A Survey of Wire Arc Additive Manufacturing Technologies for Metal Materials

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. © 2023 Editorial Office of Chinese Journal of Rare Metals. All rights reserved.