Effect of Annealing Treatments on the Microstructure and Texture Development in API 5L X60 Microalloyed Pipeline Steel

Effect of annealing treatments at 600, 800, 1000 and 1200 °C on the microstructure, texture, grain boundary characteristic and recrystallization fraction of Nb-microalloyed X60 steel is evaluated by using x-ray diffraction and EBSD techniques. The results indicate that bimodal as-received microstructure is changed to a homogeneous equiaxed grain structure above annealing at 1000 °C. Macro-texture investigations depict that increasing annealing temperature results in considerable variation of texture intensity, especially at 1200 °C. Maximum intensity corresponds to {001}〈310〉, Goss, copper texture components as well as near γ-fiber at 1200 °C. Recrystallization analysis shows that volume fraction of recrystallization noticeably is increased by annealing temperature at 1200 °C. Recrystallized grains are mainly oriented along γ-fiber, especially close to {111}〈112〉 texture component. Moreover, coincidence site lattice (CSL) analysis shows that the effect of annealing temperature on the volume fraction of Σ3 boundary is negligible.