Why substitute steel for aluminum, when Aluminum Dibond is already lightweight and has high panel strength? Aluminum is not magnetic receptive, whereas Steel is magnetic receptive. A magnetic receptive surface adds a great deal flexibility in the event that you want to make temporary changes to your signage.
Although Steel weighs more than Aluminum, Steel Dibond has a higher panel strength than Aluminum Dibond due to its higher density.
Steel has a far higher panel strength than Aluminum. Steel is also magnetic, unlike Aluminum.