This effect was generated in Filter Forge, a Photoshop plugin that allows you to create your own filters.
I was looking for a way to make paint look like it was bubbling and stumbled across this really corroded looking setup. There are two presets, one with grey and one with a rust iron background.
The Depth Of Corrosion slider is the height control for the edges of the corrosion and at higher levels is shiny.
corroded cracks crack old rust rusty weathered
This filter has earned its author one of our rewards. They are given to the authors of popular filters and include a free copy of Filter Forge.