Best stainless steel for use in salt water?

Awesome stuff.
I'm not looking for a pointed dive knife. I'm hesitant to even refer to them as a knife as much as a tool. I use a SS doube ended snap link for a tank banger. I'd only use a knife for cutting or scraping crud off a mooring cable or trying to get a shell out of a coral head or something.

Good to know on the Titanium. Not really into the whole migraine thing.

I'll have to start exploring more of the "new knifemaker" threads as well.

Thanks again everyone.
 
What do you divers do after the dive ?? Rinse equipment in fresh water or deionized water ? Keep out of sheath ?
 
I've ground literally thousands of pounds of titanium and have never had a migraine. However the smoke (any smoke from grinding metal) is bad for you. I prefer to grind titanium slowly so there are very few sparks and smoke.

I spoke to a metallurgist about 440C corrosion resistance. He said a good portion of the chromium is tied up in chromium carbides. The remaining free chrome is just barely enough for 440C to be considered stainless. I've looked for information to back this up, but I've been unsuccessful. Does anyone know if this is true?

Chuck
 
Hey, Chuck. I hear that Z-FinNit might be an awesome new stainless steel. What do you know about it? I think there is some guy forging it for his kitchen knives...
 
mete said:
What do you divers do after the dive ?? Rinse equipment in fresh water or deionized water ? Keep out of sheath ?
Click to expand...

After a dive you always rinse off ALL of your gear with fresh water. The care of anything you submerge in ocean water really isn't any different than a hunting knife that goes into a fresh kill carcass.

Both salt water and blood has about 3% salt content. I find that interesting from an evolutional point. Our blood has about the same salt content as ocean water.
 
Alpha Knife Supply said:
I've ground literally thousands of pounds of titanium and have never had a migraine. However the smoke (any smoke from grinding metal) is bad for you. I prefer to grind titanium slowly so there are very few sparks and smoke.

I spoke to a metallurgist about 440C corrosion resistance. He said a good portion of the chromium is tied up in chromium carbides. The remaining free chrome is just barely enough for 440C to be considered stainless. I've looked for information to back this up, but I've been unsuccessful. Does anyone know if this is true?

Chuck
Click to expand...

Chuck,
Everyone doesn't have that response to grinding Ti, as in your case and I've been told it's the light and or the smoke that causes that from a couple of other makers and this was over a decade ago that I had this experience. I have a colab of folding knives coming up that does involve grinding Ti so I thank you for the slow grind tip and will be spending some time researching this problem very soon.

As far as your question about the free carbides in 440C? I have never heard that and have always considered and used good ole 440C as the grand daddy of Martinisic culinary steels, prized for its stainless properties in my culinary & hunting knives?

I am not a papered metallurgist by any means so I can't debate what that man said?
 
A Mastersmith has been forging a nitrogen stainless steel called Z-FiNit. Here are the results:

RaderZ-FiNite-chef01-s.jpg


RaderZ-FiNite-chef02-s.jpg


We will be releasing the Z-FiNit soon. Several knifemakers have been testing the steel. The test results are looking very good.

Only one person was crazy enough to forge it. I think the integral stainless bolsters look great.

Chuck
 
Alpha Knife Supply said:
I've ground literally thousands of pounds of titanium and have never had a migraine. However the smoke (any smoke from grinding metal) is bad for you. I prefer to grind titanium slowly so there are very few sparks and smoke.

I spoke to a metallurgist about 440C corrosion resistance. He said a good portion of the chromium is tied up in chromium carbides. The remaining free chrome is just barely enough for 440C to be considered stainless. I've looked for information to back this up, but I've been unsuccessful. Does anyone know if this is true?

Chuck
Click to expand...

Verhoeven's "Metallurgy of Steel for Bladesmiths & Others who Heat Treat and Forge Steel",
discusses this in detail in the, IMO, very hard to follow appendix. The simple answer is, yes.
The appendix basically compares 440C to AEB-L and explains why AEB-L is better for knives.

