Short answers, pulled from the story.
Steel is defined by a precise carbon content between 0.02% and 2.14% by weight. This specific range allows the carbon atom to act as the gatekeeper of strength by locking the iron lattice into place. Without this precise balance, the material would not serve as the structural skeleton for modern civilization.
The earliest known production of steel dates back to 1800 BC in Anatolia. Artisans in Kaman-Kalehöyük forged ironware that would outlast the empires around them. This early production predates the industrial revolution by thousands of years.
Henry Bessemer, an Englishman, developed the Bessemer process in 1855. This method produces steel in large quantities cheaply by blowing air through molten pig iron to burn off excess carbon. The invention allowed mild steel to replace wrought iron for most purposes and sparked a new era of mass production.
China accounted for 54% of the world's steel output in 2023. More than 1.6 billion tons of steel are produced annually worldwide. This massive production makes the industry one of the most energy and greenhouse gas emission-intensive sectors, contributing 8% of global emissions.
The cooling rate dictates the final form of the steel by controlling how carbon precipitates out of the lattice. If cooled slowly, the carbon forms a layered structure called pearlite, while rapid quenching creates martensite, a highly strained and supersaturated form that is exceedingly hard but brittle. This transformation involves a change in volume that can cause a part to shatter if not tempered properly.