移动横向磁场辅助电弧增材制造技术及凝固组织控制机理

项目名称： 移动横向磁场辅助电弧增材制造技术及凝固组织控制机理

项目编号： No.51505210

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 机械、仪表工业

项目作者： 柏兴旺

作者单位： 南华大学

项目金额： 20万元

中文摘要： 本项目采用移动横向磁场控制GMAW电弧增材制造凝固组织及其缺陷。采用理论分析、三维模拟和实验测试相结合的方法，系统研究外磁场对熔池对流状态及其稳定性、温度梯度、溶质分布、熔池表面形貌和凝固界面形貌的影响，着重分析磁控对流向糊状区的热和溶质输运行为，并基于晶根重熔理论研究由此引发的枝晶破碎及碎片输运，建立凝固组织由柱状晶向等轴晶转变(CET)的准则；以实验结果为依据，阐明磁场模式、熔池流态和凝固组织三者之间的因果联系，揭示磁场控制电弧增材制造凝固组织及其缺陷的机理。本研究不仅可以填补焊接熔池尺度下的磁场控制熔池对流及晶体生长机理研究的空白，丰富材料电磁加工理论，还为提高电弧增材制造零件整体使役性能提供理论依据和技术手段。

中文关键词： 电弧增材制造；移动横向磁场；凝固组织控制；枝晶破碎；熔池对流

英文摘要： This study is aimed to control solidification microstructure and its defects in GMAW arc additive manufacturing (AAM) process by utilizing travelling transversal magnetic fields (TTMF). By means of experiments combined with theoretical analysis and 3D simulation, the effect of magnetic field on the convection state and its stability, temperature gradient, solute distribution, surface shape and the solidification interface morphology in melt pool are systematically investigated, the heat and solute transport behaviors into mushy zone by the magnetically forced convection are emphatically analyzed. The criterion for columnar-to-equiaxed transition(CET) is established by investigating the resulting dendrite fragmentation and its transport based on side-arm-remelting theory. Based on experimental results, the causal connection between magnetic field pattern, melt pool convection and solidification microstructure is demonstrated, the control mechanism of microstructure and its defects by magnetic field is revealed. This study can not only fill the blank of scientific research on magnetically controlled convection and crystal growth on the GMAW melt pool size scale, enrich the theory for electromagnetic processing of materials, but also provide theoretic basis and technological means for enhancing the service performance of components fabricated by AAM technology.

英文关键词： Arc additive manufacturing;Travelling transversal magnetic field;Solidification microstructure control;Dendrite fragmentation;Melt pool convection