Effect Of Ti-IF Steel Precipitates On Microstructure And Deep Drawability

In this paper,I researched the factory production of Ti-IF steel. The main purpose was to research how the different billet reheating temperature, coiling temperature, annealing temperature, the temper rolling and tensile test affected the final microstructure and drawability of Ti-IF steel. The main way was through laboratory simulation of reheating for billet and the actual production of coiling temperature, annealing temperature and the temper rolling of experimental, by SEM and Nanoindentation, analyzed of size distribution of precipitates of Ti-IF steel of different stages, and researched effect of Ti-IF steel precipitates on microstructure and deep drawability.The effect of different reheating processes on precipitates of billet of Ti-IF steel showed. With the improvement of the coiling temperature, the grain size variation of no obvious pattern, which was then considered to have the plastic sheet in favor of the hot rolling. By SEM, Ti-IF steel billet dissolved precipitates occur at different reheatisng temperatures, meanwhile, decrease in the number and the size becomes smaller. When the reheating temperature at and above 1150 ℃, the precipitates in the number of different positions and the dimensional of Ti-IF steel billet was changed small, and the effect of precipitates was weakening, and the TiS into larger size Ti4C2S2, these have advantages to reduction of fine precipitates precipitated and conducive drawability.The effect of different coiling temperatures on the microstructure and precipitates of hot-rolled Ti-IF steel showed. With the coiling temperature increased, grain size variation of no rules. In comparison, the use of the coiling temperature at 730 ℃ outside to the inside of the ferrite grains to improve the uniformity, it was advantageous for the subsequent cold rolling. With the coiling temperature increased, the amount of precipitated and the size increased, and the only increased was TiC precipitates. The high coiling temperature conducives to TiC precipitates gathering grew and form coarse precipitates, it has advantages to TiC precipitates gathering grew and TiC particle precipitation continues in the subsequent cooling process.The effect of different annealing temperatures on microstructure and precipitates of deep drawing Ti-IF steel showed. cold-rolled Ti-IF steel sheet grains’ size became larger and the grains gradually equiaxed. Compared with coiling at 730 ℃ after the hot rolled, the type of precipitates had no change, but the number reduced, it was because TiS and TiN precipitates was broken under the cold rolling, and TiC precipitates gathered grew, so the size was become lager, it has advantages to form deep drawing texture.The effect of the different temper rolling of Ti-IF hot galvanized sheet on microstructure and properties showed. The hardness increased of the surface of different samples through the temper rolling because of grain refinemented. Temper rolling is more obvious influence on the yield strength, and there was a certain effect on the elongation, but did not influence the tensile strength. With the hardness increases of the material, deformation resistance and yield strength increases, eventually the deep drawability will be affected adversely. So choose a relatively low temper rolling is beneficial to deep drawability.