Hi and thank you! Well this is the general view of my material nodes
First I added color varriation using noise texture to mask between two colors. Then for the scratches, this tutorial help me a lot: https://www.youtube.com/watch?v=e4BhdrFDHkQ&ab_channel=Bandyte
This is my nodegroup of the scratches. The tutorial explains how to create it.
Then I use pointiness wich is on geometry node, to highlight the edges
These are the nodes of my general dirt, but I use it very subtle
Then I added more darker dirt on occluded areas using the ambient occlusion node
And a little extra of ambient occlusion to get the look that I wanted.
Finally I put some little imperfections connected to the bump node
I hope this helps a little.