Thermal Behavior in Wire Arc Additive Manufacturing: A Comparative Study of the Conventional Process and Infrared Heater Use

Wire arc additive manufacturing (WAAM) is a directed energy metal additive manufacturing technology that features high-speed production of large and dense parts. The process is exposed to thermal shocks due to a high heat input. These thermal shocks may lead to various issues, including distortions, residual stresses, surface morphology defects, and irregular macro- and microstructures. This study proposes adopting infrared heaters in the WAAM process. Thus, it presents a preliminary investigation to promote further studies of the effects of infrared heating on the WAAM process and the quality of the produced parts. An experimental study was carried out to observe the effects of infrared heaters on part quality in WAAM. Two walls were built using ER70S-6 welding wire to compare the conventional WAAM process with the WAAM process that used an infrared heater. The results showed that the wall produced by WAAM with infrared heaters had more regular geometries, refined internal structures, and stable mechanical properties. The optic and SEM images showed that this method reduced the acicular and polygonal ferrite structures. Notably, bainite formation was not observed, and there was a decrease in the formation of defects, such as pores, lack of fusion, and interlayer discontinuities. The specimen subjected to the external infrared heater exhibited approximately 17% higher tensile strength than the standard WAAM specimen. Moreover, the WAAM with infrared heater procedure reduced the microhardness variations along the build direction by 12% compared to the 30% reduction achieved by the conventional WAAM process.