Evolution of Grain Boundary Character Distribution in ECA-Pressed Pure Ti

초록

The evolution of the grain shape, texture and grain boundary character distribution (GBCD) of commercially pure titanium during equal channel angular (ECA) pressing was studied with the use of microscopy, X-ray diffraction and electron back scattered diffraction. The grain size refinement was about a factor of 100 although the high angle boundaries were only realized with more than 4 passes using the route Bc. The evolution of the texture during ECA pressing was derived from the complex, combined activation of slip systems and twin systems, and was confirmed by texture prediction modeling based on viscoplastic self-consistent theory. Grain growth phenomena were studied with a Monte-Carlo computer simulation technique using a direct mapping concept. Overall, the grain growth was characterized as a normal growth in the microstructure with stable random high angle boundaries. The texture and GBCD were found to be tenacious during the subsequent heat treatment after ECA pressing.