Study on Deformation Structure and Texture of Pure Zirconium with Large Grain Size Rolled at Liquid Nitrogen Temperature

The microstructure and the twinning behavior of the commercial pure zirconium with large grain sizes rolled uniformly at 77 K were studied. The deformation structures and the textures of samples with different rolling reductions were investigated by optical microscopy, scanning electron microscopy, electron backscattering diffraction (EBSD) and X-ray diffractometer. The EBSD results show that three types of twins, including C1{112}<11> compressive twins, T1{102}<10> and T2{111}<11> tensile twins, occur during the rolling and the C1{112}<11> compressive twins are the main twinning type. At the initial stage of the deformation, an amount of twins appear rapidly with only a few low-angle boundaries, indicating that twinning is favorable compared with dislocation slip. As the deformation reduction increases to 30%, however, a large number of low-angle boundaries are produced. It seems that the dislocation slip accommodated by twinning becomes the main deformation mechanism when the deformation reduction reaches approximately 30%. With the increase of the deformation no significant change on the texture type has been observed except slightly reduced intensity