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

[Crag the Brewer]

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..

View attachment 2805103

I think a little Barkeeper's Friend and a hot pot of coffee might help....

 

[Maximumbob54]

Before I clean her up any:

So strange.

 

[Seedy Lot]

Before I clean her up any:

So strange.

With ht there is potentially a large difference between corrosion resistance between high and low tampering. Larrin often talks about this and I saw it myself when I tested a bunch of steel for corrosion.

My guess is since that knife has a PVD coating that the temepr was high which would also mean that the corrosion resistance of the steel has been reduced because of the secondary hardening effect pulling chromium and molybdenum out of solution.

I have seen rust on a PD1 Spyderco that I stripped off the PVD when I would normally not see the corrosion with a Cruwear knife with low temper.

 

[Maximumbob54]

Some time and patience on the strop and she's more than close enough:

 

[The Mastiff]

It sure looks to me like contamination from a sharpener or strop began that edge rust.

 

[Seedy Lot]

M Maximumbob54 I reached out to a friend who lives in Australia and asked him about his S45VN knife I gave him. This guy is an avid hunter and professionally runs backpacking trips and outdoor education.
Here is what he had to say about corrosion, "S45VN has been exceptional. It’s had days in the wet. It’s spent days in my pack bloody and has never had a sign of rust."

 

[SharpBits]

Could it be something you cut? Some material will oxide red orange and look like rust, but will actually just be on the surface of the steel.

 

[Maximumbob54]

It sure looks to me like contamination from a sharpener or strop began that edge rust.

I guess never say never.

 

[Maximumbob54]

M Maximumbob54 I reached out to a friend who lives in Australia and asked him about his S45VN knife I gave him. This guy is an avid hunter and professionally runs backpacking trips and outdoor education.
Here is what he had to say about corrosion, "S45VN has been exceptional. It’s had days in the wet. It’s spent days in my pack bloody and has never had a sign of rust."

This has been until very recently my same experience.

 

[Maximumbob54]

Could it be something you cut? Some material will oxide red orange and look like rust, but will actually just be on the surface of the steel.

Not sure what it would be. Even if I slice an apple I still clean off the knife. But again never say never.

 

[SharpBits]

Not sure what it would be. Even if I slice an apple I still clean off the knife. But again never say never.

Might be worth a call to Spyderco to see what they say. They might want it back so they can investigate.

 

[Maximumbob54]

Might be worth a call to Spyderco to see what they say. They might want it back so they can investigate.

Trying to see if I can recreate the problem with a few other knives and this one. S30V, S35VN, and a pair of S45VN knives up for this hopefully minimal sacrifice.

 

[RPZIP]

I have had rust appear on stainless knives - and guns. On guns it has been revolvers, rust forming under the grips. With synthetic grips I started smearing a layer of grease all over the grip frame before reattaching the grips.

I have a Victorinox Trekker that aquired a rust spot on the side of the main blade. It had been sitting out in the open at home and I think it was no doubt from condensation. Two other Trekkers - no applied protectants just in a bag with other knives - no rust.

I have a Spyderco that has rusted badly around the pivot from just sitting bagged for many years. Another one had a barely visible spot on the side of the blade.

I have noticed a very long time ago that whereas carbon steel will rust easier than any stainless, stainless will often suffer pitting.

My primary EDC, Kershaw Skyline in photo, is AUS8 I believe. I have had it for a long time - guessing 15-20 years. I think I lubed the pivot once, maybe twice, and only ever clean it with dish soap and water, or if anything gummy on the blade with rubbing alcohol. It has some rust on the blade, especially right in the corner of where the lock engages which is a difficult location to clean. I couldn't get a photo of that spot with my lousy phone camera.

 

[Maximumbob54]

I think I lubed the pivot once,

I keep a needle oiler with some 3in1 to occasionally lube the pivot on most of them.

 

[RPZIP]

I keep a needle oiler with some 3in1 to occasionally lube the pivot on most of them.

That's what I should have been doing

 

[Maximumbob54]

It's only been a few days, but how long should it take to see corrosion if it's from the strop???

 

[SharpBits]

It's only been a few days, but how long should it take to see corrosion if it's from the strop???

Probably needs some sweat to get the ball rolling.

 

[Eliteone2383]

I put a coating of frog lube on my knives. Depending on how much I carry a knife I'll coat it weekly or monthly. I use my knives for food so I can't use non food safe oils.

 

[Maximumbob54]

Probably needs some sweat to get the ball rolling.

I'll give them a good rub down after I work out tonight.

 

[Maximumbob54]

Juicy:

Figured I'd add another sacrifice.