Most clad metals are composites of a cladding metal such as stainless steel, nickel and nickel alloys, and copper and copper alloys welded into a backing product of both carbon or alloy steel. The two metals are welded together in a mill inside of a roll under warmth and tension. https://www.jointcorners.com/post/316163_metal-weatherboard-siding-offers-durability-and-a-modern-aesthetic-commonly-used.html