铝合金多源超声波铸造凝固行为的数值模拟与工艺研究

项目名称： 铝合金多源超声波铸造凝固行为的数值模拟与工艺研究

项目编号： No.51475480

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 机械、仪表工业

项目作者： 李晓谦

作者单位： 中南大学

项目金额： 80万元

中文摘要： 对金属凝固过程施加超声波扰动是提高铸造成形性和组织均匀性、抑制气孔、疏松、偏析与开裂等缺陷的一个重要途径。对于突破航空航天和武器装备所需的高强高韧铝合金大型复杂整体构件的铸造技术瓶颈具有重要意义。施加多源超声协同扰动与参数调控是大型铸件超声铸造工艺实现的关键难题。针对于此，本项目将开展大型铝合金铸锭多源超声波铸造数值模拟与工业化中试规模的工艺实验研究，探明多源超声场协同作用下铝合金的凝固行为，构建包含多源声场、流场、温度场、应力场的多场耦合模型。通过数值模拟，获得铸锭凝固过程中的声场、流场与温度场的宏观分布特征，揭示多源超声场对铝合金凝固过程的作用机理与不同物理能场间的能量传递规律，并在微观尺度内建立晶体生长的外场条件如多源超声的布控位置、方式、超声频率、振幅等参数与铸锭组织对应关系的理论体系，并开展工艺实验验证与完善数值模型，为超声波铸造技术的工业化运用提供理论依据与技术支持。

中文关键词： 铝合金；超声铸造；多场耦合；凝固行为；数值模拟

英文摘要： Exerting ultrasonic perturbation in the process of metal solidification is an important way that not only can enhance the casting formability and homogeneity of structure, but also inhibit some cast defects, such as porosity, shrinkage cavities and segregation in ingots. So this technology is significant for the breakthrough of casting technology bottleneck in the development of high-strength, high-toughness, large-size and complex integral aluminum component for the equipments of aviation and weapon. Synergistic perturbation of multi-source ultrasound and adjustment of parameters are a key challenge to accomplish ultrasonic casting process for the large-size ingots. Aim to above problems, numerical simulation of multi-source ultrasound casting is carried out in this project as well as the technological test is studied at an industrialized pilot scale. Solidification behavior of aluminum alloy is verified under the synergistic action of multi-source ultrasonic fields. A multi-field coupling model that include multi-source sound field, flow field, temperature field and stress field is built. Macroscopic distribution characteristics are obtained by numerical simulation on sound, flow and temperature fields in the process of ingot solidification. Through the study, it could reveal the mechanism of action of multi-source ultrasonic fields on solidification of aluminum alloy and clarify the rule of energy transfer between various physical fields. The theory system within the micro scale is established, which based on the corresponding relation between micro-structure of ingot casting and external field conditions of crystal growth, such as the introducing position and pattern of multi-source ultrasound, vibration frequency and amplitude, etc. At last, results of numerical simulation is validated, amended and completed by industrial experiments. All of these would provide theoretical foundation and technical support for speeding up the industrial application of ultrasonic casting technology.

英文关键词： aluminum alloy;ultrasonic casting;multi-field coupling;solidification behavior;numerical simulation