Effect of annealing process and w(Cr) on microstructure and properties of 500 MPa cold rolled dual phase steel

Based on the production process of cold-rolled DP steel,the mechanical properties of experimental steel were tested through the tensile experiment after annealing by the ULAVC-CCT-AY-II continuous annealing simulator.and the microstructure was observed by the metallographic microscope OLYMPUS-BX51 and SEM.The results showed that: F+M could be obtained through holding temperature between 760-780 ℃ and setting cooling temperature at 670 ℃;Hardenability of austenitic would be improved by the addition of Cr.The morphology and distribution of Martensite was changed by the preliminary recrystallization and the well-distributed microstructure of F+M could be obtained.