Research on the Precipitates in Warm-Rolled Ti-Bearing Interstitial-Free Steel Sheets

Abstract

Warm-rolling can save the production cost and extend the production kind of hot-rolled IF steel strip, the precipitates strongly influence the annealing process and texture evolution so as to the final mechanical properties of the production, very few studies has relate to the precipitates of IF steels warm-rolled in ferrite region. In present work, two Ti- IF steels were warm-rolled in ferrite region under different rolling parameters and the precipitates were investigated. Transmission electron microscopy (TEM) and Energy dispersion Spectroscopy (EDS) microanalysis were carried out on carbon extraction replicas, the characteristics such as morphology, type, amount and size of precipitates were analyzed. The results show that different type of precipitates were appeared in two steels, TiN, TiS, Ti4C2S2 and TiC were found in common Ti-IF steel, but in high strength Ti-IF steel, the amount of TiS, Ti4C2S2 was very few and FeTiP precipitates appeared, the type and morphology of precipitates were not affected by rolling parameters, however, the number and size of precipitates were changed. Finally, the effect of different P content on the change of precipitates was analyzed, the precipitating mechanism was also discussed.