Effect of Cr and Annealing Process on Microstructure and Properties of 600 MPa Grade CSi Mn System Cold Rolling Dual-phase Steel

The 600 MPa C-Mn system cold rolling dual-phase steel was prepared taking the advantage of Multipas multifunction continuous annealing simulator in laboratory, then the microstructure morphology and properties feature were researched about the dual-phase steel which contains Cr or not under different annealing temperature, and the phase-transition temperature was detected using differential thermal analyzer. The results show that the yield strength, tensile strength and yield ratio for the steel without Cr increase with the increase of annealing temperature, but for the dual-phase steel containing Cr at800 ℃ annealing temperature, there is a obvious low peak of yield strength and yield ratio. At the same time, with the adding of Cr, two-phase temperature region becomes narrower, the A3 temperature point becomes lower, the solution temperature of the carbide becomes higher, banded structure is improved obviously, and the size of martensitic becomes smaller and more uniform.