Microstructure Of Deformation And Recrystallization Of Nickel Single Crystal And Columnar Grain Crystal During Cold Drawing And Rolling

Deformation and annealing are important for controlling microstructures and improving mechanical properties of metallic materials. Research of the texture evolution of common polycrystal is very complicated due to the existence of defects such as grain boundaries with different orientation and dislocations. So it is helpful to simplify the research process and understand the deformation and recrystallization behaviors by the use of single crystal and columnar grain crystal.In this study single crystal and columnar crystal pure nickel (99.9%) were used to investigate the mechanical properties, microstructure and texture evolution during cold drawing, cold rolling and annealing by using hardness testing, scanning electron microscopy, and the electron backscatter diffraction (EBSD) technique.Columnar grain crystal with initial <001> fiber texture was used to study the texture evolution during cold drawing. It is found that initial <001> orientations change into <111> orientations gradually, and it also appears some <112> orientations with increasing reduction. <112> orientations can divided into two types: one is the transition orientation from <001> to <111>, the other is {111}<112> cyclic texture retaining in the sample.Single crystal with initial [001] direction and columnar grain crystal with initial <001> fiber texture were used to study the texture evolution during cold rolling and annealing. It is found that: 1) 98% cold rolled single crystal and columnar grain crystal have both different texture components from that of polycrystal. 2) After annealing for 2 hours at 800℃the cold rolled single crystal and columnar grain crystal of 98% reduction both turn into random orientations, instead of strong cube texture. 3) During annealing at 350℃the recrystallization occurs first in S-orientation deformation area of cold rolled single crystal which has lower stored energy, and the recrystallization mechanism of S-orientation deformation area is annealing twinning, hereby a new view is launched that crystallographical orientation is an important factor for controlling the recrystallization, and S-orientation is easier to occur recrystallization than Brass-orientation..