Spyderco Forums

Been wanting to do this for awhile, a direct straight edge retention comparison between these two steels. They are very close in performance, closer than some would believe. Both knives are CF Sprint run Military's sharpened to 400 grit Congress Moldmaster finish at 15 degrees per side. This leaves IMO the optimal edge finish for maximum edge retention and cutting efficiency.

The Test:

Slicing 5/8" Manila rope checking every 20 cuts for down force and cutting was continued until 20 LBS was reached. Starting force was 11 LBS for both knives and after 20 cuts both knives were at 14 LBS.

The Steels:

M390

C - 1.9%
Mo - 1.0%
Si - .70%
W - .60%
Cr - 20%
Mn - .30%
V - 4.0%

CPM S90V

C - 2.30%
Mo - 1.0%
Cr - 14.0%
V - 9.0%

M390

Cut aggressive with the edge finish and took some edge damage as expected as all steels have, it was still sharp enough to slice printer paper after testing.







CPM S90V

Very Aggressive with the edge finish and as with M390 it took some edge damage, but slightly less. Sharp enough to slice printer paper after testing.








Knives together.








Results:

Both knives performed extremely well as expected with S90V over M390 in the end by 21% or 460 to 380 cuts.

Very close as I expected it to be, under normal use most wouldn't be able to tell them apart depending on actual use unless they were pushed to the limit of edge retention. In that case the added Vanadium content of S90V at 9% over M390 at 4% would take over.

Nicely done Jim.

Those vanadium carbides do help with longevity.

It's a fun game to watch foundry's race, jump higher and run faster so we can improve the "edge".

sal

21% is not insignificant. Not sure how big a difference would have to be for a user to detect in real world conditions, more than that, I agree.

sal wrote:Nicely done Jim.

Those vanadium carbides do help with longevity.

It's a run game to watch foundries race, jump higher and run faster so we can improve the "edge".

sal
sal

Hi Sal,

Thanks. :)

It's been a long time coming and I wanted to use Military's to do it to give both the best chance at high performance and to keep the variables down. :)

Turned out as expected when they are pushed to their limit. :spyder:

xavierdoc wrote:21% is not insignificant. Not sure how big a difference would have to be for a user to detect in real world conditions, more than that, I agree.

You are correct, it's pretty close though, not like the 400% + differences I have seen in testing. :D

The question is, how different are the two from a sharpening standpoint? How much work does it take to reprofile the two? I came to this conclusion that for me these higher end steels are a bit of a waste since i don't mind touching up my edge everyday (i'm a sucker for that fresh off the stone edge) so if i could get this close to S90V performance and spend less time working on the bevels to keep them there, then i'd be very interested.

Nice Jim.

I've been waiting for you to run these two head to head. About as I'd expect, but good to see.

Thanks for doing it.

Ken

Evil D wrote:The question is, how different are the two from a sharpening standpoint? How much work does it take to reprofile the two? I came to this conclusion that for me these higher end steels are a bit of a waste since i don't mind touching up my edge everyday (i'm a sucker for that fresh off the stone edge) so if i could get this close to S90V performance and spend less time working on the bevels to keep them there, then i'd be very interested.

A lot will depend on what you are sharpening with, but in general say in reprofiling or repairing S90V is noticeably harder to work with.

Basic sharpening, neither is too bad with M390 being easier.

That's depending on what one is using as I said.

kbuzbee wrote:Nice Jim.

I've been waiting for you to run these two head to head. About as I'd expect, but good to see.

Thanks for doing it.

Ken

Thanks, results are as expected really due to alloy content, both are excellent steels that will cut for a very long time.

I'm using an Edge Pro with the standard stones it came with. I was concerned about 20CP but i found it to be quite easy to reprofile with the 120 stone, but it does seem to require a bit more attention at the very edge to get it as sharp as S30V.

Evil D wrote:I'm using an Edge Pro with the standard stones it came with. I was concerned about 20CP but i found it to be quite easy to reprofile with the 120 stone, but it does seem to require a bit more attention at the very edge to get it as sharp as S30V.

You will be fine with either, M390 will take less time to get screaming sharp than S90V (20CP).

M390 will take a blow your mind edge...

VERY cool. I love the M390 Millie, and wish I had an S90V one also. I will say that M390/20CV is still my favorite steel to date. Thanks Jim! :)

Very nice write up! Thank you for taking the time to put it all together and present it here. :)

SteelSnob wrote:VERY cool. I love the M390 Millie, and wish I had an S90V one also. I will say that M390/20CV is still my favorite steel to date. Thanks Jim! :)

Excellent steels all of them. :)

ChapmanPreferred wrote:Very nice write up! Thank you for taking the time to put it all together and present it here. :)

Thanks. :)

Thanks for that test Jim. 21% is a lot...but like you said, not a lot compared to 400%. Have you done the same test, head to head, with a S30V Military?



Hmm, I think that it is time for a 20CV Military.

Thanks for the test, it must have been tough on the arm... :)

I like both, but prefer M390 for its easier sharpening. Its also a little bit tougher than S90v at the same hardness, with better corrosion resistance, so IMHO its a slightly better all rounder.

Interesting. Thanks, Jim. The 21% gives some perspective on the categories in your review on BF. If I recall correctly, one S90v knife came in a category lower than M390 and another s90v, due to a minor difference in RC. Prior to this post, I had not wrapped my head around how important RC and how much variation in edge retention that may result. Thanks again.

DeathBySnooSnoo wrote:Thanks for that test Jim. 21% is a lot...but like you said, not a lot compared to 400%. Have you done the same test, head to head, with a S30V Military?



Hmm, I think that it is time for a 20CV Military.

Have 2 here in S30V, haven't planned on it, I could do one between S30V and XHP. :)

Jurisprudence wrote:Interesting. Thanks, Jim. The 21% gives some perspective on the categories in your review on BF. If I recall correctly, one S90v knife came in a category lower than M390 and another s90v, due to a minor difference in RC. Prior to this post, I had not wrapped my head around how important RC and how much variation in edge retention that may result. Thanks again.

Not sure of the hardness on the M390 knife, the S90V knife is at 60 HRC.

Very nice work. Thanks for the testing, Jim.