Controlling the Basal Texture for Significant Improvements in Mechanical Properties of AZ91D Mg Sheets Using Elevated-Temperature Constrained Groove Pressing

Abstract

A severe plastic deformation (SPD) technique, namely constrained groove pressing (CGP), is employed to investigate its influence on the texture and mechanical properties of AZ91D magnesium sheets. Three cycles of CGP were conducted on the AZ91D annealed sheets. Optical and scanning electron microscopy and X-ray diffraction (XRD) revealed that initially β-Mg₁₇Al₁₂ particles existed in the annealed sample. The grain structure of the workpiece was also refined from 18 µm to 14 µm after a single pass at 300 ˚C. There was a strong basal texture for the annealed sheet with maximum intensity of 3.4 multiple random distribution (MRD). After the first CGP cycle, the basal texture of the annealed sample was controlled and the maximum intensity of the basal texture did not significantly change. The inverse pole figures for various specimens demonstrated that the main texture was [0 0 0 1]║TD with increasing intensity during the next passes. It was found by measuring the hardness that 3-passed sample had the lowest homogeneity with a maximum inhomogeneity factor of 5.69. The yield strength and elongation of the annealed sheet were respectively increased to 166.7 MPa and 36.1%, showing about 29% and 47% enhancements, by performing just the first pass of the CGP operation.