Al-4Cu-Mg合金的半固态成形研究

【作者】 卢雅琳；

【导师】 李淼泉；

【作者基本信息】 西北工业大学 ， 材料加工工程， 2004， 硕士

【摘要】 由于材料在半固态下具有特殊性质，开展其变形行为、变形机理和组织演化等方面的研究显得尤为重要。建立符合实际变形过程的流变应力模型，并将其耦合到有限元数值模拟中，研究材料在半固态成形过程中的温度场、应力场和应变场的分布规律，预测金属在成形过程中的充型行为、可能产生的缺陷和最佳工艺参数等信息，为实际生产提供理论依据。 本文完成了Al-4Cu-Mg合金的热模拟压缩实验，研究了变形温度、应变和应变速率对变形行为的影响。以Al-4Cu-Mg合金变形行为分析为基础，综合考虑各变形参数对流变应力的影响，建立了描述半固态材料流变行为的流变应力模型。该模型形式简单，能够较好地描述半固态合金的变形行为。 将本文建立的流变应力模型耦合到有限元中，对半固态Al-4Cu-Mg合金的反挤压过程进行了变形-传热耦合数值模拟。研究了变形工艺参数，包括变形温度、凸模速度、凸模压下量、挤压比和摩擦因子，对变形过程中应力、应变和温升的影响。 本文完成了半固态Al-4Cu-Mg合金的反挤压成形。实验结果与数值模拟结果的对比结果表明，在变形开始和进入稳态阶段，数值模拟结果与实验结果比较吻合。在载荷快速上升阶段，数值模拟结果与实验误差较大。主要原因是在Al-4Cu-Mg合金的半固态成形过程中，微观组织演化对变形行为有较大影响。更多还原

【Abstract】 It is important to study deformation behavior, deformation mechanism and microstructure evolution of semi-solid alloys because the semi-solid alloy has special characterization. To establish the constitutive relationship consistent with practice and couple with plastic deformation and heat transfer will be beneficial to realize the distribution of stress, strain and temperature raise during the deformation processes. To predict whether defects occur or not and optimize the process parameters could provide scientific foundation of metal forming.In this paper, deformation behavior of the semi-solid Al-4Cu-Mg alloy has been investigated by isothermal compression. Effect of the process parameters, including deformation temperature, strain and strain rate, on deformation behavior has been deeply discussed. Based on the deformation behavior of semi-solid Al-4Cu-Mg alloy, a constitutive relationship of semi-solid alloy has been established. It has been proved to be a simple model, which can represent the deformation behavior of semi-solid alloys.Writing the constitutive relationship to FE code, a coupled simulation of plastic deformation with heat transfer has been carried out in the backward extrusion of semi-solid Al-4Cu-Mg alloy. Effect of the process parameters, including deformation temperature, punch velocity, height reduction, extrusion ratio and shear factor of friction on the equivalent stress, the equivalent strain and the temperature raise during the semi-solid backward extrusion has been studied.Finally, backward extrusion of semi-solid Al-4Cu-Mg alloy has been carried out. The experimental result is in agreement with the calculated result in the initial stage and final stage. Meanwhile, microstructure evolution might affect the deformation behavior in the semi-solid state and should be studied deeply.更多还原