High strength steels include between about 20 and 80 volume percent of ferrite and between 20 and 80% of austenite during interstitial annealing, wherein the calculated Ms temperature for the austenite phase during intercritical annealing is 100 ° C. The high strength steel exhibits a tensile elongation of at least 20% and a maximum tensile strength of at least 880 MPa. The high strength steel may contain 0.20 to 0.30 wt% of C, and 3.0 to 5.0 wt% of Mn by adding Al and Si so that the optimum critical temperature is 700 캜 or higher.
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