You're looking at a very very large fiber / YAG laser to cut it. A low power YAG laser can engrave steel - commercially these start at about $30k
https://www.coherent.com/Applications/index.cfm?fuseaction=f...
https://vimeo.com/106264555
But it's true that sub-100W CO2 lasers are not even remotely capable of cutting steel.
You're looking at a very very large fiber / YAG laser to cut it. A low power YAG laser can engrave steel - commercially these start at about $30k