Among them, the medium Mn steels receive increasing attention due to their excellent mechanical properties and relatively low alloying cost.

Many advanced high strength steels (AHSS), including light weight steels, quenching and partitioning (Q&P) steels, high Mn twinning induced plasticity (TWIP) steels and medium Mn transformation induced plasticity (TRIP) steels, have been studied to meet the demands for the lightweight and affordable automobile, ,, , ]. This demonstrates that the mechanical combination of non-V-alloyed medium Mn steel can be improved to an equivalent level of 0.7% V alloyed 10 Mn steel just via the economic strain-induced cementite precipitation. The warm rolling at 600вЊ with 63% thickness reduction can produce the steel with the best mechanical combination of 1.2 GPa UTS and 35% TE, due to the formation of many ultrafine austenite grains and strain-induced cementite precipitates. The further increase of rolling temperature to 700-800вЊ causes a considerable amount of pearlite to be formed during the IA, and then martensite is formed after the IA, resulting in dramatical increases in both YS and UTS but at the great loss of ductility. However, the size of relatively coarse recrystallized austenite grains and the resultant yield strength (YS) remain almost constant in this temperature range. As a result, both ultimate tensile strength (UTS) and total elongation (TE) increase. The increase of warm rolling temperature from 250вЊ to 600вЊ leads to enhanced recrystallization in martensite during the intercritical annealing (IA) at 620вЊ for 5 h. Strength appeared to increase with the rolling temperature but strengthening mechanisms varied. The influence of warm rolling processes on the microstructures and tensile properties of 10 Mn steel was studied.

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