Control of wire melting behavior during laser hot wire deposition of aluminum alloy

Laser wire deposition (LWD) is a promising method with a great potential for the fabrication of large open-frame components. Using hot wire in such a process, referred to as laser hot wire deposition (LHWD) would improve the laser absorption and deposition rate. In this work, the LHWD process of aluminum-alloy wire was studied with particular attention to the wire transfer behaviors. The results show that the wire melting rate could still be effectively increased even for the low-resistivity aluminum wire. The preheating current has a great influence on the wire transfer dynamics. Analysis demonstrates that the key to maintaining stable wire melting and transfer is to control the wire tip temperature by matching the wire feed speed and preheating current under certain laser power. A model computing the dynamic preheating process was established to predict the wire tip temperature with or without resistance preheating. A criterion based on the predictions was proposed to determine the optimal match of wire feed speed and wire preheating current, and thereby provided a deeper understanding of LHWD process.