day is all I know about elements and the scientific stuff involving the elements.

Bottom line: The Busse knifes really do take a beating like no other and hold up very well for tough field usage. I really like them. I have and use other maker's knives, but the Busses are the ones to go with when abuse is anticipated.

Class dismissed.
 
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