MECHANICAL PROPERTIES AND TEXTURE OF HOT EXTRUDED MAGNESIUM ALLOYS VIA RCP PROCESS IN USING COARSE RAW POWDER

摘要

Roll Compaction (RCP) process consisting of twin rolls, is available to assist the grain refinement and texture control of coarse magnesium alloy powders by applying severe strain hardening to them by all direction. Wrought magnesium alloys consolidated by hot extrusion in employing RCPed powder show a good balance of tensile strength and elongation. For example, in applying RCP process with 50 cycles to AZ31 alloy powder, the extruded wrought alloy reveals the extremely small grain less than 1～3μm, and superior mechanical properties of 380 Mpa TS, 310 Mpa YS and 15% elongation at room temperature. Grain growth could be also controlled due to the pinning effect by refined oxide dispersoids in the matrix after annealing at 673K for 3.6 ks. EBSP analysis results suggested that RCP process on AZ31 alloy powder accelerated not only grain refinement but texture control of the hot extruded AZ31 alloys. That is, the strong orientations of (0001) basal were obviously loosened with increasing the number of cycles in RCP on AZ31 alloy powder. The activation of basal and nonbasal slip caused the obstruction in decreasing the elongation of hot extruded AZ31B alloys with high yield strength via RCP process.