均匀化处理Al-Mg-Mn合金的组织及热变形行为

研究了半连续水冷铸造方法制备的Al-Mg-Mn合金均匀化处理过程中显微组织的演变过程,同时采用 Gleeble-1500热模拟试验机对均匀化退火态合金的高温塑性变形行为进行了研究,分析了合金流变应力与变形温度和变形量之间的关系,并对合金变形过程中显微组织变化进行了探讨。结果表明,均匀化处理后原铸态合金中粗大的非平衡析出相逐渐溶解,变细、断裂,趋于球化,呈珠链状,数量减少。在热模拟变形过程中,475 ℃×15 h 均匀化退火态Al-Mg-Mn合金流变应力随着变形温度升高而降低;随着变形量增加,流变应力的峰值增大。随着变形温度升高,合金热变形组织首先发生缓慢的回复,位错密度降低,进而形成亚晶、出现再结晶晶粒组织特征。

Microstructure and hot deformation behavior of Al-Mg-Mn alloy after homogenization

Microstructure evolution of Al-Mg-Mn alloy prepared by the direct chill casting was studied during the homogenization process. The plastic deformation behavior of the alloy at high temperature was investigated by using Gleeble-1500 thermal simulation testing machine. The relationship between flow stress and deformation temperature, deformation amount of the alloy was analyzed, and the microstructure change of the alloy during deformation was also discussed. The results show that after homogenization, coarse non-equilibrium precipitates of the as-cast alloy gradually dissolve and decrease in the amount, and become fine, break, tend to spheroidize, appear as bead chains. During the thermal simulating deformation process, the flow stress of the alloy homogenization annealed at 475 ℃ for 15 h decreases with the increase of deformation temperature, and the peak value of the flow stress increases with the increase of deformation amount. As the deformation temperature rises, the hot deformed microstructure firstly recovers slowly, the dislocation density decreases, then forms sub-grains and microstructure with recrystallized grain characteristics.