Study on the role of deposition path in electron beam freeform fabrication process

Purpose - The present work aims to reveal the effect of deposition paths on transient temperature, transient stress, residual stress and residual warping in the electron beam freeform fabrication (EBF) process. Design/methodology/approach - Six typical deposition paths were involved in the finite element (FE) simulations of EBF process by implementing a specially written program. Findings - The results showed that the deposition path had a remarkable influence on heat transfer and transient temperature distribution in the scanning process, resulting in different residual stress and residual warping after cooling to room temperature. The largest and smallest temperature gradients were obtained from the zigzag and alternate-line paths, respectively. Meanwhile, the temperature gradient decreased with the increase of deposited layers. The optimum deposition path, namely, the alternate-line pattern, was determined with respect to the residual stress and residual warping. Originality/value - Although some researcher revealed the importance of deposition path through FE analysis and experimental observation, their studies were usually confined within one type of deposition pattern. A complete investigation of typical deposition paths and comparison among them are still lacking in literature. To address the aforementioned gap, the present work started by extensive FE simulations of EBF process involving six representative deposition paths, namely, the alternate-line, zigzag, raster, inside-out spiral, outside-in spiral and Hilbert. For each deposition path, the transient temperature field, residual stress and residual deformation were obtained to optimize the deposition path.