Microalloying and austenite evolution during hot working in near net shape processed steels

This paper reviews some of the main metallurgical singularities that characterise near net shape casting technologies, with special emphasis on the role that microalloying elements play in the different austenite conditioning mechanisms operating during rolling. To begin with the different mechanisms used for the refinement of the as cast austenite in direct charging processes are considered. The effect of Nb on the retardation of recrystallisation as solute drag or strain induced precipitated is analysed in depth. Special attention is paid to Ti microalloying and the interaction of TiN precipitates formed during solidification, and rolling with softening mechanisms is discussed. The second part of the paper deals with the conditioning of the austenite microstructure in terms of strain accumulation and contains a thorough analysis of how the different microalloying elements, including Mo, can help in this.