The Study For The Effect Of Recrystallization Annealing On Structure And Texture Of IF Steel

The deep-drawing sheet is the important raw material in automobile industry, recrystallization annealing is the critical production process of automobile sheet. Therefore, It has great theoretical and pratical meaning for studying the microstructure and texture evolution of automobile sheet during recrystallizing.This paper selected Ti+Nb-IF and Ti+Nb+P-IF steel as raw material, taked the cold-rolled reduction and annealing temperature as the impacting factor.Reseach the relationship between microstructure and property of Ti+Nb-IF and Ti+Nb+P-IF steel by microstructure observation,TEM analysis, texture measurement and mechanics property test. The result of the experiment indicate:(1) Adjusting the cold-rolled reduction of Ti+Nb-IF could effectively control its tensile strength and r value; Adjusting the annealing temperature of Ti+Nb-IF could effectively control its elongation and yield strength.①When reduction is 84%, elongation and yield strength. could effectively controled by annealing process;(2) When reduction is 80 %, strength index and plastic index could effectively controled by annealing process;(3) When reduction is 75%, tensile strength,yield strength and r value could effectively controled by annealing process.(2) The recrystallization texture evolution of Ti+Nb-IF:When annealing temperature are 680℃and 700℃, the strength ofγfiber texture decreases as the cold rolled reduction change from 80% to 84% to 75%; When annealing temperature is 720℃,αfiber textures of three kinds of reductions are all weak, the strength ofγfiber texture strengthen with the increasing of the cold-rolled reduction; When annealing temperature is 740℃, the strength ofγfiber texture all weaken in the three kinds of reduction.(3) After hot rolling in anstenite region, the cold-rolled reduction of Ti+Nb+P-IF steel was 70%,the change of grain size of annealed samples was not great,between 20μm and 30μm; After hot rolling in ferrite region, the grain size of annealing samples has the minimum value(20μm).(4) After hot rolling in ferrite region, the substructure of cold deformation and recrystallization of Ti+Nb+P-IF steel with 70% cold-rolled ruduction resembled the substructure of cold deformation and recrystallization in 90% cold-rolled ruduction after hot rolling in anstenite region.(5) The same reduction, hot rolled in ferrite region, the second phase particles of annealed samples of Ti+Nb+P-IF steel were bigger than that of annealed samples in hot rolled austenite region.(6) When the cold reduction was 85%, the Ti+Nb+P-IF steel hot-rolled in austenite region could obtain the strongest cold-rolled and annealedγfiber texture, but the Ti+Nb+P-IF steel hot-rolled in ferrite region could not obtain strong cold-rolled and annealedγfiber texture.