The steel industry on its own is responsible for an estimated 11% of the total CO2 emissions worldwide showing the need for increased recycling. But plain circular economy leads to an accumulation of unwanted impurities which increases the scatter in microstructure formation and deteriorates material properties being the root-cause of downcycling. While available models for process design interpolate within known parameter spaces, they fail at extrapolative modelling and do not consider impurities. Yet, extrapolative models are needed to allow for high recycling rates also in microstructure-sensitive high-performance alloys.

A key to understanding and modelling microstructures is grain boundary and interface segregation as this may control kinetics of microstructure evolution. This talk will present first of all segregation data for all relevant solutes and tramp elements in steel production for ferritic and austenitic steels. The second part of the talk focuses on how segregation data can couple to microstructure evolution highlighting examples from static recrystallization to phase transformation for realistic steel compositions.