Toughness of M4

Djulbert

Djulbert

Joined
Aug 2, 2016
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68
My edc for the last few months has been a Ritter Grip, M390. Love the knife. It replaced a mini grip with 154cm.

The Ritter is a thinner blade than I'm used to, and I keep it sharpened at a lower angle which works excellent for cutting. When using it, if I accidentally hit something else besides the object I'm cutting, it chips very easy. This usually happens when I loan the knife to a work buddy.

I know the thinner blade and lower angle makes it more prone to chipping, but if it was M4 would it be that noticeable in chip resistance?


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In my experience with my 810 contego in cpm m4 I have not had any chipping problems I actually haven't had any rolling, chipping problems. It will ding the edge if you throw it into 3/8 in steel though :)

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M4 is a great steel. This is why it is pretty much the only steel used in blade sports. Now I would say if you are loaning your friends your knives and they are coming back chipped it is likely that your friends are not taking proper care of the knives you are lending them. They may be telling you "oh I hit like one staple or nail" and really they have been carelessly hitting every nail in the box. You shouldn't lend your nice knives to anyone, it is always a recipe for disaster.

Here is something important to note though. M4 can be a very tough steel which is why they use it in blade sports. However if you look at the hardness they run the M4 used in blade sport choppers at it is generally much lower than the hardness used in smaller pocket knives that offer m4. On most pocket knives they run the M4 around 62 HRC all the way up to 64-65 HRC. This is WAY harder than it is run in blade sports. Nevertheless M4 is still a very tough steel as many will attest that the Spyderco Gayle Bradley folder is an excellent working knife able to take buttloads of abuse. Just be practical with your knife. There is no blade that is going to be a good geometry and be able to whack galvanized nails without damaging the edge.

I might recommend a light sabre for your uses.
 
I don't like to let other people use my knife. But sometimes, I give.

For instance, today there was a leak on a plastic hydronic line. To get to where the line was, you had to climb 4 stories of stairs, climb a short ladder, and climb over a safety rail. Over the rail there was very little space, and my buddy was there trying to figure out how much pipe needed replaced. There was some foam insulation that needed removed. He asked for my knife. I could have made him climb back over the rail so I could get into the spot. I could have climbed back down and went down the stairs and got a utility knife from the van. It's about 90 degrees in the plant, and just decided to hand him my knife. While cutting the insulation, I seem him lightly hit a steel pipe clamp, which I later noticed but a light chip in the edge.

Just made me wonder if M4 would have handled it better. I realize it wouldn't stand up against hitting steel hard, but a slight "tap" against it it might.


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I would suggest grabbing an inexpensive Mora, Svord, or Hultafors Demo knife for lending out, and you keep your good knives to yourself.

M4 is a nice tough blade, but it will need more upkeep than m390/20cv/204p will, but it will be a bit tougher.
 
To answer your question, I will tell you how I found out how tough M4 is.

I was at a wedding reception, and they needed the long stems on a bouquet of two dozen roses cut shorter. I pulled out my Spyderco Bradley and went to work. I thought it should be a piece of cake, but I quickly discovered that it was taking a lot of force to cut through, much more than it should have. After I was done I discovered why. Each rose stem was wrapped with florist wire. I had been cutting the wires along with the stems. Worried that I had damaged the edge, I looked closely at it and discovered only one tiny flat spot.

M4 has better corrosion resistance than most people think. Sure, it's not stainless, but it is certainly nowhere near simple carbon steels like 1095.
 
For a folder, it has plenty of toughness, but you will sacrifice corrosion resistance. It is a great steel though!!
 
Actually, some people are switching over to Vanadis 4E or CPM 4V. CPM M4 takes a VERy fine stable edge, but it is not as tough as some other steels like 4V/4E, 3V, PD# 1, L6, INFI, etc.
Lapedog said:
M4 is a great steel. This is why it is pretty much the only steel used in blade sports. Now I would say if you are loaning your friends your knives and they are coming back chipped it is likely that your friends are not taking proper care of the knives you are lending them. They may be telling you "oh I hit like one staple or nail" and really they have been carelessly hitting every nail in the box. You shouldn't lend your nice knives to anyone, it is always a recipe for disaster.

Here is something important to note though. M4 can be a very tough steel which is why they use it in blade sports. However if you look at the hardness they run the M4 used in blade sport choppers at it is generally much lower than the hardness used in smaller pocket knives that offer m4. On most pocket knives they run the M4 around 62 HRC all the way up to 64-65 HRC. This is WAY harder than it is run in blade sports. Nevertheless M4 is still a very tough steel as many will attest that the Spyderco Gayle Bradley folder is an excellent working knife able to take buttloads of abuse. Just be practical with your knife. There is no blade that is going to be a good geometry and be able to whack galvanized nails without damaging the edge.

I might recommend a light sabre for your uses.
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With 3v/pd1 dont forget Cruwear in the mix, they are all brethren.
Much like the m390/20cv/204p are comparable, Cruwear/3v/pd1 are very close in composition.

