Storing semi-stainless tool steel knives in cars

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Karl H

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Apr 24, 2020
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I have a CPM 3V (7.5% Cr, 1.3% Mo) fixed blade that I would like to store in the center console of my car, when I am not using it. I would prefer not to rely on oils or desiccants to prevent corrosion.

For reference, the particular knife in question is a Benchmade Puukko. I have both the original sheath and a kydex sheath from Armatus Carry. The only time I have noticed any rusting on CPM 3V is when cutting acidic foods. I live in the Colorado front range, a relatively high and dry environment, but the relative humidity still does occasionally reach 100%.

Even if you don’t have experience with 3V, I would also be interested in your experience with other semi-stainless steels: D2, M4, Rex 45, Cru-wear, Sleipner, etc.
 
You know, I keep an RMJ breaching tomahawk in my trunk. That's 80CRV2 with no chromium at all in the alloy. The blade is cerakoted, but the edges are untreated. I'm kind of curious what I'll see in the long-term for that, myself.
 
If humidity occasionally reaches 100%, there might be a chance of some moisture condensation on surfaces. Whether or not that would affect the interior of your vehicle, I wouldn't know.

I did have one experience with a Victorinox SAK that I'd forgotten was stored in a toolbox in the hardshell-covered bed of a pickup, when living in central Texas years ago. It had been there long enough to rust as the result of condensing moisture outside. Granted, it was regularly much more humid there than I'd expect in someplace like Colorado's mountainous regions. But if any moisture does condense and stay on surfaces for a few hours, that might be an issue for some blades. I figure, if a very rust-resistant steel like that found in a SAK can rust under such conditions, then anything can.

With a knife stored in the console, I'd assume it'll be seen & inspected regularly. So, as long as you're getting a look at it every few days, or more frequently, there may not be much to worry about. The bad stuff happens when knives get stashed away and forgotten for a long while.
 
nickycat said:
I'd look into something like these VCI poly bags and/or these plastitabs.

Remember that all "stainless" steels will corrode and most folks wouldn't consider 3V to be "stainless". Also, the finishing of the blade affects corrosion resistance properties.
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I think I would opt to use food safe oil on the blade or desiccant, rather than VCIs, if I need a corrosion inhibitor. But personally, I would just prefer to just wipe/grind off any superficial rust, as long as there is no deep pitting.

I do think it is possible that 3V will be sufficiently corrosion resistant that infrequent water condensation will not cause significant pitting. Condensed water in a car doesn’t have chlorides or other ions that can depassivate the chromium oxide layer.

I cannot find any corrosion test data for condensed or deionized water, so it is hard to know for sure. Semi-stainless tool steels, like 3V also have a lot of Molybdenum in solution, which adds significantly to the general corrosion and pitting resistance of these steels.

In Larrin’s calculations, you can see that the pitting resistance of 3V should relatively close to that for CTS-XHP. 3V is much closer to being a stainless steel than a carbon steel (like 1095).
knifesteelnerds.com

Corrosion Resistance Testing of Stainless Knife Steels - Knife Steel Nerds

New corrosion tests of a range of stainless knife steels that I used to improve the corrosion resistance rating system. Which steels are best?
knifesteelnerds.com knifesteelnerds.com
 
1) use the Kydex sheath. Note that Kydex can melt when it gets too hot, so store it under the seat or similar.
2) either make sure the knife is clean and dry or rub it with an oily cloth that you keep close by - much like you would do with a hand-gun.

I have a 4V knife stored like this in my bike's tool bag in a saddle bag, and a Rex 45 knife in my car's center console for years - no issues whatsoever. And 3V is more corrosion resistant than either 4V or Rex 45.
 
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I’d use Renaissance Wax and call it good, he’ll, any type of car wax should be fine. Simple protection. And shiny too !
 
Karl H said:
In Larrin’s calculations, you can see that the pitting resistance of 3V should relatively close to that for CTS-XHP. 3V is much closer to being a stainless steel than a carbon steel (like 1095).
knifesteelnerds.com

Corrosion Resistance Testing of Stainless Knife Steels - Knife Steel Nerds

New corrosion tests of a range of stainless knife steels that I used to improve the corrosion resistance rating system. Which steels are best?
knifesteelnerds.com knifesteelnerds.com
Click to expand...

A picture might help :) Note how close my favorites 3V/Cruwear/Infi ("A8 mod" in the chart) are to - say - S30V.

i-GcfpVnP-X3.jpg
 
GAGL said:
(stinkt = stinks)

haha,yes,it has a certain smell to it. i apply only a thin layer with a rag.

it's the best solution i've found, to protect my blades from rust and it's food-safe. just make sure to keep it away from your phosphor-bronze washers.
Click to expand...

I love it. Great for guns, too. Plus - on knives - it also works for G10 scale maintenance.
 
I would worry about dew if you keep your car outdoors. You might go out just before dawn and check for condensation on metal objects inside the car and inside the console.

D2 is on my no-buy list because of rust, even though I habitual wipe off blades after use and keep them in a dry house. But I live in Florida where the weather is often damp.
 
000Robert said:
What do you mean by, "G10 scale maintenance"?
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Well I found another thread about it. I have a knife I bought many years ago that has some kind of scales on it - I'm not sure what they are. But the scales got nasty and rubbery on the outside. It would stick to my fingers and stuff. I tried everything to clean them up with and the only thing that worked, was acetone. Acetone made them look brand new again.
 
Old-time machinists kept their precision tools in wooden tool boxes. It seems to have a moderating effect regarding humidity changes and condensation as opposed to metal or plastic. They would put blocks of Camphor in them, which out-gasses and provides some sort of vapor barrier, I believe. I got some camphor blocks at an old-fashioned drug store near me.

Wipe a little lip balm or edible wax or lanolin or such on the blade. That will help.
 
Oh, don't store a knife long term in a leather sheath, especially one that is chrome tanned.
 
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