Tough steel that will cut nails in half?

flatgrinder

flatgrinder

Joined
Dec 20, 2005
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I'm making a tactical knife (blade length: 6.5", stock size: 1/4", edge thickness: 0.030") and was wondering what is the cheapest and toughest steel out there (with the best edge retention)? Air hardening or carbon steel, it doesn't matter.

Basically, if I were to chop a 1/8" thick mild steel nail in half, which commonly available steel can do it without significant blade damage? 5160? 1095? O1? Hardness? (I know L6 is pretty good, but it's pretty hard to find). How does S7 hold up? Is it worth it? Or would 5160 work better?

Any advice would be appreciated! Thanks! :thumbup:
 
I got 5160 to chop on a mild steel bar without significant damage to the edge, not really a hig performance cutter though, really for heavy duty targets. if you grind a cold chisel style "edge" on any well HT'd blade, it will cut steel. Won't cut cigarette paper and stuff, but it will cut steel.
 
Try M4. Saw it in action at the Central Texas Knife Show and 4 guys used the same knife and at the end of the contest it still shaved hairs.
 
Problem with your question is that you are asking two different things. Cheapest and toughest? 5160 is cheap, M4 is tough.

In any case,the cost of the steel is a minor part of the cost of a knife when time and equipment are taken into consideration. And if it is to truly be a tactical knife, quality and performance of the steel should be far more important than cost.

As Sam pointed out, any steel can be made to cut nails. It is in the edge geometry and HT. I have,however, never seen a tactical knife that was designed to protect against an attack by a box of nails. The target is a blade that has a high enough edge angle to hold up to rough use, and still be sharp enough to cut well. The standard tests are:
Cutting Sisal or Manila rope.
Chopping through 2X4s.
Shaving hair (or slicing paper).


5160 is cheap and tough. Right now it cost almost as much to deliver it as the steel costs.It is easy to work with and home HT is easy.
D-2 is very tough.It is harder to grind , more costly, and the HT is not for many hobby makers.
M4 is tough and gets wicked sharp. It is the preferred cutting contest steel right now.It is not cheap, and the HT is very specific.
Lots of other steels would do,also. Most will have vanadium and other added alloys. This increases the cost. 3V, 10V,etc. would work. CPM S__V steels would be good stainless choices.

The HT is as important in a tactical knife as the material. The balance between toughness and hardness is achieved there.

Do some homework (yourself,not by asking someone else on the forums). Look at the steel specs for several types and pick the one that fits your :
abilities
equipment
budget
(and most importantly) the job the knife will ACTUALLY perform.

Stacy
 
i use cpm3v in my OB knives that are 3/16 thick
not sure if it helps but i have one coming back from the sand box for a sheath (didnt have time before to get one made) he loved the blade and beat on eit and yet it still has the edge i put on it he was impressed. now that he is back in the states he ordered a hunter in 3v for boar (might get tot see the blade on OLN)
 
I agree with Stacey specifically WRT the bevel angle. Pretty much all knife steels would be harder than and cut into mild steel. The longer you want that edge to hold, the higher your bevel angle. The trade offs are obvious.
 
An inexpensive Chinese alloy:thumbup:. I have a pack of hacksaw blades that go through nails really quick, they are made from an unkown alloy from China and are pretty cheap. I also own a couple of $5 crobars that get nails out of my way even quicker and they are made from an even cheaper Chinese mystery metal. I always say that if you want a hint in choosing an alloy, just look at what industry is using for that application, in this case Harbor Freight tools from China seem to be well suited for nails. But now if you want a steel for knife use, other applications and alloys could be considered.;)
 
Thanks for all the replies! :thumbup:

I was just wondering if the performance (for something such as M4) really justifies the cost over 5160. Say the cost is 3 times higher, is the performance really 3 times better? Or isn't there a discernible difference? The reason I ask this is that I've made knives from CPM S30V and haven't been all that impressed for the cost, I wouldn't say that it's that much better than ATS-34.

I've used D2 before at HRC 60, and it has chipped terribly when I've used it as a chopper on hardwood. O1 is much better, IMHO. I'm asking if 5160 is good because, I've made a hunter out of it, grind lines didn't match up perfectly at the ricasso, so I tried to destroy it. It is one tough SOB. I can't chip the blade, I tried flexing the blade, but it came back. Maybe I'll try sledgehammering it through a couple of nails, see if I can crack/ chip the blade.

Or maybe I should be asking if anyone has actually compared steels for tactical use? ie. Ground out identical knives in different steels and put them through the same battery of tests.

P.S. I used "nails" as a reference because I had a customer state that he wanted a "tough" knife that would "cut through barbed wire/ razor wire that was secured to a post." Figured if I put a 1/8" thick nail on a block of wood and chopped that in half without much edge damage and it would still cut manilla rope, he would be happy. Or should I just tell him it can't be made affordably and send him along to Busse Combat with their INFI steel? :confused:
 
If he wants to cut through barbed wire / razor wire... sell him a small pair of 5" wire cutters that fit in the sheath behind the knife, and sell him a quality knife for cutting... and charge an outrageous price for the custom sheath to hold the two tools at once.

