This paper demonstrates the effect of equal channel angular extrusion (ECAE) process on the microstructure and mechanical properties of cast magnesium alloy AZ91D. In terms of mechanical properties, the yield strength, ultimate strength, elongation rate, and elastic modula of AZ91D were increased from 86.3 MPa, 146.3 MPa, 1.84%, and 42.5 GPa to 144.1 MPa, 222.8 MPa, 15.15%, and 47.7 GPa after one ECAE pass, and to 109.1 MPa, 268.3 MPa, 25.48%, and 48.9 GPa after two ECAE passes at room temperature. In terms of microstructure, the dendritic crystal had been crushed because of sliding and rotation motion after the first pass of ECAE process, the crystal and black eutectic phase (Mg-17Al-12) of AZ91D has been elongated along the direction of extrusion. When the second pass was applied, the black eutectic phase began to remelt, and was reduced and distributed discontinuously. |