Investigation of the thermal behavior during the direct writing metal additive manufacturing

In metal additive manufacturing, thermal behavior significantly influences the quality of formed parts. Direct writing metal additive manufacturing (DWMAM) technology distinguishes itself from other metal additive manufacturing technologies, which use laser or electron beam as the heat source, due to its extremely low heat input and slow heating and cooling rate. This greatly reduce the difficulty of regulating the thermal behavior during the additive manufacturing processes. This article focuses on a systematic investigation into the thermal behavior of the DWMAM process, employing theoretical analysis, simulations, and experimental research. A transient heat transfer model was established to characterize the formation of the first layer, followed by comprehensive simulations and experimental investigations of both the first-layer formation and the subsequent deposition of multiple layers. The temperature variation predicted by the mathematical model is consistent with the simulation and experimental results. The results showed that the maximum heating and cooling rates in DWMAM processes are hundreds of K/s. Additionally, slower writing speeds and higher heating powers result in increased thermal input. An appropriate thermal input can achieve favorable interlayer metallurgical bonding and high-quality formed parts. The research conducted in this study on the thermal behavior of the writing process will provide theoretical and experimental guidance for DWMAM and lay a solid foundation for the further advancement of this technology.