Here is my Diamond Plate PBR material made in Substance Designer. The Substance Designer graph source file (.sbs) is available in Gumroad at: http://gum.co/diamond_plate_sbs
The mud, scratches and damage are adjustable parameters and are exposed by default. By tweaking the graph it's easy to expose other parameters too.

The Diamond Plate substance graph (.sbs) is available in Gumroad at http://gum.co/diamond_plate_sbs