Infi.

H

Heart View

Joined
Sep 23, 2011
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Has it changed over the years? It may be my imagination, but it seems tougher now, with maybe a small reduction in edge retention.
 
"infi 2" is in the works right now, but as for original infi, I'm not sure. Jerry will probably chime in soon enough
 
I don't believe the base recipe has change. There may be some evolution to the heat treat process.

I also believe that Jerry backed off on the hardness over time, the web site currently says RC 58-60. I think the earlier blades where 59-61 (?), and when they introduce the Anorexic Active Duty (BAD) he ran the hardness up to 60-62 for the thinner blades.

The drop in hardness would account for the increased toughness, at the expense of edge retention.
 
There was another post to that effect a few months ago. We have no info on that from Jerry.

If you go way back, to the early SHBM, those were hardened to Rc 60. After that, Jerry backed it off to Rc 58. Since then, no changes as far as we know.
 
http://www.calce.umd.edu/TSFA/Hardness_ad_.htm
"1. WHAT IS HARDNESS?

The Metals Handbook defines hardness as "Resistance of metal to plastic deformation, usually by indentation. However, the term may also refer to stiffness or temper, or to resistance to scratching, abrasion, or cutting. It is the property of a metal, which gives it the ability to resist being permanently, deformed (bent, broken, or have its shape changed), when a load is applied. The greater the hardness of the metal, the greater resistance it has to deformation."

INFI 2.0 is not a different composition. It is a different heat treatment/temper process. The harder version will help decrease plastic deformation at thin cross sections. It will also help to reduce the ability of hard grit to cause microscopic deformations that lead to the imperceptable dulling of the edge. Tearing out a carbide is only one form of edge damage that leads to 'dullness', microscopic mashes, dents and rolls are others, all of which are reduced by increased hardness.
 
I believe they backed off the hardness a few points to ensure consistency, I'm guessing that earlier methods to produce harder INFI where not 100% reliable and some knives came out softer. Not a quality issues so much as an impediment in efficient production. The slightly lower Rockwell probably means that edge deformation occurs slightly sooner over long durations of use, you have to use the smooth steel/ceramic rod slightly more frequently. So that might be perceived as lower edge retention in the slightly softer INFI. Or at least that is the impression I have.
 
INFI is carbide lite to start, IIRC ~0.5% C, about half the carbon content of 1095, so the 'big'' carbides like you see in D2 aren't there, even though INFI has a comparable chromium content.

Much of the reason it's possible to get INFI so sharp, is small grain structure, my understanding is that nitrogen is compensating for the low carbon count. But then I'm a biker not a metallurgist :D so maybe one of our resident scientists could clarify.

Edge holding and "toughness" are fairly inverse to each other. Glass can be extremely sharp, but it's brittle and chips, mild steel is tough and malleable, but won't hold an edge worth a .....

INFI is the best trade off I've seen between the 2 extremes, you get a malleable edge which can take and hold an incredibly fine edge.



$0.02
 
resinguy said:
There was another post to that effect a few months ago. We have no info on that from Jerry.

If you go way back, to the early SHBM, those were hardened to Rc 60. After that, Jerry backed it off to Rc 58. Since then, no changes as far as we know.
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Agreed, my SHBM and SHSH2 both ring when struck, the newer stuff I have has more of a "thunk". I wonder if there is a hardness at which steel starts to ring rather than "thunk"? :confused:

Both perform equally so far, but I do prefer a deformed edge rather than a chip when hitting rocks and such. :o
 
So the general consensus from the users point of view is that the physical abilities of INFI have changed- most likely a lowered hardness. I would like Jerry to say his two cents. I am extremely excited for INFI 2.0, I wonder how that edge retention will be.
 
1966c10 said:
This is all really interesting stuff guys. If someone could chime in and clarify a few things though.

The lower Rockwell, I'm assuming, is due to adjustment in the tempering process. Tempering doesn't get rid of carbides that were formed. (correct?)

So assuming edge geometry is such that carbides aren't tearing out of the matrix, wear resistance is not significantly decreased by tempering the rockwell lower. But toughness and the potential for edge rolling are increased. (correct?)

