Mg₉₆Zn₂Y₂合金インゴットおよびチップの押出における強化メカニズム

抄録

In order to make the effect of processing clear, Mg₉₆Zn₂Y₂ alloy ingot and machined chips were extruded at various extrusion conditions. Tensile yield strength of extruded bar from ingot and extrusion force were increased with decreasing extrusion temperature. Tensile yield strength and extrusion force was proportional to hardness of ingot that is measured at extrusion temperature. Increased hot hardness resulted in improved strength with increasing of the degree of work hardening and extrusion force. Improvement of the degree of work hardens was observed as crystal orientation by XRD. Meanwhile, strain hardening of machined chips plays a major role of strengthening at extruded bar from chips. Static recrystallization of chips at preheating causes randomization of crystal orientation and higher elongation of extruded bar from chips. Difference in recrystallization behavior between extrusion of ingot and chips, dynamic recrystallization at ingot extrusion and static recrystallization at chips extrusion, was due to difference of strength mechanism of extruded bar from ingot and chips.