A6061鋁合金於半熔融狀態之顯微結構研究

Abstract

在半固態成形的過程中，製程的控制與材料的流變性質是影響產品品質的重要關鍵。在材料的流變性質上，主要是受材料於半固態黏漿狀態下的顯微結構所影響，如晶粒的型態愈接近等軸狀，則流動性愈加；晶粒的尺寸愈小，則產品的機械性質愈好。本研究以A6061合金為材料，採用K. P. Young所提出的應變導引熔漿活化法（Strain Induced Melt Activated，SIMA）為半固態黏漿的製造方法，藉由控制施於材料的壓縮應變量、半固態溫度與持溫時間等三個參數，探討材料於不同的參數組合下的顯微結構變化，嘗試找出具有最佳流動性的材料顯微組織之形成條件。在本實驗中，可獲得最佳之流動行為的參數組合為：壓縮率50％，半固態溫度600℃或610℃，與持溫0.2小時的條件。

During semi-solid forming process, the process parameter combination and the rheological behavior of the material are key factors affecting the quality of product. The rheological behavior is mainly affected by the microstructure of material in semi-solid state. For example, the more spherical the grain shape, the better the flow-ability; the smaller the grain size, the better the mechanical properties of the product. This study prepared the semi-solid slurry of A6061 alloy with the Strain Induced Melt Activated (SIMA) process proposed by K. P. Young , applied compression on the work piece, adjusted temperature in semi-solid state and holding time, and explored the microstructure under different parameter combinations to investigate the relation between process parameters and microstructure of A6061 in semi-solid state. It is found that the A6061 in semi-solid can get better flow-ability with the parameter combinations－reduction in height 50%, temperature 600℃ or 610℃ and holding time 0.2hr.