Recent Trends in Producing Ultrafine Steels

Ultrafine grained steels with grain sizes below about 1 µm offer the prospect of high strength and high toughness with traditional steel compositions. These materials are currently the subject of extensive research efforts worldwide. Alloy design is one of the first considered issues, while designing new steel with targeted mechanical properties. However, the alloying content of steel does not fully determine the mechanical properties, but manufacturing procedure, hot rolling and cooling parameters, heat treatment parameters etc. are also of vital importance. For instance, same steel with different processing conditions can exhibit rather large variations in properties. To be precise, chemical composition with the processing parameters determines the microstructure, which in turn determines the properties of the steel.