[unclebilly]

To answer a couple questions…

Carbon is not formed. It gets driven into the steel either from the coals in the hearth or from a yellow carburizing flame. The folding and hammer welding does create layers of high carbon and low carbon steel and if heat treated correctly, you can get a tough yet sharp blade that can hold an edge.

I doubt that these blades had great corrosion resistance. Nickel or chromium would be needed to get there.

Also one more misconception, hard steel does not have good corrosion resistance. It is the opposite, this is why knife materials like 22cv are unique. They give good corrosion resistance and hold an edge.