>>8985
>There could be difference between ore and ore but after they're transformed into iron bars how can anyone say that there's a difference between the Fe atoms forming those bars? Two Fe atoms cannot be different else one of them wouldn't be Fe. So a bunch of Fe atoms cannot be different from another bunch of Fe atoms. There could be difference in coal quantity but to making steel one should add more C into the mix anyway.
Hardly even close to the actual reality of metallurgy.
There are two important issues: 1) iron ore often contains other metals (chromium, vanadium, etc) which cannot easily be distilled away in the refining process (even in binary mixtures result would be an eutectic mixture, not pure Fe), and secondly, carbon itself forms an alloy with iron, again making the whole system much more complicated.
Also, iron undergoes several phase transitions when cooling down from melt to room temperature. At each phase transition there is an abrupt change in mechanical properties of the metal; it is what leads to tension present in final product. By finetuning composition, one can change temperatures at which those phase transitions occur, or even access hidden phases that aren't possible with pure iron or binary steel.
In any case, I'd assume swords gradually got more curved with time; that there was no phase transition from straight to curved blade. At first, they'd work hard to try to make it straight; later on, slightly curved became the norm and nobody worried about curvature anymore since it isn't too bad.