The Formation Mechanism Of Recrystallization Texture In SFG IF Steel

The modern cars are developing toward diversification, high-performance andhigh-grade direction.Auto industry has been the pillar industry of the nationaleconomy of developed country.Therefore the deep drawing steel has been developingwith the development of the auto industry. The auto industry also put forward higherrequirement of the quality and variety. It prompts the steel industry to continue toimprove process and increase performance to meet its demand. Therefore the fine-grain and high strength IF steel is widely used in the production.The research object is Nb fine-grain high-strength IF steel.It was processed atdifferent cold rolling rate and continuous annealing temperature.Use the OM, XRDand EBSD to observe the microstructure and texture of experimental steel at hotrolling, cold rolling and annealing process. The steel texture evolution and genetic lawof hot rolling, cold rolling and annealing is analyzed at different cold rolling reductionand annealing temperature. At last the recrystallization texture formation mechanismof Nb fine-grain high-strength IF steel is researched.Get the following mainconclusions:1. The hot rolling microstructure is axial and fully recrystallization.The graindistributes uniformly.When the cold rolling reduction is70%,75%and70%, the coldrolled microstructure presents plate strip structure and the deformation area graduallynarrows. Increasing the cold rolling reduction,the recrystallization ferrite grain tendsto decrease and recrystallization process is uniform gradually annealed at850℃.When the cold rolling reduction is80%and the annealing temperature is830℃,850℃and850℃respectively,the recrystallizied organization of the steel distributesuniform gradually, the change in grain size is not obvious.2. Different process has a significant effect on the texture of the steel. Orientationdistribution of the hot rolled texture is relatively scattered and the orientation densityis weak.The main texture is {554}<225>,{332}<258>,{112}<110> and {001}<110>texture.The cold rolling reduction is70%,75%80%respectively.With the cold rollingreduction increasing, the α-deformation texture gradually strengthens and forms apeak at {112}<110>. Annealed at850℃,the γ recrystallization texture is the maincomponent.With the increasing of cold rolling reduction, the γ recrystallizationtexture gradually strengthens and forms a peak at {111}<112>.When the cold rollingreduction is80%, the experimental steel has the strongest γ texture.When the coldrolling reduction is80%and the annealing temperature is830℃,850℃and850℃respectively, the recrystallization texture of experimental steel enhances at first andthe steel obtain the optimal γ recrystallization texture at850℃.3. Hot rolled-cold rolled-annealing process have a transformation and geneticbetween the texture. The cold rolled texture mainly inherited the {001}<110> texturein hot rolling.Main texture of the cold rolled steel is {111}<110>,{111}<112>,{112}<110> and {001}<110> texture. The different orientation texture volumecontent is:{111}<112>>{111}<110>>{112}<110>>{001}<100>.The strength of αdeformation texture is greater than the γ texture.The annealed γ recrystallization texture in experimental steel significantly enhances and forms a peak at {111}<112>.The recrystallization texture inherits the major component of deformation texture andits strength gradually increased.4. Realize the control of recrystallization texture by changing the cold rolleddeformation storage energy and nucleation position of different orientation grain inthe cold rolling process. Realize the control of recrystallization texture by changingthe grain boundary migration velocity and distribution of CSL in the annealingprocess.The main formation mechanism of recrystallization texture is orientednucleation and the selecting growth.