A good steel for salt water diving?

SkagSig40

SkagSig40

Joined
Feb 1, 2001
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I have a friend that dives in salt water quite a bit and he is looking for knife that will hold up well in salt water. Right now he has a Under Water Kenitics dive knife that is made of 420 ss and it rusts badly even in a 1 hour dive. I clean it up for him all the time and keep telling him buy a Ti knife so it will never rust! He dosn't want to spend the money on a nice ti knife like a Mission so what is the next best thing to Ti? 440C? He has to have the pry/chisle tip and serrations and he likes the gut hook too for cutting line. Any knives out there like this you might know of? I'm going to try to get him to spend a couple hundred on it if I can but he is cheep when it comes to spending $$ on knives so well under the $200 mark is great also! Thanks!:)
 
...A plastic knife. :D

No, seriously, any knife with a high Molybdenum, chromium and Vanadium content will be good for salt water. I have a Tramontina sport knife which holds up fine. Any diver's knife should be suitable. Even so, it should be rinsed in fresh water immediately or it will develop rust spots also. It should be dried thoroughly and a thin layer of silicon spray/oil should be applied when not in use.

Then....take two Aspirin and call me in the morning...:D
 
Get a low carbon stainless steel, 440A is better than 440C for that application. It is surprising that the AISI 420 blade rusts, it is a very corrosion resistant steel. If that can't hold up I would be surprised if any blade steel would. You may have to use Ti, Talonite or get a decent coating.

-Cliff
 
Hi,

I don't think Ti will be an ideal knife material. It is corrosion proof, but Ti can only be heat treated up to 40's Rc. Meaning : it doesn't hold any edge. When you get a Ti knife for general use, make sure it has a serrated edge.

I would advise you to check S30V. I know many people whose fishing/fillet knives are made of S30V. Holds a great edge, and one of the best corrosion resistant.

Good luck.
 
Originally posted by Cliff Stamp
Get a low carbon stainless steel, 440A is better than 440C for that application. It is surprising that the AISI 420 blade rusts, it is a very corrosion resistant steel. If that can't hold up I would be surprised if any blade steel would. You may have to use Ti, Talonite or get a decent coating.

-Cliff
Click to expand...

I was surprised to see the 420 rust also the first time I saw it! Maybe it is a bad batch of steel? His Father has a Dive knife made of 300 SS I think and it held up much better with no rust on the same dive.
Ti is softer but is very strong and will pry and dig well. It should stay sharp enough to cut you out of any problems as long as you maintain the edge every dive.
Thanks all for the help! ;)
 
Yep, I agree with the sentiment that if 420 is rusting on you, you probably have to get away from steels. Titanium or something like talonite (cobalt-based metal) would work, but now you're talking bigger $, unless you go with the less expensive (and lower performance) cheapie titaniums like the ones enkidu mentioned.
 
Something like 17-7PH sould be ideal for a dive knife, since it can be hardened to 54-55RC to hold an edge reasonably well, yet has 7 percent Nickel and 14 percent Chrome for high rust resistance. The only production dive knife that I know of is this one:

http://www.buckknives.com/products/details.php?ID=33

The 300 series stainless steels are sometimes used for dive knives, but these can not be hardened enough to take and hold a good edge. The dive knives made of 300 series steels are excellent for prying and chiseling ect.


-Frank
 
To get functional edge holding for Ti in regards to rope and flesh cutting, leave it with a filed edge. It will be very aggressive and last for a decent amount of time, and can be maintained with a simple butchers steel. No it won't last as long as a decent steel knife, but S30V will not stand up to an enviroment that has a serious effect on AISI 420.

-Cliff
 
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