Rust on stainless PM steels vs rust on non-stainless PM steels

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Maximumbob54

Joined
Jun 10, 2024
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No, stainless does not equal rust free... What I mean is I've had a few recent instances of rust on some of my nicer stainless steel knives that are usually known to not have this issue and yet besides some patina I've not had rust on M4, K390, Maxamet and other steels that should be prone to rust.

I should also admit upfront that I tend to be a little more rough on stainless steels not doing much routine wipe down and oiling simply because they are a stainless steel. Over the decades of various flavors of stainless I've carried it's only Gerber's 420HC that's ever been a problem child with rusting. Buck's 420HC, Spyderco's AUS 6 and 8, Case's Tru Sharp (some kind of 420), whatever Victorinox uses, and more have never given me trouble.

But a short while back I had a Sebenza in S45VN with a couple of freckles and the edge eroded from carry in pocket in a leather slip. And I mean the edge was GONE. Not as it I had to strop it back. And now this morning I was going to carry a Para 3 in S45vn and I swear the edge has brown spots on it. I set it aside to check better this afternoon but I don't know what else it would be.

And yet the PM2 in M4, Tenacious in M4, Stretch and Delica in K390, or various Case in CV or CS hasn't rusted in my pocket with just a minimal wipe on my sleeve with done and occasional oily rag wipe down at the end of the day (when I remember).

And again, I know stainless doesn't mean rust free... I just find it odd to have this problem and only on a fancy PM stainless.

Does anyone else have issue with PM stainless rusting on them??? Or just for curiosity, does anyone else have steels that should be rusting that seem to ignore the trend???
 
My experience is similar to yours but I don't use many tools steels. My last two work knives Buck 420 and Hogue Magnacut get no rust with no maintenance. My Manix in s30 is better taken care of and gets the rust spots just like your describing. I do have some 01 and A2 tools but I keep them covered in oil,
 
BigMoney said:
My experience is similar to yours but I don't use many tools steels. My last two work knives Buck 420 and Hogue Magnacut get no rust with no maintenance. My Manix in s30 is better taken care of and gets the rust spots just like your describing. I do have some 01 and A2 tools but I keep them covered in oil,
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Interesting you've had this with S30V while mine have been S45VN.
 
Delgadonine said:
Your outdoor environment? Are you allowing it to enter your knife storage space?
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The Seb stays in the leather pocket slip but end of the day it and everything else in the pockets is set on the night stand to be reloaded the next morning. Air conditioned house with the humidity usually upper thirties to low forties. And again, the Case stockman or similar also in a leather slip is treated the same but with the occasional oily rag wipe down at least every few weeks. I try for weekly but confess it's more like when I remember.
 
Are your sharpening stones clogged with carbon steel dust? Gave them a good clean to rid the dust and sharpen the s45 again. It might just have been transfer of rust prone dust to your stainless blades.

It could also be that your sweat is strong stuff. Some people can make almost everything rust.
 
SharpBits said:
Are your sharpening stones clogged with carbon steel dust? Gave them a good clean to rid the dust and sharpen the s45 again. It might just have been transfer of rust prone dust to your stainless blades.

It could also be that your sweat is strong stuff. Some people can make almost everything rust.
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Shouldn't be the problem. I almost exclusively use the diamond plates on the WS Precision Adjust and wipe them off when I'm done. The Tormek wheel doesn't see much use but I dress it between uses so it shouldn't be clogged either. And neither knife has seen the Tormek because I'm still terrible with it.
 
May be a dumb question, but did you buy the Sebenza from a reputable dealer? There are clones on the market, and some of them may be made with the Chinese D2 or something else.
I certainly hope this is not the case, but I have gotten burned by clones before unfortunately
 
chevyrulez1 said:
May be a dumb question, but did you buy the Sebenza from a reputable dealer? There are clones on the market, and some of them may be made with the Chinese D2 or something else.
I certainly hope this is not the case, but I have gotten burned by clones before unfortunately
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It was bought second hand but came with all the original contents. If it's a clone it's the best I've ever seen since it has all the correct markings and the box contents are identical to what I've bought from Knife Center. And the Para 3 also came from Knife Center.
 
Can't say I've ever had a serious problem with rust or corrosion, and I don't baby my knives. My Marbles Fieldcraft in 52100 developed a light coat of rust on a moose hunting trip in northern BC, where it rained quite a bit. I had it in a Ziploc baggy as a backup and only discovered that when we got back. I had wiped it down with BreakFree CLP before putting it in the baggy so I was a bit surprised. As far as PM steels, I've not had any rust problems, albeit my GB2 in M4 has a few minor blemishes. Buck's 420HC is highly rust resistant -- I found a 119 lying in the bilge of a beached saltwater fishing boat a couple decades ago. The leather sheath was ruined but the knife showed hardly a touch of rust, and cleaned up very nicely. BreakFree CLP or plain old Vaseline work work pretty well for me.
 
