Not steel, but I was impressed to learn about the physics of obsidian knives produced during the Mayan civilization:
> When skillfully worked, the edges of prismatic blade made from obsidian can reach the molecular level, i.e., the material has a cutting edge that is only one molecule thick.
> [Glass knives] were once the blade of choice for the ultra-thin sectioning required in transmission electron microscopy because they can be manufactured by hand.
> ..Some labs still use glass knives because they are significantly less expensive than diamond knives. A common practice is to use a glass knife to cut the block which contains the sample to near the location of the specimen to be examined.
> Then the glass knife is replaced by a diamond blade for the actual ultrathin sectioning. This extends the life of the diamond blade which is used only when its superior performance is critical.
> Obsidian, a naturally occurring volcanic glass, can also be used to make sharp glass knives; obsidian surgical scalpels are available commercially.
I have family in pathology. Labs do a lot of sample sectioning before microscopy. Thin enough to stain and visualize internal structures (think onion skin).
> When skillfully worked, the edges of prismatic blade made from obsidian can reach the molecular level, i.e., the material has a cutting edge that is only one molecule thick.
https://en.wikipedia.org/wiki/Obsidian_use_in_Mesoamerica#ci...