Microstructure and Mechanical Property of Pure Magnesium Processed by Cyclic Extrusion Compression

Abstract

Microstructure and tensile property of pure magnesium processed by cyclic extrusion-compression(CEC) at 350℃ for 2, 4 and 8 passes respectively, as well as for 2 passes at 250℃, 350℃ and450℃ respectively are investigated. Results showed that the microstructure of pure magnesium is significantly refined and recrystallized after CEC for 2 passes at 350℃. With the increase of passes, the grain sizes of CECed pure magnesium showed no obvious differences. It was found by means of electron backscatter diffraction(EBSD) analysis that a texture with the basal plane of grains inclining 20o-40o to the extrusion direction developed during the CEC processing. With the increase of CEC passes, the maximum intensity of the texture and Schmid factor of basal slip system increased. Compare to that for 2 passes,the yield stress of pure magnesium after CEC for 8 passes at 350℃ decreases from 60 MPa to 41 MPa,and the elongation increases from 8% to 16.7%. The yield stress and grain size of the pure Mg processed by CEC for 2 passes at 250℃, 350℃and 450℃ follows the Hall-Petch relationship, which can be described as σs= 5.4 + 338.6d-12.