To M4 or not to M4...

[Albatross]

Where is the option to replace M4 with Cruwear?? :D Jade plus DLC Cruwear would be been a dream combo for me.

I think I put that option in your Cruwear thread. :D :p

[5-by-5]

I've loved M4 for a long time. I'm not buying rex45 is better. As mentioned they're so similar why change?

M4 rocks

[Albatross]

I've loved M4 for a long time. I'm not buying rex45 is better. As mentioned they're so similar why change?

M4 rocks

If the edge retention is similar, but the steel is easier to sharpen, and is slightly more rust resistant, why not?

The Rex 45 Military I own has been slowly developing a patina over the past few months, while my M4 PM2 began to show light rust around the spyder hole, within 3 days. That light rust was from the oils on my thumb, nothing more. To me, the added rust resistance makes the upgrade worthwhile.

[Larrin]

CPM-M4 has better toughness and edge retention when at equivalent hardness. There is no reason why Rex 45 would have better corrosion resistance.

[Albatross]

CPM-M4 has better toughness and edge retention when at equivalent hardness. There is no reason why Rex 45 would have better corrosion resistance.

This is true, however Spyderco runs their Rex 45 harder than their M4.

[TkoK83Spy]

I think MOST people would have trouble telling a difference between the two, maybe besides how quickly they patina. I'm cool with both, so I guess whichever ended up making the knife cheaper!

[Albatross]

Here's a new video from BBB, about M4 and Rex 45.

https://youtu.be/PzIEuz0ogoE

[Larrin]

I've loved M4 for a long time. I'm not buying rex45 is better. As mentioned they're so similar why change?

M4 rocks

If the edge retention is similar, but the steel is easier to sharpen, and is slightly more rust resistant, why not?

The Rex 45 Military I own has been slowly developing a patina over the past few months, while my M4 PM2 began to show light rust around the spyder hole, within 3 days. That light rust was from the oils on my thumb, nothing more. To me, the added rust resistance makes the upgrade worthwhile.

Your experience in different corrosion resistance is unlikely to have been due to steel difference.

[Sumdumguy]

I disagree that REX45 has more corrosion resistance than M4.

My REX45 PM2s blade was the same color as the handle within 2 hours at work. M4 on the otherhand, has only the slightest patina after a year of use.

Rex 45 has less carbon and the roughly the same chromium, you shouldn't see more rust, you should see less. The general consensus is that Rex 45 is less prone to rust than M4. My own experience, as well as others from this forum, have shown this to be true.

Since Rex 45 is a slight improvement over M4 in edge retention ...

I disagree. Rex 45 is harder, but wears quicker. At least with my Spydercos.

So No.

My own testing, as well as 4 others that I'm aware of, show Rex 45 with slightly better edge retention. Maybe it's possible you got one of the "softer" ones? Maybe it's not at 66-67 hrc, but 64-65. There were a few that were found to be in the 64-65 range, it's bound to happen from time to time. If you have multiple Rex 45 knives and and find M4 stays sharp longer, then I would assume you have a stellar example of M4.

I know what everyone says... I disagree.

In my experience M4 is far better at corrosion resistance. Idk if it's a body chemistry thing or what, but REX45 turned orange instantly and my Mantra barely has any patina after a year.

Enlighten me as to why that is.

[Albatross]

I've loved M4 for a long time. I'm not buying rex45 is better. As mentioned they're so similar why change?

M4 rocks

If the edge retention is similar, but the steel is easier to sharpen, and is slightly more rust resistant, why not?

The Rex 45 Military I own has been slowly developing a patina over the past few months, while my M4 PM2 began to show light rust around the spyder hole, within 3 days. That light rust was from the oils on my thumb, nothing more. To me, the added rust resistance makes the upgrade worthwhile.

Your experience in different corrosion resistance is unlikely to have been due to steel difference.

Could heat treat(good or bad) be the difference?

