A medium-Mn steel processed by novel twin-roll strip casting route

A medium-Mn steel (Fe-0.3C-4Mn-1.82Al-0.6Si wt-%) was produced by a novel processing route involving twin-roll strip casting, hot rolling and intercritical annealing (IA). Macrosegregation was absent in the as-cast strip. The microstructure of the as-cast strip consisted of martensite and austenite (similar to 10 vol.-%), and the solidification structure was characterised by dendritic structure. With an increase in IA temperature from 680 to 725 and to 755 degrees C, austenite fraction in intercritically annealed steels was increased from 22 to 45% and then decreased to 27%. The 710 degrees C intercritically annealed steel yielded excellent mechanical properties with a tensile strength of similar to 1007 MPa and total elongation of similar to 48%, achieved by a high volume fraction of austenite (similar to 42%) with appropriate mechanical stability.