S30V and rust.

rs422

rs422

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So my buddy hands me his bump and it has rust on blade. He says he left in an old car in the rain and it sat for 3 day in water next to metal. So I took it home to see what I can do with it and surprised that S30V would rust so easily. First thing I did before taking it apart was to wipe it down with some militec to see how bad it was and what do you know it all just wiped right off with just hard rubbing. Seem the rust was from the car metal rusting not the knife blade, it was just dirty. Three days in water not bad.

My buddy is very happy with the good news.
 
rs422 said:
Seem the rust was from the car metal rusting not the knife blade, it was just dirty. Three days in water not bad.
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I can't agree to that. I have experienced 2 types of corrosion on S30V. The one you described- where I only get some surface rust which can easily be wiped away. So I am very sure that this is what you experienced....

The other type is galvanic corrosion, which will result in deep pitting. The galvanic corrosion I experienced was with a S30V blade with DLC coating. The high humidity and the microscopic perforations in the DLC coating (matt finish) started a galvanic corrosion and it rusted like crazy!

Saying that, a smooth clean S30V blade spending 24 hours in salt water will get rusty- but only with a "easy to wipe away" surface rust. :)

Jorgen
 
I agree, it was the blade rusting, not the car.

It must have been some kind of agressive rain. San Diego, this is a dry area away from the sea isn´t it? Not so familiar with the US geos.
 
Blop said:
I agree, it was the blade rusting, not the car.

It must have been some kind of agressive rain. San Diego, this is a dry area away from the sea isn´t it? Not so familiar with the US geos.
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agreed. S30V will rust, if exposed to saltwater. not as easily as D2 or the carbon steels, but easier than VG10. I'm told the heat treat is also important.
 
Yes that does make more since that the S30V did rust just at the surface. The pattern of rust looks like they were formed on the blade. Good to know that surface rust cleans up easily. I told my buddy to get a Tufcloth and use it if he is going to expose the knife to moisture, that's what I put on every knife I own when not in use. You got to love the forum, lots of good folks to chase ones ignorance away.
 
In my experience S30V rusts a lot easier than some of the more popular corrosion resisitant steels........it doesnt rust easily, but in comparison to 440C it develops surface rust much more readily.


You CANT have everything!!! :eek: :rolleyes: :eek:
 
Just another 2 cents worth. In my experience, how quickly, or not, S30V rusts also has a lot to do with the surface treatment. A bead blasted or satin finish blade may rust a whole lot quicker than a conventional production level polished finish which won't do as well as a mirror polish finish and the "stonewashed" finish we're using on the RSK Mk1 seems to add another level of rust resistance. FWIW...
 
Just thought I'd chime in here.
the better stainless (I THINK) have higher carbon and more likely to rust than 440A, AUS6, etc. It's all part of life's trade offs.
 
Ok, everyone missed the obvious here... rs422, your buddy has been determined by the MDKCFS (Mongo Department of Knife Care and Family Services) that he is an unfit parent of said Kershaw Bump, and must remand custody of said knife to me immediately. ;)
 
Blop said:
I agree, it was the blade rusting, not the car.

It must have been some kind of agressive rain. San Diego, this is a dry area away from the sea isn´t it? Not so familiar with the US geos.
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San Diego is normally a VERY dry area right on the coast of the Pacific Ocean.

This year has brought record rainfall to Southern California, though...
 
Mongo said:
Ok, everyone missed the obvious here... rs422, your buddy has been determined by the MDKCFS (Mongo Department of Knife Care and Family Services) that he is an unfit parent of said Kershaw Bump, and must remand custody of said knife to me immediately. ;)
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Well he's not going to be happy about this but I'll let him know, but he may just run!
 
Based on the S30V steel properties it should have some pretty good corosion resistance. Chromium, Copper, Molybdnum, and Nitrogen all help in corrosion resistance. There is a high amount of Chromium and Molybdnum and a small amount of Nitrogen in S30V. That kind of tells me that this steel will have as much resistance to rust and corrosion as pretty much anything else we carry in our pockets.

Based on the property content of the steels out there S30V looks like it should be better than VG10 and the AUS steels for corrosion resistance. VG10 has no Nitrogen in it but a slight bit more Chromium. The AUS steels have less chromium (AUS10 is slightly more), far less molybdenum and 0 nitrogen content. It looks to me like S30V should be a good one to carry and not have to worry too much about compared to some of the other more popular steels out there.
 
STR said:
Based on the S30V steel properties it should have some pretty good corosion resistance. Chromium, Copper, Molybdnum, and Nitrogen all help in corrosion resistance.
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As I understand Cromium may be taken away by Carbon - with high Carbon content it may be less Cr left to protect surface.

Thanks, Vassili.
 
nozh2002 said:
As I understand Cromium may be taken away by Carbon - with high Carbon content it may be less Cr left to protect surface.

Thanks, Vassili.
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True, the Cromium bonds with the Cabon in the heat treat to make some of those spiffy carbides. They are nice and hard, but like it says up a lil higher, more carbon = more rust, and more carbon = harder blade. Thats the trade you make.

Glad it came clean for you

Ben
 
I have been carrying my Chinook for the last few days since getting it. The other day my wife and I worked pretty long and hard all day moving dirt and rock. I was sweating pretty profusely by the time we called it quits. I noticed when I took all the stuff out of my pockets to take my shower that the blade on my knife was covered in moisture. I wiped it off and then put it back on my clean pants. No rust on it so far. I've been checking it after every day of carrying and have not seen any signs. It may have to do with how long it goes unchecked more than anything else.

Steve
 
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