Decreasing yield ratio of 70 GPa·% grade hot-rolled medium Mn steel by weakening multi-strengthening effects

Abstract The yield ratio of investigated steel decreased significantly from 0.93 to 0.59 by prolonging intercritical annealing duration to weak multi-strengthening effects. The contribution of each effect was qualified by theoretical calculation. The grain refinement strengthening and dislocation strengthening dominate the yield strength, while the reduction of precipitation strengthening and martensite strengthening mainly leads to the decrease of yield strength.