How X-rays reveal the behavior of spatter in 3D printing

The investigations carried out by the UCL researchers show and explain the relationships between the form of vapor depression and the spatter dynamics during LPBF under various industry-relevant processing conditions.

Spatter, i.e. sprayed particles that form during the melting process, are a significant factor for surface defects in additively manufactured components. These defects can impair the fatigue strength of the components, which is particularly important in safety-critical applications.

“Spatter is one of the main concerns in industrial 3D printing applications that can contribute to porosity formation and rough surface,” said Chu Lun Alex Leung, the corresponding author on the paper and Associate Professor of UCL Mechanical Engineering. “Adoption of LPBF for safety critical applications is hindered by the challenge of achieving defect-lean, high surface quality metallic components.”

The team used a specially developed 3D printing system, the so-called Quad-ISOPR (Quad-laser in situ and operando process replicator), for their experiments. This system comprises four lasers and an industrial scanning system that works in a chamber with argon gas. This enabled the researchers to observe the dynamics of the melt pool and spatter in real time using high-resolution synchrotron X-rays.

Professor Peter D. Lee, also a corresponding author and Professor of UCL Mechanical Engineering, emphasized, “Currently, research on spatter during LPBF is limited, and our goal is to improve our understanding of spatter formation mechanisms using high-energy synchrotron X-ray sources.”

“Our work predicts the number of spatters formed during LPBF of an Al-Zr-Fe alloy system,” said first-author Da Guo, post-doc in the school. “This prediction can be used for future model validation and minimizing spatter.”

The researchers plan to extend their work to other commercial materials to achieve higher surface quality in additively manufactured components. The aim is to promote the widespread use of LPBF in industry, particularly in areas where component integrity is critical.