Effect of inter layer idle time on thermal behavior for multi-layer single-pass thin-walled parts in GMAW-based additive manufacturing

Components fabricated in gas metal arc welding (GMAW)-based additive manufacturing undergo a special thermal process with many reheating cycles, resulting in the complicated thermal behavior. Many process variables can affect the thermal history in GMAW-based additive manufacturing, especially the interlayer idle time. In this paper, three-dimensional transient models were established to research the effect of interlayer idle time on thermal process in GMAW-based additive manufacturing. Meanwhile, a confirmatory test was conducted to verify the effectiveness of the model. The results indicate that the total maximum temperature gradients of the molten pool at the middle points in the models with the interlayer idle time of 2 min, 5 min, and cooling to room temperature are approximately consistent after the fourth layer, and those in the case with continuous deposition decrease gradually. As the deposition height increases, the maximum temperature gradient in molten pool along the deposition path keeps steady in the model with cooling to room temperature. At the deposition ending moment, with the increasing interlayer idle time, the total temperature gradients at the middle points of the layers decrease in the first eight layers and increase in the ninth and tenth layers, while the circumferential temperature gradients increase progressively.