Maximumbob54 said:
What do you do for your K390 and M4 that it's rusting? Do you wipe them down after use? Do you ever wipe them with oil or anything?
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No oil but I do wipe them down after use. For the most part the corrosion is only over the summer with pocket carry.

I have never seen a spec of corrosion on S30v.

I also have not seen any corrosion on Cruwear with a low temper ht but I have seen corrosion with a high temper ht.

A step further I have washed a Magnacut pocket knife off in the ocean after cutting open the stomach of a sturgeon that washed ashore, zero corrosion.
 
Alberta Ed said:
Ziploc baggy
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Similar enough but not really, my grandfather used to keep a couple of shotguns under his bed that he used most often at the skeet range. He left about a foot of the soft side case open on each one to "let the guns breathe" . He lived in the NV desert so he had a swamp cooler that I don't know how much but definitely added humidity to the air. He never had a spot of rust. I was always amazed when he would pull them back out and not a freckle of rust could be found. He let them breathe... ;)
 
I'm only an armchair metallurgist, not a chemist, nor am I the most diligent maintainer of my knives, but my collection is about as diverse as you can get. Very few of my blades have rust, like gross oxidation. Only one that even comes to mind is the severely abused Pakistani lockback I won at the fair when I was a kid. My childhood survival knife has some spots, but they're the least of its worries, Chinese stainless. I've got a bead-blasted M4 bayonet repro out of 90's SMKW with more spots than that, and it was only ever used as a paper weight and letter opener. I rescued a UC Hibben Raptor from Goodwill that looks like it sat on edge in a shallow pool or was left stabbed into wet wood, literally a line of fine rust an inch from the tip and discoloration that I can't buff completely clean.

Less than a handful of my good knives have so much as a freckle, regardless of material or amount of use. I keep them clean, but seldom oiled. I only sharpen as needed, and my needs aren't for razor thin edges.

Curiously, I do have more than one recently made example of "micro"(?) rust out of the box on stonewash finished blades. Namely one of the modern Case flippers, Marilla iirc, has just barely perceptible traces of orange at the inner edges of some of the jimping ridges and in the tiniest corner of the laser etched maker's mark. After noticing, I caught some reviews, and I'm not the only one. I like this knife a lot, have been carrying it pretty frequently, but also keeping an eye on those spots. I'm not terribly worried, more surprised than anything to see that on S35VN.
 
I've seen times where salt water didn't effect a knife, but seasoning on food reacted more strongly. Magnacut can sometimes patina, but resist corrosion from salt water. Sweat from some people can be more corrosive than others, too. Going from a cool, Air Conditioned house, to working outside in hot humid weather and then back inside can cause condensation to form and rust can start on carbon blades easily from the condensation.

I did a magnacut kitchen knife and it started to patina. I had used a scotchbrite belt for the satin blade finish. I redid the finish with a finer grit AO belt and scrubbed it thoroughly after re finishing the blade, no more patina. May have been some leftover dust on the blades from the belts? Never saw that before, but I guess it can happen!

Etched Makers Marks use an electrolyte solution that oxidizes with current, so it's a controlled rusting. That's why they may show as rust or rust starts there. The black is an oxide/form of rust. Laser etching may not do this as much?
 
chevyrulez1 said:
Odd, S45VN is supposed to have increased corrosion resistance to S35VN.
Not sure what would have caused that
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I think a LOT depends on the finish. A DLC, satin or even a higher-polish stonewash will do pretty well against rust, as long as it’s stainless.
In the hot, humid summer months in New England I’ve had 20CV form tiny rust spots around the pivot area from about a week of carry with no real maintenance.
The finish of that particular knife was a rough “working finish” which is basically a scratched-up bead blast.
S35VN ( less stainless than 20CV) has been fine on smooth stonewash and satin blades for way longer between maintenance in my experience.

My D2 Rat was fine for me, and my M4 Spyderco was not nearly as bad as I thought it would be (both were machine-satin blades).
 
Don't get me wrong, I've picked up rust on plenty of stainless including many PM steels. But overall I've still had way more rusting with non stainless...

Kinda ashamed, but my k390 Stretch 2 has been getting absolutely abused here lately. She's covered in oil right now on the night stand to slow the spread until I have time to get her cleaned back up lol..

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