15N20 rusting


Well-Known Member
I recently made a set of steak knives out of 15N20 for my brother. Chose 15N20 because I have a simple forge for heat treat and I could find steel thin enough for what I wanted. So I knew 15N20 would not be stainless but these blades rust pretty much on contact with anything mildly acidic. He cut a tomato and boom instant discoloration.

So I'm wondering if there's a suggestion to make them a little more rust resistant? Would a forced patina solve the issue? Since they are finished knives I assume vinegar would be the way to go? Any suggestions or thoughts are appreciated.

and boom instant discoloration.

Just discolored but not rusted? That's expected. You can't reasonably avoid it on most
non-stainless steels but it's not harmful.

You're on the right track that a forced patina will make it less noticeable because what
you're seeing the start of a natural patina. I've used both ferric chloride and vinegar
to get an initial patina but these days I'm more likely to just let one develop naturally
over time.
Thanks Dan. If it was my knives I would just let it form naturally as well. I tried to explain that to him and his wife, but they think the discoloration is problematic, so I figured i'd try something to minimize it. I think i'll try the vinegar to see how that plays out.


Charlie Lewis, a world class straight razor maker, has a Utub video a vinegar patina. Worth a watch. If they don't like their knives I'll swap them for some, nah, that wouldn't be fair. We have some Chicago Cutlery steak knives, standard carbon and wood, and they are looking "classic." Good luck, WDL III
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Thanks for the tip on the etching video Torque. He makes it simple and straightforward. I finally had time to etch and finish the set. I think they turned out pretty well. The etching really goes with these Kirinite handles.
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Also let them know the patina is a normal thing and to use a light coat of mineral oil to keep them from rusting.