INFI as a small blade steel? vs. others

I will agree with SR101 being my prefered choice in blade steel if you are staying in the Busse camp. While INFI is amazing, for what I do I just prefer SR101 (52100). I think far to many people look at SR101 as some how being inferior to INFI which in my eyes is a huge mistake. Now if I was going custom on a small knife something like ELAMX K390 or S110V would be my choice.

In the end I would also most likely go with CPM-3V over INFI for this reason. For any normal human uses 3V and INFI are tough to the point of not being able to tell a difference in the two but 3V with holds its edge a bit better (given equal geometry) and IFNI will be slightly more stain resistant.
 
james terrio said:
Not everyone uses small/thin knives just for slicing rope or sushi all day. Many (perhaps most) of us need to be able to whittle, carve, debur, scrape, etc. with a small, light, handy knife. That can put a lot of side-load on a blade - hence my comments about thin edges and chipping.
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But those don't involve impact. What I meant is that fracture measured by charpy or izod is not the same as fracture that comes from the side-loading you are talking about. There are also the issues of plasticity and yield strength. Getting a harder blade is usually better, since that mostly means a higher yield, so it takes more force to exceed the elastic limit. We can use a ton of steels as tough or much tougher than INFI, but if they are 5 to 10 points softer, they do little good. 9V would be a great choice for wear resistance and toughness if you could get a blade harder than about 55. It depends on if the fracture strength is the same as the tensile strength to make a metal brittle of not, but it isn't the hardness that is an issue. Until you exceed the elastic limit, the blade won't fracture. You need the right kind of steel, but also enough steel, to keep it together. Most high speed steel used to cut other metals doesn't have a chipping issue at 64 Rc, and it doesn't have anywhere near the impact toughness of INFI. HSS isn't used for jackhammer bits, though.
 
S5 would be a better blade choice, both higher hardness and higher toughness with similar wear resistance. But it just doesn't have the availability of S7.
 
PatrickKnight said:
I think far too many people look at SR101 as some how being inferior to INFI which in my eyes is a huge mistake.
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Not really. Back in the day when I used to hang out in one of the Bussekin forums (but not the BC forum), I ran a poll that asked which of the Bussekin alloys most people prefer by category. The only category INFI won easily was the chopper category. Everything else pretty much went to SR101 based on its price to performance ratio.
 
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hardheart said:
But those don't involve impact. What I meant is that fracture measured by charpy or izod is not the same as fracture that comes from the side-loading you are talking about.
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Regarding INFI and Jim's tests, it matched a 154CM blade at 61 Rc but is steps below the high-carbide powder steels at the same hardness. At different hardness, I am not sure that you are really comparing the steels anymore, unless one steel just can't reach the hardness of the other (as Hardheart elucidated).

But regarding side-loading and charpy/izod impacts, those impact values correlate to cross-sectional area, don't they? As the area is reduced (as on a blade edge), the impact force required for fracture is also reduced. Side loading can be static or dynamic, it can happen slowly (testing plasticity and UTS) or it can happen suddenly, thereby calling upon impact toughness. When a blade slips against a hard object, however gently, the sudden impact is indeed an impact. When cutting cardboard boxes or carpet, blades can impact against staples - it isn't chopping but it is still an impact. Impact toughness plays a role in small knives as well as large knives. Or did I miss something?
 
Infi does great in small blades, it still holds a better edge than any 1095 or 1084, it's corrosion resistant, and it can take a fairly thin edge without chipping becoming a concern. It's just that there are steels that tend to work better at that size range for most tasks, M2 at RC 64 is one of my favorites for smaller stuff, very stable at the edge and to date is the easiest steel to push the limits of my sharpening abilities on. (oh, and I've not seen an S30v blade more chip resistant than my old M2 AFCK) I haven't tried CPM M4 at 62+ yet, but I imagine I'd really like it.
 
hardheart, you're right to point out the important differences between gross impact and plasticity and yield strength. I do have a very basic understanding of the modulus of deformation as it relates to knives. I also know from personal experience that it's remarkably easy to chip most thin knife edges (side-load, impact-load, or otherwise), and it doesn't take much impact at all.

We may or may not be talking about a knife that needs to cut in the same way that either a jackhammer bit or a milling tool does... I suspect "neither". That remains to be seen, based on the OP's cutting requirements. Let's wait for the OP to clarify what he/she wants before we get any further off track.
 
chiral.grolim said:
Regarding INFI and Jim's tests, it matched a 154CM blade at 61 Rc but is steps below the high-carbide powder steels at the same hardness. At different hardness, I am not sure that you are really comparing the steels anymore, unless one steel just can't reach the hardness of the other (as Hardheart elucidated).

But regarding side-loading and charpy/izod impacts, those impact values correlate to cross-sectional area, don't they? As the area is reduced (as on a blade edge), the impact force required for fracture is also reduced. Side loading can be static or dynamic, it can happen slowly (testing plasticity and UTS) or it can happen suddenly, thereby calling upon impact toughness. When a blade slips against a hard object, however gently, the sudden impact is indeed an impact. When cutting cardboard boxes or carpet, blades can impact against staples - it isn't chopping but it is still an impact. Impact toughness plays a role in small knives as well as large knives. Or did I miss something?
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james terrio said:
hardheart, you're right to point out the important differences between gross impact and plasticity and yield strength. I do have a very basic understanding of the modulus of deformation as it relates to knives. I also know from personal experience that it's remarkably easy to chip most thin knife edges (side-load, impact-load, or otherwise), and it doesn't take much impact at all.

We may or may not be talking about a knife that needs to cut in the same way that either a jackhammer bit or a milling tool does... I suspect "neither". That remains to be seen, based on the OP's cutting requirements. Let's wait for the OP to clarify what he/she wants before we get any further off track.
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I think you are both correct, and I have no preference to steeling or grinding damaged edges. Chipping or rolling are both failures at the edge, so either brittle failure or plastic deformation bug me to no end. I don't think you can avoid both if you use knives hard enough, and you'll get one or the other just depending on the steel. The toughness you need at the edge doesn't seem to be as high as what you might need to prevent gross failure of the whole blade, it's tht steels much less tough than INFI work in knives large and small. Of course, most people have little need for the wear resistance we fancy in super steels as well.

I do have 3V in a folder (58 Rc) and a 4" knife (60), so toughness isn't something I avoid or anything.
 
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