Nowadays, additive manufacturing (AM) using laser powder bed fusion (LPBF) is acknowledged for its ability to generate near-net-shape components for various industries such as aerospace, automotive, and health industries. However, internal defects seem to be the inevitable concomitant in the current state of laser powder bed fusion of Al alloys. Hence, knowledge of the formation, different types, and morphologies of pores and their suppression is an essential element for successful future AM applications. The purpose of this research is to qualify a new approach of defect classification using X-ray tomography. In this framework, this research examined the influence of size, shape, and location of pores on crack initiation for AlSi10Mg parts produced by LPBF. For this reason, a total number of 39,228 pores detected in a cylindrical sample were categorised. Additionally, 26 selected pores of different morphology from the X-ray scan were analysed by means of finite element analysis (FEA). Moreover, fracture mechanics determinations were carried out to examine the correlations between pore characteristics and degree of stress concentration. The result is an evaluated novel pore classification method that can be used for process adjustments, quality assurance, as well as further research.
Due to high production costs and a limited reproducibility of quality, the high potential of laser powder bed fusion (LPBF) has not been fully exploited yet. In fact, internal defects can have a detrimental effect on the fatigue behaviour and cause final component failure. Therefore, process-induced defects must be localized and evaluated at a higher level of detail. The present study deals with the correlation amongst pores and LPBF process parameters in AlSi10Mg components. Computed tomography (CT) allows an extensive examination of internal defects. Within this work, a total number of 2,939,830 pores detected in 96 cylindrical samples were analysed using CT. The formation of pores can be adjusted by varying the modified volume energy density, for example, by using various laser scanning speeds. Furthermore, the effect of powder preparation scan strategies (pre-heating and pre-sintering) on the formation of different pore types as well as the general reproducibility was examined. For instance, the shielding gas flow, contaminated protective windows of the lasers as well as prior powder preparation influence the formation of pores. Using prior laser powder preparation reduced the total number of pores at high scanning speeds up to 45%. When the scanning speed is increased, the number of spherical pores decreases and large and irregularly shaped pores appear. Interestingly, only the pre-heating process resulted in a reduced formation of spherical pores at low scanning speeds (1000 mm/s).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.