Metal lightweight features processed by powder bed fusion additive manufacturing: Process, microstructure and dimensional dependency

Abstract

Additive manufacturing (AM) has been widely regarded as the most suitable manufacturing technology of many advanced design concepts that typically generate geometrically-complicated designs, such as topology optimization structures and cellular metamaterials. Many of the targeting applications for these design concepts involve lightweight and performance-efficient metal structural components, which have been demonstrated extensively using the powder bed fusion AM (PBF-AM) processes. However, currently there exist very limited real-world applications with the lightweight structures for critical components, despite the abundance of both the design tools and theoretical frameworks. A major barrier exists within the processing space. With the characteristic features such as thin walls and thin struts approaching the process resolution limit, these lightweight designs are increasingly susceptible to the dynamic and unstable process effects. Various factors such as process instability and stochasticity, transient process physics and process parameter setting can significantly influence the various material characteristics of the lightweight features, which in turn exhibit unique geometry-process-material (GPM) relationships that are different from the established knowledge based on the bulk geometries. Notably, the material properties of PBF-AM lightweight features also exhibit geometry dependency, which makes many design methods ineffective of even in feasible. This work provides a review of the existing state of the art with the understanding of the processing aspects of the metal PBF-AM lightweight features, in the attempt to elucidate critical knowledge gaps and to inform potential research directions.