Effect of build interruption during laser powder bed fusion process on structural integrity of Ti-6Al-4V

The growing concern for global sustainability highlights the need to address waste generation in metal additive manufacturing (AM) processes. Even with proper planning, unexpected incidents such as software glitches and power outages may interrupt AM processes by pausing the build sequence, leading to a waste of resources (i.e. time, money, and materials). The layer-wise nature of AM processes allows for interrupted builds to be resumed from the stopping point. Nevertheless, interrupting the build process (i.e. pausing and resuming) can compromise the structural integrity of the fabricated parts, potentially leading to localized failure near the interruption location. The objective of this study is to investigate the effect of build interruption during the laser beam powder bed fusion process on the structural integrity of Ti-6Al-4V specimens. Tensile and fatigue tests were performed to assess any possible contribution of build interruption to the specimen failures under monotonic and cyclic loading, and the results were compared with their control counterparts, fabricated without interruption. Tensile and fatigue failures as well as the propagation of a secondary crack were observed at the interruption location. Our experimental observations indicate that when large process-induced defects are present, build interruption plays a peripheral role in the fatigue life and failure mechanism of specimens, with defects being the overriding factor. None of the heat-treated specimens exhibited any tensile or fatigue failures at the interruption location, suggesting that an appropriate heat treatment can be effective in reducing the risk of localized failure near the interrupted location.