Small quantities of iron were smelted in ancient times, in the solid state, by heating the ore in a charcoal fire and then welding the clumps together with a hammer and in the process squeezing out the impurities.With care, the carbon content could be controlled by moving it around in the fire.These qualities include such things as the hardness, quenching behavior, need for annealing, tempering behavior, yield strength, and tensile strength of the resulting steel.
Plain carbon-iron alloys with a higher than 2.1% carbon content are known as cast iron.
Basically, steel is an iron-carbon alloy that does not undergo eutectic reaction.
In contrast, cast iron does undergo eutectic reaction.
This was followed by the Siemens-Martin process and then the Gilchrist-Thomas process that refined the quality of steel.
With their introductions, mild steel replaced wrought iron.With modern steelmaking techniques such as powder metal forming, it is possible to make very high-carbon (and other alloy material) steels, but such are not common.