CPM 440V .....corrosion resistance

pillshovel

pillshovel

Gold Member
Joined
Jul 5, 1999
Messages
1,343
I know where 440V stands in the edge holding department, but is it more or less resistant to corrosion that say ATS55 or ATS34? I'm sorry if this has already been addressed.



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Chad
 
Chad - in "Q" fog testing, at the 6 hr mark, ATS-34, ATS-55 and CPM-440V run pretty close in corrosion resistance. At the 24, 48 & 72 hour marks. 440V was a little worse in corrosion resistance than both of the ATS variations (less than 10% diffeence). Hope that helps.
sal
 
You know, I was a little surprised at that. In ATS-xx a lot of chromium is tied up in carbides, leaving less for rust resistance. I figured in 440V, most of the carbides are vanadium, leaving plenty of chromium for rust resistance. Maybe the 2+% carbon is what's bringing it way back down.

Oh well, guess that's why we do tests!

Joe
 
I just got my Bladeforums.com Native. Scary sharp out of the box and superb fit and finish. Best I've seen and in Spydercos that's saying a mouthful
smile.gif
The G-10 scales fit my hand perfectly.

Now, that being said the blade had some light rust stains that quickly rubbed out with WD 40. Never seen that on a new fresh from the box knife--much less a spyderco. After reading this thread, I understand the problem.

The native will be my daily carry and worth every cent of $100, but I will keep it carefully oiled. A little extra care is worthwhile for such a magnificent blade!
 
Joe :

Maybe the 2+% carbon is what's bringing it way back down.
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That is exactly what it is. The most corrosion resistant steels have almost no carbon (less than .1 %). There is much more to corrosion resistance than just Cr content.

CPM has 420V tested at the same level of corrosion resistance as 440C which is very high. 440V comes up 4 times lower on a salt spray test because there is not enough Cr left to spread out in a uniform enough amount with the necessary concentration to form the required protective surface film. 420V has Vanadium carbiding instead of Cr, which has the benefits of harder carbides anyway, and leaves the Cr free for corrosion resistance.

And non of these come close to the corrosion resistance of austenitic stainless steels because there will be no C forming carbides as it all remains in the austenite matrix thus pretty much all the Cr is there to provide corrosion resistance.

-Cliff
 
Very interesting about the 440V. I have not had any problem with rust on my Military. I carry it almost exclusively now and it gets a lot of sweat on it. The steel of the knife I carried before was ATS-34. It always had surface rust after I carried it. As a matter of fact, any ATS-34 knife I carried would develop surface rust after I carried it, especially if I had been sweating.

I am curious as to why the 440V doesn't rust after I carry it, the way ATS-34 does. Based on the information, you would think my sweat would burn holes through the 440V. Is it possible that either steel has something in it that either makes it more or less succeptible to my sweat?

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Paranoia is only smart thinking
when everyone is out to get you.




[This message has been edited by Dirk (edited 01 September 1999).]
 
Dirk :

Is it possible that either steel has something in it that either makes it more or less succeptible to my sweat?
Click to expand...

Assuming you are human, probably not. Bottle some and send it to Spyderco R&D for testing.

I am curious as to why the 440V doesn't rust after I carry it, the way ATS-34 does.
Click to expand...

Surface finish, tempering, and simply the frequency/way you used the blade would all effect corrosion resistance. Also as you break in a blade the corrosion rate will increase significantly as surface wear sets in. Because of this a new 440V blade would be more resistant than an old ATS-34 one.

-Cliff
 
I think I'm human, though it has been questioned.

You think Sal would want me to send him my sweat?

I think the break in period of the steel is the most logical answer. From my high school chemistry, I remeber people will produce sweat with different pH levels and different chemical content based on diet and other things. I was thinking that maybe a higher or lower content of a material in the steels may have inhibited a chemical reaction with my sweat. You know, a certain amount of a chemical will do one thing, a little more or a little less wil produce completely different results.

I will keep an eye on the 440V and see what happens as I carry it more.

------------------
Paranoia is only smart thinking
when everyone is out to get you.


 
Dirk :

I was thinking that maybe a higher or lower content of a material in the steels may have inhibited a chemical reaction with my sweat.
Click to expand...

In general, a more corrosion resistant steel would avoid a reaction with your sweat for the same reason that it avoids rusting from the atmosphere and other enviromental concerns.

-Cliff
 
Dirk - Did the ATS model you are speaking of have double liners? G10 has a certain amount of porosity that may be assisting in "drying the persperation" (animals sweat, men perspire & women "glow").
sal
 
Sal, it did have double liners. That is rather interesting about G-10.

Oh, did you want any of my "persperation"?

------------------
Paranoia is only smart thinking
when everyone is out to get you.


 
Dirk - No thanx on the "persperation". We won't "sweat" the small stuff, but it was a "glowing" offer.
sal
 
Rim shot please.

------------------
Paranoia is only smart thinking
when everyone is out to get you.


 
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