M390 Corrosion test

BBW said:
sweet!!!!!!!!!! waiting with you for the result!!
Click to expand...

So here is the pic of the blade as it sat for over 24hrs I see red rust forming in a few spots:

Another view:




Here is a few pics of it right out of the saltwater:





Here is the blade after a fresh water rinse and cloth wipe... Virtually all red rust is gone.





The only place any red rust still is visible is on the tang right above where the lock bar insert would sit. I have not attempted to wipe it but I am almost certain a wipe would remove it. I'll wipe it in a few.
 
Over all, this chunk of m390 sat submerged in salt water that is more salty than any ocean for more than 24hrs.

All rust that was on the sides literally rinsed away. This steel should not patina under nearly any normal circumstances. Including neglect. That said different heat treatment will vary the steel significantly.
 
Here is the tang area that has some small areas that I have not attempted to wipe:



This is the only rust visible since the rinse. I have not attempted to rinse this part exclusively yet. I just wanted to document exactly what was rusted.
 
After running water directly over the tang and wiping with a cloth, all remaining rust is gone. Zero rust is visible. When I think about the specific spots that rusted the most, I believe for the most part they are places where other steels contact the m390. The detent hole... The tang...

The only rogue spot was on the side and that washed away instantly.
 
Man that is some nice testing right there!!!!! Now I'm confident (thanks to you) that my M390s would be ok at the beach in Florida
SWEET!!!!!!!!!!!
Thanks for putting the time and blade to do this!!!!!
 
m390 is my favorite steel, but now it's proven it's worth! Thanks for the testing, and follow up.
 
Hate to resurrect this year+ old thread, but I appreciate the testing done here. I was searching around for some info on M390 after noticing some small speckling all over my new DLT PM2. I’ve carried it since I’ve had it and I typically wipe it down and clean it frequently, mostly out of habit as I carry a lot of 1095 traditional knives and have to keep up on them.

Two days ago we were at a cook out and I cut up a hot dog for my toddler. He already had ketchup and mustard on it and I just cut it up for him. I wiped the knife off after with a napkin, but there was nowhere convenient to rinse it off or anything. I put it in my pocket and forgot all about it. Until today, when I took it out to cut something and noticed all these small specs all around the section I used to cut. The orange around the spots mostly wiped away, but the staining is still there. I'll try some flitz or barkeepers friend later tonight when I'm home from work, but I'm pretty bummed and hope these spots don't act as a catalyst to allow more rust to continue.

While anecdotal, my point I guess is the heat treat may cause certain blades to be more susceptible to rust under different conditions.

Pictures here:
https://imgur.com/a/oJjDjLi
 
Mustard is a good oxidizer. Some people use it to "patina" their carbon steel blades.
 
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Heat treat and contaminates in the steel are certainly factors. I'd stick that blade in something acidic like a lemon and let it set for awhile to see how bad it rusts out of curiosity.
 
Lol, not really looking further destroy this one. In fact I took some flitz to it last night and oiled it up a bit and it looks as good as new. I guess it was mostly superficial.

I was before however, under the impression that m390 wouldn’t rust unless there was some extreme neglect. I don’t consider what I did extremely neglectful, so now I’m going to be a little more cautious about how I treat this one.
 
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Nice test. Personally M390 would not rust. It is designed to withstand melted plastic (fairly corrosive) I think anything short of sulfuric acid or so would not really rust M390.
 
my benchmade 910 in m390 is a favorite of mine and I use it in the kitchen a lot. while I do clean the knives after use, it's good to know it can handle a lot and then some more. thanks for the experiment.
 
Thanks for the tests. They make me like my m390 blades even more than I already do. I ve had no problems near the ocean with that steel or 20cv or cts 204 .
 
Thanks for taking the time to do all this and post.
This is going to sound weird, but if you're up for it, would you test kiwi fruit juice and papaya? Two of the bladesmiths that I respect most have mentioned 2 or 3 times kiwi specifically. I don't want to mention the makers specifically because even though kiwi was singled out, they might have just used it as an example. Possibly just a language thing. It struck me as odd because most of us don't think of kiwi fruit as particularly acidic compared to things like pineapple or other citrus.
The only thing I can think is that maybe both have some enzyme. If you ever look on meat tenderizer, it lists papain as the main ingredient and some old timers I know swear by papaya for digestion.
Anyway, on 2 different supersteels that were severely rusted, kiwi and papaya were singled out as culprits.
I'd be interested to see if just slicing the fresh fruit and letting it dry for a few days causes any reaction.
I'll PayPal you a couple bucks if you are up for trying it out.
Thanks again, interesting test.
 
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