金属材料电弧增材制造技术研究现状

A Survey of Wire Arc Additive Manufacturing Technologies for Metal Materials

电弧增材制造(WAAM)技术将电弧作为热源,具备熔敷效率高、设备简单、成本较低的特点,在制备大型零件时具有更大的优势。基于3种典型电弧热源的电弧增材制造方法包括熔化极电弧(GMA)增材制造、非熔化极电弧(GTA)增材制造与等离子弧(PA)增材制造。GMA增材制造技术拥有熔敷效率高、易于实现等特点,特别是基于冷金属过渡(CMT)的增材制造技术取得了重要进展,主要缺点在于熔滴过渡对熔池的显著冲击易影响成形精度和质量。GTA增材制造技术具有最为稳定的电弧燃烧过程,具有无飞溅、成形精度与质量高等显著优势,特别适合于铝合金、镍基合金、钛合金等材料的增材制造。PA增材制造与GMA增材制造与GTA增材制造相比,存在能量密度高、集束性好等优点。但是PA合理参数区间较窄、参数匹配复杂、热输入大等缺点也限制了其在该领域的应用。由于增材制造过程使得后堆积层存在反复加热与冷却,增材制造成形件组织存在上中下区域的差异以及熔敷方向及垂直于熔敷方向性能的各向异性。增材制造金属材料的热循环过程对于晶粒尺寸、熔覆层性能以及成形精度非常关键,分别可以通过改变成形件冷却条件、改变熔池凝固条件对组织性能进行改善。新型电弧热源的不断涌现,为显著提高电弧增材制造成形精度与组织性能提供了更多选择。

Wire arc additive manufacturing(WAAM)technology employs arc as heat sources,which own the characteristics of high deposition efficiency,simple equipment and low cost,and has great advantages especially for large parts production.In terms of arc heat source modulation,many researchers put forward arc additive manufacturing technology with different modification and modification of traditional arc.WAAM can be classified into three typical methods according to different arc heat sources,i.e.gas metal arc(GMA)additive manufacturing,gas tungsten arc(GTA)additive manufacturing and plasma arc(PA)additive manufacturing.GMA additive manufacturing technology has the characteristics of high deposition efficiency and easy to implement,especially the additive manufacturing technology based on CMT cold metal transfer has made important progress;the main disadvantage is that the droplet transfer might impact on the molten pool and affect the forming accuracy and quality.GTA additive manufacturing technology has the most stable arc burning processes,no spatter,high forming accuracy and high quality,especially suitable for aluminum alloy,nickel base alloy,titanium alloy and other metal materials.Compared with GMA and GTA,PA has the advantages of higher energy density,constriction and good directivity.However,the shortcomings of plasma arc,such as narrow reasonable parameter ranges,complex parameter matching and high heat input,also limit its application in this field.Due to the repeated heating and cooling of the layers during additive manufacturing,there are differences in the upper,middle and lower regions of the microstructure and anisotropy,and the properties are much different both along and perpendicular to the cladding direction.The thermal cycling process of additive manufacturing of metal materials is very important for grain size,layer performance and forming accuracy.Reducing the heat input in the manufacturing process of arc additive is of great significance for grain refinement,performance improvement and forming accuracy.Domestic and foreign scholars have carried out many studies on the control of heat input and grain refinement in the additive process.Additional assistance is an effective method,including cooling gas shock,ultrasonic vibration,adding nucleating agent and so on.According to the different ways to improve the microstructure,they are divided into two categories,namely,changing the cooling conditions of forming parts and changing the solidification conditions of molten pool.The emergence of new arc heat sources provides more choices for improving the forming accuracy and microstructure performance of arc additive manufacturing.With the application prospect of additive manufacturing technology becoming more and more extensive,the industrial field has higher and higher requirements for production efficiency,production cost and quality of molded parts,and arc additive manufacturing technology that uses arc as a heat source shows significant advantages of high efficiency,low cost and high quality.Arc additive manufacturing technology based on melting electrode has outstanding production efficiency advantages,can obtain high deposition efficiency,the accompanying droplet transition behavior caused by momentum impact,droplet overheating,easy to produce splash,etc.are the main problems of this type of technology,cold metal transition(CMT)technology reflects obvious advantages.Compared with melted polar arc additive manufacturing,arc additive manufacturing technology(GTA,PA)based on non-melting pole has lower deposition efficiency,but has a more stable arc combustion,molten pool solidification and forming process,and the efficiency of additive manufacturing technology compared with laser and electron beam heat source is greatly improved,which has excellent comprehensive technical advantages.Based on visualization,electrical signal,etc.,it is one of the current research hotspots to realize the fine control of the arc additive manufacturing process,obtain a more stable forming process and improve the quality of the formed parts.The study of new types of modified and modified arcs,flexible regulation of heat input,and regulation of the microstructure properties of formed parts had important theoretical significance and engineering practical value for improving the quality and widening application of arc additive manufacturing components.