Cruwear opens up a bunch of Spyderco's; Manix 2, PM2, Military, and possibly others for folders.
 
IIRC, some of the CruWear, ZWear, Vascowear, type steels are not PM steels so you need check.
NJBillK said:
With 3v/pd1 dont forget Cruwear in the mix, they are all brethren.
Much like the m390/20cv/204p are comparable, Cruwear/3v/pd1 are very close in composition.

Cruwear opens up a bunch of Spyderco's; Manix 2, PM2, Military, and possibly others for folders.
Click to expand...
 
As far as Spyderco goes, their initial batch of Cruwear was ingot, but the first gen didn't test as well and was tried in a CPM process and it was up to standards for the alloy.

The knives that have been made with Cruwear have all been CPM as far as I know.
There may have been a few that were released, but I am unaware of any of an actual number that (might have) been released, or even still in circulation (if some were released).
 
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I never had chipping issues with m390 blades, even thin ones .... but I didn't try to put a lower angle on them

IMHO the guys you are loaning your knife to haven't taken much care of it ....


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Dudes that are used to 56hrc AUS6 blades will almost always chip 61-62hrc super steel blades.
 
M4 has unique special toughness properties: it becomes chippy, crappy and easily damaged the moment it's held by a "mate" or "co-worker"'s hands.
Solution: avoid this undesirable sides effects by not letting "mates" handle your expensive blades :thumbup:
 
Don't loan your good knives, ever. Keep a beater or utility knife for people who don't have their own.
 
jdm61 said:
Actually, some people are switching over to Vanadis 4E or CPM 4V. CPM M4 takes a VERy fine stable edge, but it is not as tough as some other steels like 4V/4E, 3V, PD# 1, L6, INFI, etc.
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I like Vanadis 4E a lot. I have a couple of ZT 0180s, one of which I have really used hard, and 4E holds an edge incredibly well, and is astoundingly tough in my experience.
 
I like Vanadis 4E, too, and I will always choose 3V when toughness is going to be an issue.

You can also put a microbevel on the edge to help reduce chipping and without sacrificing slicing ability.

M4 is a great steel -- one of my favorites for a steel with well-balanced toughness and wear resistance. CPM M4 is considerably tougher than D2 and has better wear resistance to boot. And D2 is a great steel in its own right. M4 is better.

weartoughgraphweb.gif
 
Twindog said:
I like Vanadis 4E, too, and I will always choose 3V when toughness is going to be an issue.

You can also put a microbevel on the edge to help reduce chipping and without sacrificing slicing ability.

M4 is a great steel -- one of my favorites for a steel with well-balanced toughness and wear resistance. CPM M4 is considerably tougher than D2 and has better wear resistance to boot. And D2 is a great steel in its own right. M4 is better.

weartoughgraphweb.gif
Click to expand...

Don't put all of your stock into Charpy tests... The test reflects the alloys in a different setup than a knife edge allows.
On top of that, here is a quote from a thread about Charpy tests and data observed, you might remember it.
Twindog said:
Many thanks to cm_bushman for compiling these data. Great effort and very interesting.

But I worry about investing too much faith in these numbers because of the lack of sourcing or the credibility of the sources. And I worry even more about comparing steels without referencing the heat treatment, even though the hardness numbers are available.

I've had CPM-M4 hardened to 64 Rc shatter into three pieces on me from just hand pressure. Other CPM-M4, even harder, has proved remarkably tough.

Can you really compare 52100 steel elaborately and skillfully heat treated by someone like Ed Fowler to another maker that does a quick and dirty heat treat? Does heat treating by Bos really add no extra value to the steel? Is Dozier D2 really no better than D2 treated by a novice smith? I doubt it.

I have several blades in S30V and they don't all behave alike.

I suspect that if we gave multiple blades of equal geometry and in the same steel to multiple smiths, they would all test out differently; and the spread in many cases would overwhelm the differences intrinsic to many steels.
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NJBillK said:
Don't put all of your stock into Charpy tests... The test reflects the alloys in a different setup than a knife edge allows.
On top of that, here is a quote from a thread about Charpy tests and data observed, you might remember it.
Click to expand...


I think the point I was making in that old thread is that testing has to be consistent, and we were looking at a wide variety of Charpy testing where the details of the steel, hardness and even testing protocol were missing and where the testers were not the same people and were using different testing protocol.

I was also pointing out that heat treat is important, too.

The wear-resistance and toughness comparison chart that I posted is from Crucible and reflects a high standard of testing from a reputable steel company.

My M4 camp knife is heat treated to 64Rc, and it's taken a considerable amount of abuse -- mostly chopping -- without any damage. I've also had a bowie knife made from W2 by a custom knife maker that suffered edge damage on every chop into a piece of clear-grained, clean Doug fir. I've seen other knife makers chop through nails with their W2.

Heat treat is super important. But as for steel, CPM M4 is certainly a well-balance steel with high levels of both wear resistance, strength and toughness.

This is that M4 blade at 64Rc:


DSC01991_zps98a3ae12.jpg



Here's my other M4 blade heat treated to 64Rc:

DSC01614.jpg
 
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