When weber started making flavorizer bars out of porceloin coated steel no one realized that they would fail from micro cracks in the porceloin coating caused by differential expansion between the metal & the coating.
Many higher end grills now use SS for heat deflectors in gas grills but both weber & charbroil still use porceloin steel.
The heat deflectors in my Vermont castings were porceloin steel & burned out in three years!
My SS replacements are almost 5 & will outlive the grill & me!