M4 and S90V micro chipping after cutting cardboard?

[CrimsonTideShooter]

I was breaking down boxes (only 2, neither had anything metal on or in them) so I decided to try my gayle Bradley and also my s90v para2.

I dis one box each, approximately 15 cuts per knife. After cutting I felt the edge on both knives with the tip of my fingernail and I could feel little catches in the edge. I looked at both of them through my 60x pocket microscope and sure enough both of them had little chips all along the edge that you couldn't see with the naked eye. What's the deal with this? Are these steels so hard that they are prone to chipping like that?

The GB was edge pro'd to 36 degrees inclusive, and the para2 was also EP'd to 36 but it also had a 40 degree microbevel on it from the sharpmaker.

 

[Jason B.]

Try a micro bevel.

The lack of lateral strength in the edge at the apex of the cutting edge due to its sharp V geometry will cause such problems as you are seeing. You will most likely need to use a higher angle or microbevels. That or only finish to about 1k.

Cardboard also comes in many flavors, some you could cut all day with little damage to the knife and others will tear away the edge before the first cut is done.

It could also be normal wear, these premium steels act different than what you may be used to. Break down of the edge from razor sharp too toothy "working edge" happens much faster and at a more even rate, to me your experiencing normal wear for edge type, steel used, and media cut.

 

[Ankerson]

High Vanadium Carbide steels like S90V will develop a toothy edge after awhile that will just keep cutting and cutting for it seems like forever.

It's a little different that what most are used to seeing.

Cardboard can be very hard on a knife blade depends on what the cardboard is like.

I have cut cardboard with ZDP and it literally tore the the edge to pieces in a very short time while S90V held up great cutting the same box.

 

[CrimsonTideShooter]

Thanks for the input. It's true that I'm not used to the high end steels, so I guess I was really confused about what was actually happening. I always thought micro chipping meant damage. It never crossed my mind that it might be normal edge degradation.

 

[Undertow82]

I'm so glad I joined this forum. I've learned so much in the short time I've been a member. I just wish I had joined earlier. When I get paid I'm gonna get my gold membership.

 

[EOM]

Whenever I get a new blade, I put a polished microbevel on it using a very fine ceramic stone or whetstone. It keeps it as sharp or sharper than the factory edge while strengthening the edge as well.

 

[Carlos]

That microserrated "toothy edge" is a signature of the S30V to S90V family. Love it or leave it -- I love it. If you want a high polish edge you are better off with VG-10 or even AUS-8.

 

[Joshua J.]

Thanks for the input. It's true that I'm not used to the high end steels, so I guess I was really confused about what was actually happening. I always thought micro chipping meant damage. It never crossed my mind that it might be normal edge degradation.

I haven't looked at my edge under magnification recently, but micro-chipping is not something I consider normal for any steel.
Try sharpening out the micro-chips and try again. If the edge consistently chips on the same material, as already suggested, use a micro-bevel to give the very edge a little more durability.