Study on Pack Rolling and Annealing Process for Ultra-Fined Grain Austenite Stainless Steel

In this study, ultra-fined grain austenite stainless steel was obtained by pack rolling and subsequent annealing. The microstructure and defect were analyzed by using scanning electronic microscopy (SEM) and X-ray diffraction (XRD), etc. Thus the influence of the rolling reduction, the annealing temperature and the annealing time on the microstructure of 304 austenite stainless steel was accomplished. The results indicate that with the pack rolling reduction increased, the grains were elongated more obviously along the rolling direction. There were numerous dislocations and twinning within the grains. Moreover, there is amount of strain induced martensite with the rolling. The grains were remarkable refined after annealing, in which the microstructure was reversed and recrystallized, and the strain induced the martensite transferred to austenite. The average grain size decreased to 0.5μm with the sample of the 75% rolling reduction after annealing at 800°C for 30 minutes. In addition, the mechanism of the pack rolling on the grain size reduction was analyzed.