Microstructure and Property of Vanadium Micro-alloyed Cold Rolling Dual Phase Steel

The effect of coiling temperature after hot rolling and annealing temperature on the microstructure and properties of vanadium micro-alloy cold-rolled dual phase steels was studied in laboratory.Microstructure and property were compared between the as-hot rolled and after annealing strip,strength mechanism of microstructure with dual phase was also analyzed.The results showed that the best mechanical properties is obtained when the hot rolling uses a final rolling temperature of 900 ℃,a coiling temperature of 650 ℃,and continuous annealing uses an annealing temperature of 800 ℃ and an overaging temperature of 270 ℃.The results are as follows:the yield strength of the steel is 437 MPa,tensile strength is 815 MPa,elongation is 21.0%,n value is 0.191 2.The mean grain size of annealed sample is 11.5 grade,volume fraction of martensite is about 38%.Explore the influence of hot rolling and continue annealing process on the microstructure and properties,the production process were optimized.