Burnt Metal Material

[St_17]

Hello, since I am a newbie I am looking for a solution For my problem

I try to achieve a burnt effect, as show in the picture below. I have tried it with the AO Map, but I can only use one color without a gradient, what would be the correct way to create such a material?

[Mvskokvl]

Heating from welding causes metals to oxidize, which consequently creates a layer of thin film.

Make Legacy Metal and apply it as texture.

Note: Different coloration means different thickness, some variation and specific IOR…
eg.

PS
Use Distance map & Curvature to your advantage.