Understanding Defect Formation Mechanisms and Minimization Strategies in EBM Ti-6Al-4V

Due to the layer-by-layer nature of additive manufacturing processes, parts commonly present defects. While considering applications, it is necessary to try and eliminate these defects through, for example, changes to process parameters. However, defects can act as “fossil records”, providing valuable information about how and when they formed in the process, which can aid in the development of strategies for their reduction or minimization. Compositional, crystallographic, microstructural, and morphological aspects of defects and their surroundings have been used to reveal information about the complex physics at play during the additive manufacturing process, including stresses (thermal gradients), keyholing, melt pool fluid flow, and grain growth and nucleation, among others. Defect distribution across scan strategies has been used to reveal information about the formation and retention of gas pores, offering insight into adjustments that might reduce or eliminate gas porosity in future builds. Understanding the mechanisms of formation of defects and their distributions can therefore be used to optimize processes in ways to mitigate or avoid the conditions that promote defect formation.