镁合金CMT摆动电弧熔敷增材+FSP复合制造成形机理研究

镁合金材料作为最轻金属结构材料，在汽车、航天、电子、轨道交通等领域的需求及应用日益增大。电弧增材制造使得制备高性能复杂结构镁合金零件成为可能。针对镁合金的电弧增材制造，提出了一种冷金属过渡（CMT）摆动电弧熔敷增材与搅拌摩擦处理（FSP）复合制造成形的方法。拟采用CMT技术进行镁合金的电弧熔敷增材，通过加入电弧摆动，以改善成形情况并细化熔敷成形层组织；重点研究CMT参数以及电弧摆动模式与参数对镁合金熔敷过程电弧形态、熔滴过渡行为及宏观成形的影响规律，阐明镁合金CMT摆动电弧熔敷成形机理。通过引入FSP以改善熔敷成形层的微观组织和性能，重点研究熔敷成形层非平整条件下的FSP对熔覆成形层微观组织及性能的影响规律及微观组织演化机理，以及FSP对气孔、裂纹等缺陷的消除机理。提出镁合金CMT+FSP复合制造成形与性能的控制方法与策略，实现镁合金构件的高质量增材制造。

Magnesium alloy, as the lightest structural metallic materials, has been widely applied in the automotive, aerospace, electronics, and transportation, and its demand in these fields has increased remarkably. The development of wire and arc additive manufacturing (WAAM) technique allows for the production of high-performance magnesium alloy parts with complex structures. Aiming at the WAAM of magnesium alloy, a hybrid forming method of cold metal transfer (CMT) weaving arc deposition and friction stir processing (FSP) is proposed. Arc weaving is introduced during magnesium alloy deposition by CMT technique to improve the forming and refine the grains of deposited layer. The focus of this part is to clarify the effects of CMT parameters, and weaving pattern and parameters on the arc characteristics and metal transfer behavior during deposition process and appearance of the desposited layer. Then，the forming mechanism of CMT weaving arc deposition will be revealed. To improve the microstructure and performance of the deposited layer, FSP is introduced after deposition process. The effect of FSP on the microstructure and performance of the deposited layer will be studied. And the microstructural evolution of the deposited layer and elimination mechanism of defects (such as pores and cracks) in the deposited layer will be clarified. Control strategies and methods for forming and properties of magnesium alloy by arc weaving CMT + FSP hybrid manufacturing will be proposed to realize high-quality additive manufacturing of magnesium alloy.