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Originally Posted by Razor
Mr. H, how about laminates? Say, as are used in traditional puukkos, with the outer layers soft to allow for a more flexible blade, but the inner layer (the one with the edge profiled on it) being harder to maintain its edge? How does one manufacture them without running into delamination challenges during use?
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Good question.
Laminated steels are among the oldest known existing artifacts of iron work ever found in the greater region we now call Syria. (IIRC, from Scientific American article, unkown date) . The oldest known smelted iron ore is said to come from the Sinai Peninsula found in and among ancient copper smelting sites and preceding all this is the near pre-historic use of found meteoric iron by ancient peoples to fashion into tools. This meteoric iron is distinguished by it's nickel content.
High carbon steel was very precious when hand smelting Iron because it either had to be very carefully sorted from the original cooled melt or forged in in a reducing fire of charcoal (source of carbon) to gain enough carbon from "carbon migration" while the steel was at heat. This was some very resource and labor intense work.
I also think that the technologies of making ceramic wares was the source of the technology to smelt the coppers, bronzes and then steels.
To use this hardenable carbon steel frugally, it was laminated or forge welded to another lower carbon steel body to make the entire tool.
The actual "weld" involves heating up both pieces of steel together to just under melting temperature and quickly hammering them together before they cool to the point of not sticking. Fluxes of glassy material are used to float the oxidized steel scale off the surfaces and get a good weld. Steel reacts very quickly with oxygen at high temps and this will prevent a clean strong weld.
When done well, the two types of steel become one piece and can take some very hard use without cracking because the softer outside iron supports the hardened high carbon core that makes up the edge.
The same principles apply to Japanese sword making as well as many carpenters and timber frame tools like old chisels and slicks that can still be found in second hand stores and occasionally estate sales.
Look for the two different colors of steel in the tool body.
If memory serves, we can still buy new laminated wood working tools from some sources, especially fine Japanese woodworking tools.
The traditional Puukkos are a good example of this being done well on a production basis. I think the Puukkos steel is roll forged together in the mill then manufactured into knives. They are famous for toughness.
We also have some custom makers of modern laminated steels that are doing amazing work. My friend
www.devinthomas.com comes to mind, he makes some exotic stuff in the high order stainless tool steels.