If it is, go find it as no one else can. All the people who made it, who joined the plates are dead, and the mills are gone; the equipment to make the plate, sold for scrap decades ago.
Like I said this is just a folly and not worth the effort or the time, when the time and resources are better used to make AI controlled surface and sub-surface drones - something the Navy is attempting, but instead of making cheap drones that can operate in swarms, they seem to be focusing on making a few big expensive drones.
Which is why we are not prepared for modern warfare - they focus on making big, expensive, low volume weapons, which when destroyed and used up, leave the cupboard bare.
Quantity has a quality all its own.
As for making thin-skinned vessels, even the Navy sees that as a dead end. The future is submarines and cheap AI drones.
Well, Bob, the only really elusive bit of metallurgy I am aware of is the legendary Damascus steel of the Middle ages. Efforts to recreate its legendary properties have been ongoing for decades. But, like the armor steels, there is a combination of chemical composition, tempering and work that make the metal what it is. Crystal size, orientation, dispersion are all related to mechanical processing and thermal treatment.
To find it you might have to dig through actual print materials not just do a mouse click. But even then, there is a lot of ongoing research being done on the properties of steel, much of it by bladesmiths, that might be adapted to larger projects; there is considerable interest in up-armoring vehicles, not just for military applications, and more modern developments are factored in with layered armor and anti-spall blankets for military and personal use.
If a web search can find this:
https://www.dst.defence.gov.au/sites/default/files/publications/documents/DST-Group-TR-3305_0.pdfThen it is likely the 'formulas' still exist for those armored belts, or with the actual ships, they could be sampled and reverse engineered.
As for mills, they would have to be built from scratch, most likely, and the people running them would be pushing buttons rather than pulling levers, not using 80 year old technology to produce the modern result.
Observing the use of shaped charges (RPG warheads) dropped from drones (or attached to them) in Ukraine, the question is of how to effectively armor against attacks using more modern warheads.
Because no matter how many drones you have, you have to deploy them from somewhere. The Chinese have islands they have augmented or flat-out built throughout the Spratleys which give them forward basing options. Their container ship fleet gives them mobile options, along with deniability right up to the time they start launching. Hostilities toward ostensibly merchant vessels short of open warfare will be frowned upon, and the load out on any (if not all) such vessels could have a military component sitting idle until called up. We don't have enough submarines to shadow them all.
I agree that drones will be (are) 'the next big thing' in warfare, and we have a ways to go to get up to speed. But having drones is only part of the equation; we have to get them to where they can be utilized effectively. If we are to effectively deploy even one-way drones with loiter time over target areas, we need a platform to deploy them
from, in effective numbers, and if it isn't survivable, the drones will not matter.
We also need the sort of defense that will counter the enemy's drones, whatever form that takes.