K390 vs S690 which sould have better edge retention?

[CMP-40V]

I have heard that this two steel, 10V and M4 are leading at edge retention realm, and K390 and S690 are just upgraded version of them.

Assume that if both has optimum heat treat, which should hold the edge better? which one would be tougher? Thanks.

 

[cm_bushman]

I don't know about S690, but I edc a CPM-M4 blade and I've been using my K390 Mule in the kitchen and outdoors since I got it. I hope to do a review on it after I have a little more time with it.

For edge retention, neither steel really keeps that razor (hair-popping, tree-topping, etc) level of sharpness long, but both are great as far as usable, working edge retention goes. K390 completely outclasses M4 in this regard though. I use diamond abrasives, and going from 440C to 154CM to M4, I couldn't really tell a difference in sharpening, but bringing the angle down to 15dps on the Mule took about twice as long as it did on my M4 blade at similar hardness. I've noticed no loss of sharpness after a couple nights of prepping dinner and carving in the mean time.

As for toughness, M4 is tougher than most knife steels with this alloy level, and my M4 mini-Grip sharpens well with less burr formation than most steels I've tried (this is at ~63HRc), and it holds an edge without chipping for the most part. I've had small (as in grains of fine sand) chips cutting thicker plastic and after dinging the tip on some pavers, but this is to be expected and after sharpening through the factory edge there have been no more chips. From what I could put together on K390, (I couldn't find any Charpy C-notch data), it has roughly 25% more impact toughness than 10V, which puts it in S30V range, somewhat less than M4 but still tough enough that I would not worry about it. I've not really put my Mule to task yet, but after carving some cocobolo and dried bamboo, I've seen absolutely no edge damage.

In short, M4 is slightly tougher, and K390 is far more wear resistant. It is the first steel that I felt was truly a worthwhile upgrade from 154cm, s30v, etc., and just from initial testing, it seems much like M4 but with double the edge retention. They even took a forced vinegar patina the same way. I hope this helps!

 

[CMP-40V]

I don't know about S690, but I edc a CPM-M4 blade and I've been using my K390 Mule in the kitchen and outdoors since I got it. I hope to do a review on it after I have a little more time with it.

For edge retention, neither steel really keeps that razor (hair-popping, tree-topping, etc) level of sharpness long, but both are great as far as usable, working edge retention goes. K390 completely outclasses M4 in this regard though. I use diamond abrasives, and going from 440C to 154CM to M4, I couldn't really tell a difference in sharpening, but bringing the angle down to 15dps on the Mule took about twice as long as it did on my M4 blade at similar hardness. I've noticed no loss of sharpness after a couple nights of prepping dinner and carving in the mean time.

As for toughness, M4 is tougher than most knife steels with this alloy level, and my M4 mini-Grip sharpens well with less burr formation than most steels I've tried (this is at ~63HRc), and it holds an edge without chipping for the most part. I've had small (as in grains of fine sand) chips cutting thicker plastic and after dinging the tip on some pavers, but this is to be expected and after sharpening through the factory edge there have been no more chips. From what I could put together on K390, (I couldn't find any Charpy C-notch data), it has roughly 25% more impact toughness than 10V, which puts it in S30V range, somewhat less than M4 but still tough enough that I would not worry about it. I've not really put my Mule to task yet, but after carving some cocobolo and dried bamboo, I've seen absolutely no edge damage.

In short, M4 is slightly tougher, and K390 is far more wear resistant. It is the first steel that I felt was truly a worthwhile upgrade from 154cm, s30v, etc., and just from initial testing, it seems much like M4 but with double the edge retention. They even took a forced vinegar patina the same way. I hope this helps!

I haven't had experience with K390 yet but I do have several knives which made of M4 and 10V, really looking forward to try the K390. Anyway Thank for the input:thumbup:

 

[michaelm466]

K390 should be just below 10V with a little better toughness, both (10v and K390) will be in a different (higher) league than other super steels even (M4, S90V, M390, etc)

 

[The Mastiff]

Do you mean S693, the high speed steel equiv. of M4?

S690 is a high strength structural plate steel for ships etc. best I can tell