Simple question: Is INFI worth it? Simple answer: YES.
INFI is the perfect fodder for forum fights—it is expensive, exclusive, and somewhat shrouded in mystery. It also has an air of impossibility towards it. All of this makes for partisanship and partisanship is the core of the dregs of forum participation. People against INFI decry it as a cheap industrial chopping steel that sells because of hype not performance. People for INFI speak of it in hushed tones, like the secret mantra of a long-hidden religious order. In the end, like with all things, I am not a partisan. I think both sides get it wrong. But the steel, well, the steel itself is pretty darn good.
First, I have no idea how it would perform outside the role in which I used it—as a steel for a big chopper. Second, because of a very generous friend, I was able to do whatever I wanted with the steel. His words—if you break it, I didn’t want it anyway. Third, I got to test it a lot, doing all sorts of fun things—chopping wood, building a small lean to, fire prep, and even some food prep.
INFI is a proprietary steel/heat treat and is exclusively produced by Busse. Apparently there have been at least two iterations of INFI with the later version using Nitrogen as a hardening element in conjuction with a reduced amount of carbon. Here is the steel composition chart. There is no datasheet as it is not a product of a metallurgy company (or, alternatively, this information is not publicly available). Additionally, there is no price per cubic inch because INFI is not commercially available in bar stock or rod form.
Hardness: 3 out of 5; just right for a chopper
INFI is generally hardened to 57-60 HRc and my sample performed as if it were hardened to this level. It was very sharp for a good bit of time, but less than something like S35VN or 3V. It didn’t do so hot in extremely coarse material like cardboard and rope, but nothing does well there, except for crazy stuff like Maxamet or REX 121. Its definitely not that hard, but I would be worried if it was, as choppers that hard will definitely chip (both of my most recent fixed blades in S35VN and 3V have had some issues with chipping). In terms of hardness it is appreciably softer than 3V, but then again, 3V was designed to be tough and hard with no concern for corrosion resistance. INFI is a bit more balanced and to achieve that balance it tends to be softer. It would be interesting to see how INFI would perform on a knife with thin stock.
Toughness: 5 out of 5; amazing stuff
Oh man, this is one of two places where INFI just stunned me. It is absolutely as tough as Busse claims. In using it to make a shelter, it took a beating, twisting and slamming into some rough and tough wood and occasionally hitting the ground on a overstrike or two. After work that chipped lesser steels, the INFI blade had only one small ding and I was able to get rid of it with a few seconds on a sharpener. The question is whether it is tougher than 3V. My answer is a qualified one. I have used 3V a lot. My go to fixed blade is a Bark River Bravo 1 LT in 3V and it has a lot of use on it. I feel very comfortable with 3V (and the the Bravo 1). I know what it can do. I still feel like I was exploring INFI’s capabilities. In that light I would say this—I have pushed 3V farther than I pushed INFI, but INFI never had issues with that I was doing to it. In fact it was less chippy than 3V even during my limited use. Is it tougher? It just might be, I don’t know. I just might have to buy a Street Boss and find out. Either way—you can’t go wrong. These two steels are the premium tough steels on the market.
Corrosion Resistance: 4 out of 5; if its not stainless, I couldn’t tell
I left sap and steak juice on the blade overnight and it had no negative effects. I have done the same to 3V and it looked awful and had to be buffed to get back to its satin shine. Compared to something more stainless, like D2, I still thought INFI was better. I have had D2 develop dull spots that looked like the precusor to actual rust, but again in my two or so months of use, INFI was no worse for wear. If its not truly stainless, its as close as it gets.
Sharpenability: 5 out of 5; the secret sauce of INFI is this—it sharpens like 1095 despite its high hardness and toughness.
If you sharpen your own knives you probably know the joys of 1095. It makes everyone feel like a grindmaster. It sharpens easily and the results are both aesthetically pleasing, a polished glow, and laser sharp. Unfortunately most steels aren't that good. INFI is. The results I got with my normal sharpening routine, which includes a Ken Onion Worksharp and some green compound, were, as its owner indicated when he got the knife back—screaming sharp. INFI is a joy to sharpen. And because of its high toughness, it retains that edge quite well and strops like a dream.
Overall Score: 17 out of 20 with a very high price premium.
INFI is one of my favorite steels available. As a chopper steel, I can’t think of a better choice. I do like it more than 3V in that role because it is nearly as tough, more stainless, and easier to sharpen. If toughness and hardness are your only concerns 3V is better and M4 is better, but for a balance INFI is darn good. The nitrogen does seem to make a difference as the low carbon content would suggest a buttersoft blade, but its actually quite hard, just a bit harder than good 1095 (like Rowen’s heat treated 1095 from ESEE).
Is it worth the money? Well, yes, from a certain point of view. If you want this combination of features in a steel, you have no alternative and so in that sense, it absolutely is worth it—its your only option. But if you can make some compromises, 3V does a good INFI impression. It is a different steel with different stated performance goals, but they are pretty similar.
I am a big fan of INFI, but beore I get rid of all of my 3V stuff (which I wouldn’t do—now that I have good sheath for my Bravo 1 LT, its hard to imagine using another mid-sized knife), I would like to see and use it on a thinner blade in a non-chopper role. It might be too soft for that, whereas knives like that in 3V are just awesome. A Bird and Trout knife or a 4.5 inch camp knife in INFI is my next fixed blade target.
Overall I really like INFI and the price premium, while very high, results in a steel that does stuff nothing else that I know of can.