Study On Rolling And Annealing Processes Of IF Steel With V-Ti Microalloyed

Interstitial-free steel has become an important part of modern automotive steel because of its excellent deep-drawing property.However,IF steel currently studied is mainly containing titanium and niobium elements.Its research work on vanadium-containing IF steel has been less developed.Based on this,this paper designed the vanadium-containing IF steel components,starting from the hot rolling process,and then the cold rolling and annealing process was studied to find the relationship between process system and the final mechanical properties,and finally explore the recrystallization formation process,To further reduce costs and optimize the product structure to provide a theoretical basis.The main results are as following:(1)When hot rolled in the all-ferrite zone of the experimental steel,the recrystallization texture of the cold-rolled annealed sheets is strong {115}<491>and{112}<351>with low strength and elongation and an r value of only 1.29.On the other hand,the hot rolling in the austenite region significantly weakened the ?*recrystallization texture,enhanced the y texture component,and improved the mechanical properties.The r value increased to 2.13.(2)When the cold rolling reduction rate increased from 60%to 87.5%,y recrystallization texture gradually increased.The tensile strength of the annealed sheet gradually increased and the elongation decreased,r increased from 1.05 to 2.35.In addition,a suitable two-stage cold-rolling process can further improve the y recrystallization texture and increase the r value of the annealed sheet.(3)When the cold-rolled sheet is annealed at 700-800?,as the annealing temperature increases,the tensile strength gradually decreases and the deep-drawing property gradually increases.Compared with the batch annealing,continuous annealing can increase the tensile strength of the annealed sheet,while enhancing y recrystallization texture,significantly increased r value of up to 3.24.(4)In the early stage of recrystallization of cold-rolled microstructure,the grains preferentially nucleate at the grain boundary of the cold-deformed matrix,and the nucleation of {111}<uvw>-oriented grains dominates.With the development of recrystallization,y cold-rolled deformation of the matrix was first annexed,and?-deformed tissue recrystallization slower.In subsequent growth,{111}<uvw>evolved into a predominantly recrystallized texture by virtue of size and quantity.