Will M4 develop a patina? And how does M4 compare to ZDP?

FlaMtnBkr

FlaMtnBkr

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Oct 20, 2004
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Hi

I bought a Benchmade 710 in M4 steel a while back and have not had the desire to use it yet. However, after using a new ZDP caly 3 I have been coming close to using it to try out the M4 steel.

That being said I have never been a fan of coated blades. I was wondering if I stripped the blade if I could get it to develop a nice patina that will be fairly durable and not immediately rust on me? I have read that some of the more complex carbon steels don't want to take an even patina and was wondering if M4 would be one of those?

Second, does anyone know how the M4 should compare to ZDP as far as the edge it will take and how long it holds it? Anyone know what hardness Benchmade ran these at?

Thanks!
 
M4 will take a nice even patina and make all other steels quiver in its sharpness. M4 also holds its edge very well though ZDP may hold one longer I think it would be hard to tell much difference in normal use.
 
I think BM does their M4 at 60-62, not really any harder than D2. I honestly don't know if M4 will develop a patina, but I believe it rusts pretty easily.

A friend of mine did some informal comparison of a BM 760 M4 & a Spyderco Para Military in CPM D2. He felt they were pretty similar in edge holding & hardness seemed pretty close while sharpening it.

I don't know what Spyderco does their CPM D2 at, but I'll bet it's pretty close to M4. Currently, I don't think you'll find any steel as hard as ZDP-189 at the moment. Depending on what knife manufacturer you read, ZDP seems to be at 65-67 RC. I think Kershaw SG2 & possibly 110V are the only ones that come close, but I think they're in the 62-64 range. I could be wrong, though.
 
Thanks for the replies.

Maybe one day I will decide to use it but I will probably just play with my ZDP for now.
 
I keep my Krein Ultimate Caper in M4 rust and patina free by wiping it down after every use and keeping body oils off of it. It gets extremely sharp, better than ZDP-189 by a fair margin. In my use I have found M4 and ZDP-189 to be very comparable in edge retention, no formal testing involved here. What I love about M4 is that amazing sharpness, it always seems a grit ahead of every other steel in sharpness. By that, I meat at DMT Coarse it is sharper than ZDP-189 gets at DMT Fine, and so on. It positively frightens most people that use it after 2000 grit Shapton Glasstones, and at .05 microns it is sharper than any other steel I have sharpened. It can take and hold very acute angles as well. I love ZDP, but I LOVE M4.

Mike
 
Wow, Mike, what you said about M4 is very tempting. Too bad nowadays it's very difficult to find a knife made with M4, am I right?
 
gunmike1 said:
I keep my Krein Ultimate Caper in M4 rust and patina free by wiping it down after every use and keeping body oils off of it. It gets extremely sharp, better than ZDP-189 by a fair margin. In my use I have found M4 and ZDP-189 to be very comparable in edge retention, no formal testing involved here. What I love about M4 is that amazing sharpness, it always seems a grit ahead of every other steel in sharpness. By that, I meat at DMT Coarse it is sharper than ZDP-189 gets at DMT Fine, and so on. It positively frightens most people that use it after 2000 grit Shapton Glasstones, and at .05 microns it is sharper than any other steel I have sharpened. It can take and hold very acute angles as well. I love ZDP, but I LOVE M4.

Mike
Click to expand...

This is really strnge statement. I sharpen both steel without visible difference in effort to hair whittling sharpness. I think this final sharpness can be done for any steel.

But I am confused how DMT coarse with 45 micron abrasives can affect M4 and ZDP189 differently? Results - depth of scratches from diamonp particles on the surface of both steels will be same.

Other question - how do you measure sharpness to say that one is sharper then another?

Thanks, Vassili.
 
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