Cutting wire is trivial with a pinching action, but is exceedingly laborious if you try to 'chop' it, particularly because the wire is flexible. Different tools serve different purposes.

http://www.sears.com/shc/s/p_10153_12605_00945077000P?vName=Tools&keyword=wire+cutter
 
Justin.Mercier said:
If he wants to cut through barbed wire / razor wire... sell him a small pair of 5" wire cutters that fit in the sheath behind the knife, and sell him a quality knife for cutting... and charge an outrageous price for the custom sheath to hold the two tools at once.

Cutting wire is trivial with a pinching action, but is exceedingly laborious if you try to 'chop' it, particularly because the wire is flexible. Different tools serve different purposes.

http://www.sears.com/shc/s/p_10153_12605_00945077000P?vName=Tools&keyword=wire+cutter
Click to expand...
thats about the best way i can think of doing it as i have cut com wire with my spyderco but in a "close the knife on the wire way" but chopping wire not realy a good plan
 
I was just reading this review:

http://cutleryscience.com/reviews/bm_e.html

"The blade was chopped into several sizes of nails resting on a 4x4 pressure treated block. The nails would be driven into the wood from the force of the impacts and cuts made up to about one quarter of the way through a 3.5" common nail, the edge was just blunted from the impacts. A 510 g ball pein hammer was used to enable the knife to chisel cut some 3.5" common nails. As the wood kept collapsing under the nails, the best that could be achieved was a cut about half way through. These various half dozen poundings put small dents in the edge, from one to two mm wide, the damaged region was up to 0.015" thick."

"The blade was then chopped into the head of the hammer. The knife made large cuts into the head, about one millimeter deep, and up to one centimeter long. This did no visible damage to the knife, just blunted it. A piece of a concrete block was then whacked that into bits, the hits were heavy enough to break the concrete apart and produce sparks. The rock contacts mashed the edge down, and produced abrasion lines in the edge. A lot of impaction had taken place, but no direct fracturing. The tip was then stabbed into the pieces a half a dozen times, breaking them. Some tip impaction, nothing significant, less than half a millimeter."

And another one:

http://cutleryscience.com/reviews/busse_basic.html#cutting

I think I'll just tell the guy to buy some INFI. I don't think any other steel will stand up this much abuse. He was just looking for a custom knife that could take some abuse for half the price of a Busse. Plus, I don't want to deal with the knife breaking and all the hassles involved. Thanks anyway guys! :thumbup:
 
Faltgrinder, your answer is literally right under you nose as it is best described in your signature quote "How a knife is ground will determine how it will cut, steels do not cut, geometries do." I personally would shy away from a customer who wanted to misuse knife like this, but if I proceeded I would choose any good impacting steel that would resit deforming while totally disregarding keen edge holding and then grind it somewhere between a hatchet and a chisel. You could indeed use any cheap steel if you just made the final bevel steep enough.
 
Klein makes excellent side cutting pliers , mine is a 9" with hardened cutters [much better for steel]! Someone also makes a universal tool for barbed wire -hammer, cutter,staple remover -all in one.
 
flatgrinder said:
I've used D2 before at HRC 60, and it has chipped terribly when I've used it as a chopper on hardwood. O1 is much better, IMHO. :
Click to expand...

I know you guys are all more experienced makers than me, but it sounds like you want a ballerina and a weightlifter all rolled into one. 60RC just *sounds* a bit on the hard side (=brittle) for a knife you are using essentially as an axe, to hack hard materials?

Tell the guy to buy TWO knives... he gets what he wants... you get to sell two knives :)
 
Ya know D2, as mentioned above, can be tougher than it's reputation would make you think.

This can be a topic of heated debate, and it was the topic when Cliff Stamp was banned, so I'll try not to step on any toes here. But it is my opinion that your D2 blade that chipped out wasn't heat treated right.

I don't have its specs in front of me, but I recall that its best impact toughness (not the same thing as torsional, but I don't remember that number) occurs around a 515 temper and GOES DOWN from there. So soft D2 is kinda stupid IMO. And perhaps so is its secondary hardening hump when used in knives. There are other ways to get around retained austenite than a high temper.

I have cut nails in half with thin ground very hard D2 on several occasions using a hammer. So it may not be a super tough steel, but it ain't too brittle either. At least in my opinion, which was formed upon heat treating and testing D2 and using D2 as my EDC. I'm not recommending it for this application, but since it was brought up, I thought I'd give my .02
 
I've found that it's not just toughness, but also strength (hardness) is required or the edge will roll. Batoning through a nail, rolling is a huge issue. So you want something that tough at high hardnesses. CPM 3V and M4 are both very tough at 62+ rc.

I have also batoned D2 through copper, and the edge held up just fine. However, if I try chopping (rather than batoning), the edge chips. 5160 and 1084 both fares significantly better. 1084 is cheap, tough, and can get very hard. Watch out for the embrittlement region during heat treat though.

I know knives are not meant to cut nails in half, but it teaches us what the specific steel is capable of.
 
M4 it is a high speed steel which means that it is able to cut thin metal very fast as too produce high temps from friction at 65 Rc it is still tough. problem is it is expensive, but I think that it is worth it.
 
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