Aus-8 and Rust

[Robert Ptacek]

I have a Gen 1? Endura,integral clip,in Aus-8 that i've owned for about 23 years.In the last 2 years it has started to get a couple spots of rust beginning.It never cuts food or wet stuff.I keep it wiped down with a Tufcloth and have attacked the spots with flitz but eventually they come back.I'm not overly concerned but more curious why after all these years it would start to spot.It spends most of it's time on my nightstand.

[Mike Blue]

Robert...(edit for correction)

Even stain resistant steels above the standard 13% chromium can corrode/oxidize given the right conditions. The only exception reported here is H-1. My suspicion is that the collective "we here" will not live long enough to see it, but the next generation will have someone who notices a rust spot on their H-1 Spyderco if the right conditions prevail. No, the knife world will not end because of it. But it will generate a lot of discussion about what we here didn't know now. LOL

Your conditions of cleanliness and care are within acceptable oxidation prevention practices. In this case it's not what you have or have not done. There may be a point on, likely below, the blade surface where an opening exists, not visible to the naked eye, that allows conditions to create a rust spot that you cannot reach with your preventative measures. It's taken 23 years for that to become evident.

It may be time for an above average penetrating oil to enter your ritual cleaning. I'd recommend G96 as I've seen it stop rust in its tracks. Before application of any oil you choose, warm the blade to evaporate any water that might be lurking at below surface levels. Even 100C/212F is not going to come close to affecting the heat treatment of the blade. But be careful. Put a drop of your chosen anti rust oil on the offending spots while the blade cools to help it penetrate. Then return to your 23 year successful maintenance program.

[Accutron]

Robert...AUS-8 has only 5% Chromium content. That means it's not close to "stain resistant."

AUS-8 has 13-14.5% chromium.

[Mike Blue]

Thanks Accutron, I stand corrected.

[jpm2]

I have a Gen 1? Endura,integral clip,in Aus-8 that i've owned for about 23 years.In the last 2 years it has started to get a couple spots of rust beginning.It never cuts food or wet stuff.I keep it wiped down with a Tufcloth and have attacked the spots with flitz but eventually they come back.I'm not overly concerned but more curious why after all these years it would start to spot.It spends most of it's time on my nightstand.

Either the heat treat has been altered or what it's exposed to has changed. Only you can figure this one out.

[pantagana23]

Rust spots on stainless steel depend on homogeneity of the alloy.

The only idea I would have here is that repetitive cleaning over the years exposed some parts of the alloy where it wasn't completely homogenous.

[Robert Ptacek]

I am not concerned so much but curious.It's enviroment and use have remained fairly constant through the years.It is just a head scratcher.I'll Flitz them again.I appreciate all your input.Thank You.