Discontinuities in the laser powder bed fusion alloys: A review
Mahdi Yeganeh, Zahra Shahryari, Mohammadreza Tavakoli Shoushtari, M. Eskandari
Abstract
There are several significant microstructural discontinuities in alloys produced by laser powder bed fusion (LPBF). This review focuses on the primary discontinuities arising in the LPBF manufactured alloys, including gas pores, lack of fusion (LOF), keyholes, cracks, and melt pools. It also examines the causes of these discontinuities, the effects of various factors, and techniques to reduce them. The structural integrity of LPBF-generated components is affected by these discontinuities. This review also mentions strategies to reduce or eliminate these defects to increase the reliability of the LPBF process. It shows that some defects can be minimized by choosing correct parameters, such as laser power and scan speed. However, some specific defects cannot be diminished by selecting parameters and require other options, such as post-treatments (e.g., heat treatment or hot isostatic pressing). Additionally, post-treatments and alloy composition modifications can help to adapt the material's characteristics and lower the discontinuity percentage.