CAJ | 학술논문

利用往复挤压在300~360℃细化铸态Mg-6Zn-1Y-1Ce合金组织，研究其组织演变和挤压参数对再结晶组织的影响。结果表明：往复挤压合金横截面边缘存在不均匀环，由靠近筒壁的细晶环和粗晶环组成，其宽度随着挤压温度提高而减小；细晶环是由边缘区域与挤压筒壁摩擦而发生第二轮再结晶所致，粗晶环是由再结晶晶粒长大所致；合金晶粒度由变形速率和温度决定，经340℃挤压合金晶粒最细，平均粒径8.2μm。除边缘外，往复挤压过程中合金在挤压阶段发生一次再结晶，墩粗过程和后续多道次挤压变形都是通过晶界滑移实现。因此，随着挤压道次的增加，保温时间随之延长，晶粒随之被粗化。
이용왕복제압재300~360℃세화주태Mg-6Zn-1Y-1Ce합금조직，연구기조직연변화제압삼수대재결정조직적영향。결과표명：왕복제압합금횡절면변연존재불균균배，유고근통벽적세정배화조정배조성，기관도수착제압온도제고이감소；세정배시유변연구역여제압통벽마찰이발생제이륜재결정소치，조정배시유재결정정립장대소치；합금정립도유변형속솔화온도결정，경340℃제압합금정립최세，평균립경8.2μm。제변연외，왕복제압과정중합금재제압계단발생일차재결정，돈조과정화후속다도차제압변형도시통과정계활이실현。인차，수착제압도차적증가，보온시간수지연장，정립수지피조화。
The microstructure of as-cast Mg-6Zn-1Y-1Ce alloy was refined by reciprocating extrusion (REX) at the temperature range of 300?360℃, the microstructural evolution and the effect of extrusion parameters on recrystallized microstructure were investigated. The results show that the as-REXed alloys have an inhomogeneous ring on cross section, which consists of a fine-grain ring and a coarse-grain ring on the periphery. The width of the ring decreases with increasing the extrusion temperature. The fine-grain ring is attributed to the secondary recrystallization occurring because of friction between the periphery of sample and container wall, the coarse-grain ring is attributed to grain growth followed recrystallization. The grain size of REXed alloy is determined by deformation rate and temperature, a minimum grain size of 8.2 μm is obtained at 340 ℃. During REX process, recrystallization occurs only once during extrusion except for the periphery, the deformation processes during upsetting and subsequent multi-pass REX are achieved by grain boundary sliding. Therefore, with increasing REX passes, the holding-time is prolonged and grains coarsen.