Effect of processing route on grain refinement in pure copper processed by equal channel angular extrusion
(1. School of Electro-Mechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China;
2. Guangdong Institute of Special Equipment Inspection and Research, Zhongshan 528400, China;
3. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
4. Key Laboratory of Nonferrous Metal Materials Science and Engineering,
Ministry of Education, Central South University, Changsha 410083, China)
2. Guangdong Institute of Special Equipment Inspection and Research, Zhongshan 528400, China;
3. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
4. Key Laboratory of Nonferrous Metal Materials Science and Engineering,
Ministry of Education, Central South University, Changsha 410083, China)
Abstract: An experimental study of the microstructures in pure copper billets processed by 8 passes of equal channel angular extrusion (ECAE) via an extended range of processing routes with a 90° die is carried out. Each processing route is defined according to the inter-pass billet rotation angle (χ), which varies from 0° to 180°. According to the generation of high-angle boundaries and reduction of grain size by electron backscatter diffraction (EBSD) measurements, the grain refinement is found to be most efficient for route with χ=90° and least efficient with χ=180°, among the seven routes studied. This trend is supported by supplementary transmission electron microscopy (TEM) measurements. Comparison of the EBSD and TEM data reveals the importance of considering the non-equiaxity of grain structures in quantitative assessment of microstructural differences in ECAE-processed materials.
Key words: pure copper; equal channel angular extrusion; severe plastic deformation; strain path; grain refinement