Really? There is a large war going on right now and the key material is chips. Drone don't use a lot of steel, neither do missiles or modern airplanes.

Yes you need artillery and particularly shells. But you are so much more limited by the capacity of your munition factories that how much steel you have would not be an issue. One of the main things you would need for a new munitions factory is trained workers.

The World Wars were wars of mass mobilization and industrial capacity. People went into the first thinking cavalry was important, the second thinking battleships still mattered. My point is I have no idea what the next great war might be like, but thinking the winner will be who chugs out the most tanks in five years may be looking in the rear view mirror.