Procedural material with changeable damage and deterioration.
The material has multiple options allowing you to change the material roughness/weathering, scratches, dents and rust.
The material is available on my Patreon: https://www.patreon.com/Subbiani
The rust is based on ambient occlusion and may not work well when animated, but the material can be baked.
Video demonstration of the procedural material.