The Effect of Fabrication Process on Microstructure Evolution of N18 Alloy Sheets

The microstructure and texture evolution of N18 sheets are studied after a series of fabrication processes which contain hot rolling at 780°C, cold rolling with the total deformation of 10% and recrystallized annealing at 580°C for 1.5h. The results show that grain size and the density of low angle grain boundaries of the fabricated sheets increase with the increase of hot rolling pass, and there is a little difference of grains for cold rolling and recrystallized sheets that deformed grain could be observed on both of them, which indicates that dynamic recrystallization occurs during hot rolling, but the cold deformation was so limited that the sheets could not be fully recrystallized because of lack of recrystallization driving force. Second phase precipitated particles (SPPs) in as-received N18 sheets are smaller than that in the fabricated sheets. It may because that part of SPPs are dissolved during hot rolling which lead to the volume decrease and supersaturation elements separate out to form SPPs again or primary SPPs grow up during recrystallization which lead to volume extending. The N18 sheets mainly have (0001) texture before and after fabrication and the density of basal pole which was along normal orientation on rolling plane increases as rolling pass increasing but decreases after cold rolling and increase again after recrystallization. After fabrication, the value of f_ND increases for N18 sheets, but there were a little difference among different rolling pass. EBSD analysis shows that the grains of rolling sheets mainly display orientations with <10 1¯ 0>//RD and {0001} <10 1¯ 0> texture was stronger, and the grains of recrystallized sheets mainly display orientations with <11 2¯ 0>//RD made {0001} <11 2¯ 0> texture increasing.