@Kathartes you want the steel to be homogeneous so to reduce as many impurities as possible but folding 1000 times is just going to work any steel you had back to iron due to decarborizing the steel, and folding is only necessary because the quality of Japanese metal is garbage due to poor smelting methods, like its literally an oversized bloomery furnace which is a very early smelting method. What folding does is it distributes to impurities evenly and squeezes them out since they have a lower melting point than the metal. They wouldn't need to fold in the first place if the steel they were starting with was of good quality like crucible steel.
what the hell, why is it that there is always some legendary sword or something that the mc fishes out of the really cheap pile at the blacksmith's shop?
@Jergens
Yeah, impurity is no longer a problem with modern metallurgy. But folding has other purpose: it creates multiple layers with different carbon content, to combine hardness and ductility in one blade (high carbon steel is brittle, while low carbon steel can't cut well). Also, it makes nice natural pattern without acid etching lol.
id like to chime in the metallurgy discussion @kathartes is basically right why they layer steel. not sure about the Japanese metal history. the best example i have seen on folded and layered steel is Men at Arms on youtube. layered steel is how lots of blades from cultures all over the world were made. for said reasons of brittle/strong and ductility/soft being opposite ends of the same scale so using 2 or more different kinds layered and folded so no come apart after heat and treat....well look it up for more details.
@inKraken@kathartes
Not sure what you're talking about. The only part of a blade that benefits from being hard is the edge, it's pointless for the rest of the blade to have hard steel. To combine a hard steel with a resilient steel you laminate it by forge-welding mild steel scales to a carbon steel core or a carbon steel edge to a mild steel core.
Folding modern steels is 100% aesthetic.
Also, I might have misinterpreted but there seems to be some minor confusion on the part of the katana. The katana was not folded in its entirety but rather laminated from pieces of folded steel. Minor point, I admit, but I felt it should be mentioned.