Engraving tool steel

[Stroonzo (Jeff)]

@OrturTech

Any diode laser, or Co2 for that matter will not be able to engrave metals.
They can mark them by chemistry as you already found but is not a enduring mark
A small use of a polish and it will be removed

Please have a look here to see a CO2 laser marking mild steel. I also polished it with Mr. Metal to illustrate clearly that the steel is physically marked.

Demonstration of Marking Steel with a CO2 Laser

Although it is possible, a fiber laser certainly is better. [Marking Steel with a CO2 Laser]