Here's a link to the pdf: http://www.feine-klingen.de/PDFs/verhoeven.pdf
 
Chromium - carbon ??? The amount of carbon and chromium available for making it "stainless " is certainly effected by by the final composition of free chromium .Other elements also enter the picture . Some make a study of this but I don't have any numbers .Search this and other forums. These things also show up with complex steels when you see choices in tempering temperature . For example an S35VN can be tempered at 400 F or 900F .400 F will result in better corrosion resistance.
From a practical view I've always had the practice of keeping my knives clean and dry.When hunting I carry paper towels to do this. In preparing food , especially acidic ones , a simple rinse in hot water will remove most problems if you have to wait before further cutting.

Chuck, Z-FiNit -- Composition , who makes it ?
 
Sorry for the thread hijack :-) I'm liking the Z-FinNit so far and think it could definitely make for a great dive-knife material. I dove, off and on, for about ten years and the thing that I always heard horror stories about were of divers treasure-hunting or crabbing around the piers (in Puget Sound) that would get hung up in webs of old fishing line. I carried two crappy commercial "dive-knives" and a large, serrated Spyderco folder and always made sure they were very sharp.
 
Michael, I'm loving that dive knife- you could spearfish and slice up the sushi right there on the sea floor!
 
Ha ha. I needed a big knife like that because my dive "buddy" would secretly zip-tie on strips of bacon to my BC when we went Ling Cod spear-fishing and I could never figure out why they were attacking my back and my buddy always returned with a full bag. Should have made sushi out of him ;-)
 
I'm looking for a knife that I can swim in the ocean with and not have to worry about rusting or damage that comes at a reasonable price, any suggestions for that?
 
Michael - can you give us more info on the Z-FinNit? I am looking for the BEST material (price no object) for a high end sailing knife. I originally planned to use M390 but that isn't very available. Latrobe 20CV isn't very available either. Chuck is supposed to be getting something which is chemically identical but I haven't seen it yet. I would also use it for skinning knives. Thanks.
Tim
 
I handled the scubapro mako yesterday. Not bad but I don't like the retention clip on the sheath. Seems like a two-handed job.
The shop had the leg strap version which I'm also not big on. Would rather secure it to my harness somewhat out of the way.


Definitely know about rinsing and not leaving in the sheath. Figured that out with the medical shears I have. They're pretty much garbage now.
 
Been a while since I've been on here.
I still haven't gotten around to doing this but Titanium sounds like a viable option.

Holding an edge isn't super important. If I have to cut something it's a rare occasion. If I do, I can' always sharper it after a dive.
The biggest thing is corrosion resistance. Where I dive, especially, the salinity is really high. Even with rinsing, things tend to get cruddy.

How difficult is it to grind Titanium?
Do you need special equipment to do it?

I'm pretty much want to try to replicate the profile of the Boker Cop Tool if I do this and then see what improvements could be made from the design.
 
I recently decided to make a knife from stainless. I wanted it to be capable of being submerged in salt water without staining. I did quite a bit of research and decided on Z-FiNit for stain resistance and toughness. I got it from AKS, great bunch to deal with.
I usually forge blades with hand tools but I've been told that this stuff requires a lot of force to forge so I went stock removal on it. I'm not set up for powered stock removal so I've worked this steel with files, hacksaw and angle grinder.
I must say it hasn't been too bad to work using these tools. I should ad patience to that list.
Hoping to get it sent to peters for ht this week.
The handle will be G10, attached using marine grade epoxy and titanium pins.
I would say that would be the best attachment option for the tool your trying to make as well.
Good luck!
 
Chuck at AKS,
How would M390 (which I understand you are getting with the can ground off) compare with Z-FiNit for toughness at Rc 60?
 
tim37a said:
How would M390 compare with Z-FiNit for toughness at Rc 60?
Click to expand...
I have not tested a Z-FiNit knife at HRC 60. Everything I have is at 59. Using M390 at HRC 60 is a waste of good steel, I would not go below 61.

Comparing Z-FiNit at 59 to M390 at 60, Z-FiNit is much tougher.

Chuck
 
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