Patina/stain on CPM 154

[Hyesouljah]

I cut up an apple for my dog earlier and it looks like my blade has formed a patina. I tried cleaning it with soap and water but still there.

The finish on the blade is a laser etched black finish. Is it normal for CPM 154 to patina like this?

Going to try a few things to see if it’ll clean off. Didn’t expect this blade to patina

 

[toker]

Apples are slightly acidic, so I'm not surprised that CPM154 has started to get a little patina. It's corrosion resistant, but not immune to rust or patina.

I like the look, so I would just use it and not worry about it. You can use some Flitz Metal Polish to remove the patina if you're really bothered by it.

 

[David Mary]

If you handed me that knife I'd scotchbrite the patina off in a minute, but I don't think I could hand it back until I fixed the edge and point as well.

 

[oldblu]

With >14% chromium I’d think that CPM 154 would not discolor from the acidity in an apple. Could dry grinding the blade on a wheel or belt, heating it up enough to de-temper the edge make this steel more susceptible to patina?
It sorta looks like that to me.

 

[The Zieg]

Hopefully not raising the dead here, but I'm curious whether this knife continued to patina or you cleaned it up. (FWIW, I like patina on my knives.)

Just wondering!