Tension/compression anisotropy in hot forged Mg-Al-Ca-RE alloy

Abstract

Die-cast Mg-Al-Ca-RE (RE = rare earth) alloy was upset forged by compression at 573 K with the true strain rate of 0.1 s-1 for grain refinement, and the tension/compression anisotropy at room temperature was examined. Before the hot forging, the die-cast alloy had random texture and yield stresses in tension and compression were similar. However, the forged and fine-grained specimens had (0001) texture inclined by 0-20° to the forging plane, which caused tension/compression yield stress ratio of 1.4 when the specimens were deformed perpendicular to hot forging direction. Grain coarsening by annealing of the forged specimen enhanced the ratio to 1.9 because more c-axis expansion twins formed at the early stage of the compression. Thus, grain refinement is necessary for reducing tension/compression anisotropy in hot-forged Mg alloy parts. ©2009 The Thermoelectrics Society of Japan.