[Albatross]

I disagree that REX45 has more corrosion resistance than M4.

My REX45 PM2s blade was the same color as the handle within 2 hours at work. M4 on the otherhand, has only the slightest patina after a year of use.

Rex 45 has less carbon and the roughly the same chromium, you shouldn't see more rust, you should see less. The general consensus is that Rex 45 is less prone to rust than M4. My own experience, as well as others from this forum, have shown this to be true.

Since Rex 45 is a slight improvement over M4 in edge retention ...

I disagree. Rex 45 is harder, but wears quicker. At least with my Spydercos.

So No.

My own testing, as well as 4 others that I'm aware of, show Rex 45 with slightly better edge retention. Maybe it's possible you got one of the "softer" ones? Maybe it's not at 66-67 hrc, but 64-65. There were a few that were found to be in the 64-65 range, it's bound to happen from time to time. If you have multiple Rex 45 knives and and find M4 stays sharp longer, then I would assume you have a stellar example of M4.

I know what everyone says... I disagree.

In my experience M4 is far better at corrosion resistance. Idk if it's a body chemistry thing or what, but REX45 turned orange instantly and my Mantra barely has any patina after a year.

Enlighten me as to why that is.

This has made me wonder about body chemistry as well. Does one steel react differently than the other? I have no idea. My Rex blade barely has a patina, while my M4 began to rust, and you have experienced the opposite. I'm curious now.

[Larrin]

Could heat treat(good or bad) be the difference?

Maybe. I’d guess probably contamination or surface finish.

[Sumdumguy]

This has made me wonder about body chemistry as well. Does one steel react differently than the other? I have no idea. My Rex blade barely has a patina, while my M4 began to rust, and you have experienced the opposite. I'm curious now.

Here's a pic of my fairly well worn Mantra taken a few moments ago, just to prove I'm not completely nuts. (The stuff in the Spyderhole was some lint.)

It's almost impossible to get the patina to show up in a picture.

[anycal]

^^ My Mantra doesn't patina much at all, barely a hint of discoloration. Compared to my Native, which got a nice coating pretty easily. The blade finish appears to be a bit coarser on the Mantra. That may have something to do with it.

[fanglekai]

M4 will patina for sure. My GB1 has quite a bit of patina from using it. Look at the patina near the Spyderhole, for example.

[Tucson Tom]

M390 still seems to still have a bigger following and a more perceived value than 20cv.

Something I have never understood. Every knife I have in 20cv is superb. A candidate for my favorite steel.

The whole M390 hype irritates me, so I essentially boycott it -- though I understand it is probably almost as good as 20cv or cts204p.

[Tucson Tom]

As for Rex45 over M4 -- I voted yes, simply because I have quite a few knives in M4, and feel that it is time for something new.

I have one of the Rex45 sprints, and all I can say is that it is really good. Better than M4? Who can say? Not me anyhow, but it is a great steel.

Don't get me wrong, I think very highly of M4. I think it is funny though the people who admit they have never tried Rex45, yet want to champion M4. I guess all you can say about that is that people resist change and new things.

[GarageBoy]

I know everyone is going nuts over rex45 because it ran 67 hrc - but what's stopping m4 from being run that high? Do the components that allow it to be a hot work steel allow it to achieve a higher hardness?

[standy99]

I don’t think any steel has to replace M4 the variety of steels is what makes Spyderco Spyderco.

I do think Rex45 should have its own home like the M4 has the GB2
( Cruwear also )

[mb1]

Don't get me wrong, I think very highly of M4. I think it is funny though the people who admit they have never tried Rex45, yet want to champion M4. I guess all you can say about that is that people resist change and new things.

I had the same thought.

I think it’s important to note that the proposition in the poll isn’t to get rid of M4. It’s just an idea that would make REX45 more readily available. Kind of like how Cruwear used to be Sprint run-only steel. It is VERY good that is no longer the case!