This article focuses on the mechanisms, models, prevention, correction, and effects associated with decarburization inherited from semi-finished product processing prior to induction heating. It discusses the diffusion of carbon in austenitic iron, which has a face-centered cubic crystal structure that provides an interstitial path for the migration of the relatively small carbon atoms. The article describes the evolution of steel microstructure with progressive decarburization (in air) to a steady-state carbon gradient using an iron-iron carbide phase diagram. It provides useful information on the impact of alloying on vulnerability to decarburization, and the impact of decarburization on the mechanical properties of steels and cast irons. The article also describes the technological operations that potentially cause decarburization and the practical implications for induction hardening.