Most clad metals are composites of a cladding metal including stainless steel, nickel and nickel alloys, and copper and copper alloys welded to the backing materials of either carbon or alloy steel. The two metals are welded with each other at a mill in the roll underneath heat and tension. https://www.dostally.com/post/306123_metal-clad-walls-provide-durability-weather-resistance-and-modern-aesthetics-com.html