I watch a YouTube channel by Alec Steele where a lot of metal forging is done. From this I know that varying the carbon content in steel drastically alters the physical properties of the metal, as does different heating cycles (time for cooling and temperature of the forge). I am interested what is happening at the atomic structure during the forging process.
Here are some of my ideas on what is occurring. I think cooling time must affect the grain size of the steel microstructure. I have a vague idea that grain size affects material strength but I don't really know why. I also assume that the crystal structure varies with temperature. At a higher temperature, higher energy polymorphs are probably observed. I know adding carbon to the iron increases the strength of the material but again I don't know why. I assume there is some pi - d bonding occurring which may act akin to semiconductor doping, adding energy states for Fe electrons to populate, increasing metallic bonding?
This does not answer my question: What chemical characteristics give types of steel their properties? I am looking for an answer more focused on bonding and energy level population.