通过高温热压缩实验研究喷射成形 7055 铝合金的热变形行为,实验温度为 340~480 ℃,应变速率为0.001~1 s-1.结果表明:该合金在变形过程中的流变应力随着温度升高和应变速率的降低而降低,在480 ℃时会出现失稳现象.变形过程中的主要软化机制为动态回复和动态再结晶,其中低温时,动态回复占主导地位,随着温度升高,软化机制逐步转变为动态再结晶,再结晶晶粒的尺寸随着温度的升高而增大.基于动态材料模型和极化互惠模型,结合热变形中的组织演变,确定该合金在应变量为0.7时的适宜加工范围为:温度范围400~420 ℃,应变速率0.01~0.1 s-1,此时对应的动态材料模型加工图能量耗散效率超过33%,极化互惠模型加工图内在加工参数在65%~70%之间.%The hot deformation behavior of spray formed 7055 aluminum alloy was studied by a series of isothermal compression tests at different temperatures ranging from 340 ℃ to 480 ℃ and strain rates varying from 0.001 s-1to 1 s-1. The results show that the flow stress decreases with increasing temperature and deceasing strain rate, and the instable behaviors occurs at 480 ℃. The main softening mechanisms are dynamic recovery and dynamic recrystallization. The dynamic recovery occurs at low temperature and it turns to dynamic recrystallization as temperature increases. The grain size increases with increasing temperature. Based on dynamic materials model, polar reciprocity model and microstructure evolution, the appropriate processing conditions for this alloy are in the strain rate range of 0.01-0.1 s-1 and deformation temperature range of 400-420 ℃, with power efficiency over 33% and intrinsic workability parameter of 65%-70%, respectively.
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