Influence of coiling temperature on microstructure and formability of cold rolling DC01 steel plate

By means of tensile test,metallographic examination and forming test,the effects of hot-rolled coiling temperature on microstructure and formability of cold-rolled DC01 steel plate were analyzed.The results showed that with the increase of coiling temperature from 680℃ to 730℃,the yield strength and tensile strength of cold-rolled DC01 steel plate showed a decreasing trend to varying degrees,the decreasing range was 20-30 MPa,the area shrinkage A₈₀ was increased about 2%,up to 41.5,and the plastic strain ratio r was increased about 0.4,up to 2.05,the work hardening index n did not change much.The comprehensive formability of cold-rolled DC01 steel plate was comparable to that of bell-type annealing DC01 steel plate.Under the condition of 730℃ high temperature coiling,the hot-rolled structure and cold-rolled structure of DC01 steel plate were both ferrite and a small amount of pearlite.The recrystallization resistance was small during cold rolling,which was conducive to the formation of γ fiber texture and made the plastic strain ratio increased greatly,thereby improving the stamping and forming properties of the material.Under the condition of 730℃ high temperature coiling,the relative cone value and bulging height of the cold-rolled DC01 steel plate were comparable to those of bell-type annealing DC01 steel plate,and the punching cup height of the cold-rolled DC01 steel plate reached 86% that of bell-type annealing DC01 steel plate,and the comprehensive form ability of the cold-rolled DC01 steel plate was good.