In recent years, scholars have proposed a metal wire forming method based on the Joule heat principle in order to improve the accuracy of additive manufacturing and reduce energy consumption and cost, but it is still in the theoretical stage. In this paper, a mathematical model of resistance additive manufacturing was established using finite element software, and the temperature variation of the melting process under different currents was analyzed. A suitable current range was preliminarily selected, and an experimental system was built. Through experimental study of the current and wire feeding speed, the influences of different process parameters on the forming appearance of the coating were analyzed. The results showed that the forming appearance was the best for Ti-6Al-4V titanium alloy wire with a diameter of 0.8 mm, when the current was 160 A, the voltage was 10 V, the wire feeding speed was 2.4 m/min, the workbench moving speed was 5 mm/s, and the gas flow rate was 0.7 m³/h. Finally, the process parameters were used for continuous single-channel multilayer printing, verified the feasibility of the process at the experimental level and provided reference data for the subsequent development of this technology.

In this study, a solution to the issue of a large heat-affected zone in Wire Arc Additive Manufacturing is presented by employing the Joule Heat Additive Manufacturing method to create a single layer and single channel with a reduced heat-affected zone. The microstructure of the single layer and single channel is thoroughly investigated using various detection methods, including optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD). The results reveal that the heat-affected zone formed by the Joule Heat Additive Manufacturing method is smaller than that produced by the Wire Arc Additive Manufacturing method. Additionally, the grains in the single layer and single channel progress from planar to columnar, then equiaxed, and finally back to columnar from the fusion line to the top of the wire. The element content and distribution are relatively uniform. The microstructure of the single layer consists of austenite and a small amount of ferrite, with austenite accounting for 99.71% of the content. The grain size in the middle of the wire is mainly around 10 μm, with the smallest angle grain boundaries within 10°. The distribution of local grain orientation differences in the three regions is found to be largely consistent. The analysis of the microstructure of the single layer and single channel serves as a valuable reference for understanding the behavior of single-channel multi-layers in future studies.