I haven't noticed my (fairly recent manufacture) INFI knives rolling on materials like food or even hard wood like mesquite. So I don't get how any edge retention decrease is possible just because rockwell is lower on later Busse knives.
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Edge retention is more than wear resistance. If a knife is too hard, it loses edge by way of chipping (and has to reground). Too tough (read:soft) and the edge simply rolls away and disappears. Wear resistance helps when doing things such as cutting cardboard, however, for survival purposes, toughness is generally more desirable. The magic of INFI resides in its toughness, hardness, and edge 'rollability' as opposed to chipping.
 
Allcaps321 said:
I believe they backed off the hardness a few points to ensure consistency, I'm guessing that earlier methods to produce harder INFI where not 100% reliable and some knives came out softer. Not a quality issues so much as an impediment in efficient production. The slightly lower Rockwell probably means that edge deformation occurs slightly sooner over long durations of use, you have to use the smooth steel/ceramic rod slightly more frequently. So that might be perceived as lower edge retention in the slightly softer INFI. Or at least that is the impression I have.
Click to expand...

I have no reason to beleive that busses use of a lower rockwell was based on poor reliability of their heat treating process. More likely it was a choice made based on destructive testing of multiple rockwell hardnesses. As you say, the slightly softer INFI provides better protection against failure/breakage, while providing an easy to sharpen product.
 
Heart View said:
So the general consensus from the users point of view is that the physical abilities of INFI have changed- most likely a lowered hardness. I would like Jerry to say his two cents. I am extremely excited for INFI 2.0, I wonder how that edge retention will be.
Click to expand...

I haven't heard anyone say that the edge retention between the older 60-62rc SHBM's and the 58rc FBM's dropped notably. If it has the difference is negligible enough that it hasn't been a source of contention or wide discussion over the past 9 years.
 
INFI 2.0? Different heat treatments? Are they going to do smaller blades differently from larger ones?
 
Last Visible Canary said:
I have no reason to beleive that busses use of a lower rockwell was based on poor reliability of their heat treating process. More likely it was a choice made based on destructive testing of multiple rockwell hardnesses. As you say, the slightly softer INFI provides better protection against failure/breakage, while providing an easy to sharpen product.
Click to expand...

Well reading the thread "Always Experimenting With INFI..." Jerry posts lead me to believe that. http://www.bladeforums.com/forums/showthread.php/865983-Always-Experimenting-With-INFI-.-.-.-.
Jerry Busse said:
We have been experimenting with a new heat treating procedure for INFI that we have termed CNQ which promises to deliver a consistently higher hardness as well as, what we hope will be, a considerable increase in cutting performance on certain materials.
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Emphasis on consistently. Of course this isn't very much to make an inference on, it could be seen two ways, they plan on making INFI even harder then before, or they had difficulty producing the harder INFI of the past.
 
1966c10 said:
You're saying edge retention was better previously? Man, I need to get me some older stuff because my CABS and B11 retention is already killer for not being some 1000% vanadium PM steel. The edges are very plastic. They aren't hard to move out of alignment with lateral pressure on hard materials like cooked bone, but in turn, a ceramic rod puts it right back and it's still sharp as it hasn't worn down or chipped.
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And that is what makes it so great as a hard user steel! Triple handful of steels are better (some Way Way better) at edge retention for abrasion resistance. But smack a rock while chopping, or hit bone or glass or ceramic while cooking/food prep and you have some real work fixing the edge!

I sure do love the higher hardness in the BAD! great stuff, and I think I would like that level hardness in all my smaller Infi! (I am thinking my CABS and MUCK would be even better!).
 
Allcaps321 said:
Well reading the thread "Always Experimenting With INFI..." Jerry posts lead me to believe that. http://www.bladeforums.com/forums/showthread.php/865983-Always-Experimenting-With-INFI-.-.-.-.


Emphasis on consistently. Of course this isn't very much to make an inference on, it could be seen two ways, they plan on making INFI even harder then before, or they had difficulty producing the harder INFI of the past.
Click to expand...

I definitely see where that could be interpreted that way. Either he meant that INFI had a variable hardness when trying for 60-62 (so some might be 59 while others 62), or he just meant that all blades would be harder then they were before. One more interpretation is that garth mentioned the possibility of 64rc which is above what jerry said INFI could go. He's said when commenting on a 'thin and hard' thread that INFI just can't go above 62. If he was able to find a heat treat to get it to 64, he may have been referencing 'consistently harder then we've every been able to get INFI'. Or it could be again what you said where aiming for 64rc was a gamble before, with a portion coming down to 62.

I dunno :confused:
 
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