40 various metal textures I've made over time.
They are PBR-friendly, 1024x1024, TGA format.
For each, you have:
diffuse/albedo (w/ alpha) + normal + mask (rgba) + emissive (for 4 of them)
-R : Metalness
-G : Roughness
-B : Ambient Occlusion
-A : Height
This asset can also be found on my Unity's assetstore and UE4's Marketplace.