Colors on stainless steel with 30w fiber

[Vasek Matyska]

Hey yÂ’all!
I have 30w fiber and Im testing all the materials and settings I can and I figured I can mark stainless steel cutlery with some colors. I was under impression only MOPA laser could do it. My mistake. Recently I found youtuber (Jeffrey something) that shows you can do it by unfocusing your lens few milimeters, recently IÂ’ve done it with lens absolutely focused, horay.
But I found out it’s kinda not stainless anymore when I mark stainless steel cutlery with black or colors and then put it into washing machine, some kind of rust appears you guys have any idea why is that? Is it ‘coz of the chemicals in the tablet or something else? Only water seems not to have same effect. I could send some pictures when I get to the pc.
Thanks for the replies and have a nice one!

[Matt Schrum]

From my refinery work, I know that some grades of stainless steel exposed to high temperatures can rust (and some can even become slightly magnetic, hello 316 welds)-- though I learned that in the context of stainless that was heated up for being near a weld. I'm not sure how the temperatures compare for that vs a laser.

Partway down this page, this metal wire basket maker alludes to the same:https://www.marlinwire.com/blog/what...-vs-316-vs-330
"In other words, you can expose grade 304 alloy steel to temperatures of up to 1,598 °F for short periods of time without ill effect, and for extended periods of time in temperatures of up to 1,697 °F. However, this can compromise the corrosion resistance of the metal, making it more susceptible to corrosion damage from exposure to moisture."

I would imagine that some other grades of stainless might be better behaved than what you've worked with so far, but I don't have and specific suggestions.

[art olin]

A variety of colors can easily be obtained on stainless steel from both the Q-switch version and the MOPA versions. Laser marking methods are divided into the following three major categories.
A - black or color marking method - marks the target surface with black or color by heating the surface, oxidation marking, change of metal structure due to heat affected zone from laser process
B - engraved marking method - removes the top surface of the metal by etching away material
C - cold marking rust-proof damage-free method - colors the surface while leaving the oxide film intact.
The smoother the mark from the laser process area the better it will resist rusting. However, it will eventually rust, and exposing it to salt, water, or chemicals will speed up the rusting process. Rusting is related to the heat your laser applied to the metal and the change in structure of that metal in that area. If you want to eliminate rusting on the metal’s laser processed areas, you need to graduate to UV marking - cold marking. UV lasering on stainless steel is the only rust-proof damage-free metal process. You can go half-way with a green laser, but a UV laser is a much better option. Only the cold marking process is a rust-proof and damage-free laser procedure, which resolves the rust problem on stainless steel. There’s no other way to prevent rusting from laser process on stainless steel. If you are laser processing stainless steel, you will need to use a UV laser or your stainless-steel cutlery will rust sooner or later depending on the exposure to salts, water, and chemicals, and your customers will notice. Kind Regards.