Height Stability Control of CuCrZr Alloy Based on Forming Characteristics and Droplet Transfer Behaviors in Wire Arc Additive Manufacturing

The manufacturing of high-performance Cu alloys by wire arc additive manufacturing (WAAM) presents significant challenges due to the high thermal conductivity. The key issues, such as forming regularity and height stability control, have not been completely solved. In this paper, the effect of current frequency and tungsten electrode distance (TD) on the forming characteristics and deposition process of CuCrZr were investigated. The results revealed that the forming was affected by the behaviors of molten pool and metal droplet. The molten pool was relatively stable at 1 kHz with a minimum height fluctuation. At 50 Hz, with the maximum height instability, a larger molten pool oscillation than at other frequencies resulted from the superposition of oscillations caused by the arc force and the metal droplet. On the other hand, the heat input, arc size increased and molten pool fluctuations were enhanced with the increase of TD, which ultimately affected the forming dimensions. And the droplet transfer behaviors changed from the continuous to discontinuous transition. Based on the above analysis, a height compensation control method was proposed by adjusting the TD according to the deposition height of the previous layer at 1 kHz frequency. The better forming stability indicated the effectiveness of control method.