Question about m4 and m390

J

Jack Lewis

Basic Member
Joined
Nov 24, 2007
Messages
99
I figured this would be covered somewhere between in past threads, but I'm having trouble finding an answer.

I'm trying to figure out whether m4 is indeed tougher than m390. The comparisons I'm seeing all focus on edge retention, with the two being equal or m390 coming out marginally ahead.

But is m4 tougher? Or is it roughly the same as m390, minus the high stain resistance?

Thanks!
 
Everything else being equal, I believe M4 would be considered tougher.
0de8c8ecbc6306badc0b7f4463e29a35.jpg


Sent from my Nexus 6 using Tapatalk
 
Trying to pin down every variable in a scientific way could quickly spiral out of control, so I'll try to keep it as clean as possible: Let's say two Paramilitary 2 blades with a factory geometry, hardened to whatever the going production standard is for each.

Thank you for any insight!
 
Thanks so much, Slauterhause.

Is it the tungsten that makes you think so? The molybdenum?

I'm practically illiterate when it comes to metallurgy.
 
Last edited:
Exactly, at least that's the way I understand it. Since it's a wash with the vanadium, the increased tungsten and molyBD in the M4 would put it on top in the 'toughness' Dept.



Sent from my Nexus 6 using Tapatalk
 
Mo, W, V make for a wear resistant edge .Cr in the 390 makes it stainless . CPM M4 is the one to use for knives .So both are "powder steels " . M390 for stainless and 'normal ' knife use and M4 for extra wear resistance .
 
Both are excellent steel with good edge retention. I'm pretty sure given both steel proper HT and most people won't notice any difference in edge holding.

However, CPM-M4 will rust much more readily.
 
mete said:
Mo, W, V make for a wear resistant edge .Cr in the 390 makes it stainless . CPM M4 is the one to use for knives .So both are "powder steels " . M390 for stainless and 'normal ' knife use and M4 for extra wear resistance .
Click to expand...

Mete, In M4, is the Wolfram (tungsten) held up in carbide form to primarily aid in working edge or does it serve a different function?
 
It's my understanding that M4 is in a totally different league of toughness when compared to M390.

My own personal experience with the toughness of M390 has been bleak. I've had chipped edges from doing routine cutting tasks on M390, 20CV, and 204p. The only other steel this has happened to me with is S30v. Maybe high carbide stainless steels just aren't for me. I haven't had my M4 blade long enough to compare, but I expect it to fare much better.
 
M4 is tougher then m390

It's the lack of chromium that helps with that toughness

But it doesn't work like that across the board with every steel.

3v has 8% chromium and is tougher.

But that's due to a lower carbon content at 0.8%

So as a general rule the lower both the carbon and chromium the tougher the steel.

Of course they're exceptions

Also, the reason why the heat treatment is also huge is because the structures that are created in the steel with all those alloys are determined by heat and how long the steel is held at certain temperatures and quenched will ultimately determine how the structures are arranged thus performance or lack thereof

So if your knife chips does it mean the steel is bad? Or it has a poor heat treatment

Nah.

There is still geometry to play with

also factor in if it's the right tool for the job.
 
Geometry ?Yes that's why some suggest S30V have a broader angle than others.
W,V,Mo are strong carbide formers so much ofit goes to formcarbides.
 
Chipping and M390
Click to expand...

I have been EDCing at work, for routine cutting cores, a Benchmade and where I would normally get some slight chipping while using 189 I have had zero chipping with the M 390 and better edge retention than my one S110V. I am very happy with my M390.
I have no experience with M4 but if it rusts I like it all ready. Serious positive comment.
 
I did an informal test of M4 vs. S110V in identical blade shapes and M4 did better for me. I have no firm information on toughness.

photo2014-11-13ab_zps6645e940.jpg



Put M4 in your pocket while sweating in the yard and it might rust:

photo%20777b_zpsby2caqmq.jpg
 
CPM-M4 is tougher than m390
CPM-M4 edge retention is better than m390

M4 HRC63-64
M390 HRC60-61
 
You must log in or register to reply here.
Back
Top