How is cpm M4 vs. INFI

D2 is little more than half the toughness of A2 at 60, and about 1/4 the toughness of 3V at 58 Rc. M4 is twice as tough as D2 at hardnesses ingot D2 cannot achieve.

I think L6 is something like 75 ft lbs, which is close to 3V, and 5160 is supposed to be tougher.
 
I really don't know about INFI but M4 is really tough, and is often taken up to 65 Rc wich is much harder than INFI, and can take a thinner edge and can hold it longer. the increased toughness of INFI is ofset by the increased hardness of M4
 
Nebulae said:
...and is often taken up to 65 Rc wich is much harder than INFI, and can take a thinner edge and can hold it longer.
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Agreed, but that's not the "toughness" in discussion.

Nebulae said:
the increased toughness of INFI is ofset by the increased hardness of M4
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??? How, those are rather different applications. In simple words tough knife can chop through the hard medium, withstand twisting and prying, hard and thin edges with M4 @65 HRC definitely will break...

Don't get me wrong, I have nothing against super hard, thin edges and I have quite extensive collection of the knives with 64 HRC and above with very thin edges, kitchen or not, but I'd never use any of those for many things I won't hesitate to use my Busses for.
 
INFI steel will flex at hardness levels required for edge holding.
Instead of chips and fracturing you will see flexing and repairable edge rolls.

Never had a problem getting INFI sharp either:thumbup:
 
flex in steel has nothing to do with hardness, just geometry. Rolling is bending, which occurs past the elastic range. Flex is within the elastic range, bending and chipping/fracturing happen after.
 
In my experience, M4 wins in sharpness and pure edge holding, INFI wins in rust resistance, toughness (not by very much) and easy of sharpening.
 
What are some of the knives that use M4 steel blades? Any small fixed blades?
 
d.weglarz13 said:
I know that most Blade Sports cutting competition knives are made of M4, but they are alittle too big for me. .
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Somewhere here on BF I read that those Competition Cutters made of M4 have to be retired after some period of time as the steel work hardens under that intense use.
 
hardheart said:
what is the measured toughness of INFI? Is it more than M4, 3V, 5160, A2, or L6?
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I'm not sure INFI has ever been measured but it should be comparable in toughness to 3V. The impact toughness results don't always correlate with real world results though, we just know that both INFI and M4 are really tough. You won't be able to break an INFI blade or an M4 competition chopper by smashing it against a rock or shooting it with your Glock (take necessary safety precautions of course). To break the steel you basically have to tear them apart.

udtjim said:
What are some of the knives that use M4 steel blades? Any small fixed blades?
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The M4 Mule and that new Benchmade M4 fixed blade. Spyderco has a great heat treat for M4, my Benchmade M4 doesn't seem to perform as well. I rehardened mine so it's all good now.
 
steelnut said:
Both steels treated to the same hardness,
INFI will flex and roll with hard use, M4 will fracture and fold long before INFI:thumbup:
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Like S30V chipps right :rolleyes: Please someone show me a pic of fractured M4.......What in the world makes everyone think M4 is so brittle?
 
knifenut1013 said:
Like S30V chipps right :rolleyes: Please someone show me a pic of fractured M4.......What in the world makes everyone think M4 is so brittle?
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People probably say M4 is more brittle than INFI because it's usually heat treated to a higher hardness than INFI. That's why it has such good edge holding abilities. I think that if both steels were heat treated to the same hardness, someone wouldn't be able to tell the difference between the two. Perhaps at higher hardnesses M4 might edge out INFI in edge holding, but not by much. Perhaps at a lower hardnesses INFI might edge out M4 in toughness. All in all in a 4-8 inch fixed blade, the differences between the two probably wouldn't be obvious.
 
safetyman said:
People probably say M4 is more brittle than INFI because it's usually heat treated to a higher hardness than INFI. That's why it has such good edge holding abilities. I think that if both steels were heat treated to the same hardness, someone wouldn't be able to tell the difference between the two. Perhaps at higher hardnesses M4 might edge out INFI in edge holding, but not by much. Perhaps at a lower hardnesses INFI might edge out M4 in toughness. All in all in a 4-8 inch fixed blade, the differences between the two probably wouldn't be obvious.
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And thats the problem, people have a hard time understanding that M4 is very tough at RC 63. I know theirs lots of love for INFI but I would still put my money on M4.

heh, M4 is as tough as O1... if the O1 is at 60 and the M4 is at 63 :)
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knifenut1013 said:
Like S30V chipps right :rolleyes: Please someone show me a pic of fractured M4.......What in the world makes everyone think M4 is so brittle?
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ive gotten chips with both s30v and s90v.

s30v sebenza developed a chip on the edge, i have no idea how. it has only cut cardboard and paper.

same with an s90v military.

entirely possible they chipped when striking something like concrete, but i have no recollection of hitting that type of material with either blade. i dont "hard use" my folders.

easily repaired, but both chipped nonetheless.


i have never chipped 154cm, d2, ats34, infi, or any other steel i have owned, fixed and folder (no infi folder, yet) alike.
 
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