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为了研究7055铝合金在热压缩过程中的组织演变规律,基于元胞自动机法(CA)建立7055铝合金动态再结晶(DRX)模型。为了获得模型的材料参数,进行单道次热压缩实验,通过最小二乘法拟合获得7055铝合金的位错密度模型、形核率模型和再结晶晶粒长大模型。研究应变、应变速率、变形温度和初始晶粒尺寸对热压缩过程中显微组织演变的影响。结果表明:在热压缩过程中,动态再结晶使材料晶粒明显细化。大应变、高温和低应变速率有利于晶粒细化;动态再结晶晶粒的稳态晶粒尺寸与初始晶粒大小无关,而取决于温度和应变速率的变化;分析热压缩过程动态再结晶动力学规律。由CA仿真流变应力值和仿真组织图与实验结果的对比可知,所建立的基于CA法的动态再结晶模型能有效地预测7055铝合金在热变形过程中的动态再结晶组织演变规律。
In order to study the microstructure evolution of 7055 aluminum alloy during hot compression, a 7055 aluminum alloy dynamic recrystallization (DRX) model was established based on the cellular automata method (CA). In order to obtain the material parameters of the model, a one-pass thermal compression test was carried out and the dislocation density model, the nucleation rate model and the recrystallized grain growth model of the 7055 aluminum alloy were obtained by least square fitting. The effects of strain, strain rate, deformation temperature and initial grain size on the microstructure evolution during hot compression were investigated. The results show that during the process of hot compression, the dynamic recrystallization can refine the grain of the material remarkably. Large strain, high temperature and low strain rate are conducive to grain refinement; dynamic recrystallization grain steady-state grain size and the initial grain size has nothing to do, but depends on the temperature and strain rate changes; analysis of hot compression process of dynamic recrystallization Dynamic laws. Comparing the flow stress value of CA simulation and the simulation histogram with the experimental results, we can know that the dynamic recrystallization model based on CA method can effectively predict the dynamic recrystallization microstructure evolution of 7055 aluminum alloy during thermal deformation.